From b22da3d8526a935aa31e086e63f60ff3246cb61c Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Sat, 09 Dec 2023 07:24:11 +0000
Subject: [PATCH] add stmac read mac form eeprom
---
kernel/kernel/printk/printk.c | 3111 +++++++++++++++++++++++++++++++----------------------------
1 files changed, 1,625 insertions(+), 1,486 deletions(-)
diff --git a/kernel/kernel/printk/printk.c b/kernel/kernel/printk/printk.c
index a1f5484..13cf2d7 100644
--- a/kernel/kernel/printk/printk.c
+++ b/kernel/kernel/printk/printk.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
/*
* linux/kernel/printk.c
*
@@ -16,6 +17,8 @@
* 01Mar01 Andrew Morton
*/
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/tty.h>
@@ -29,11 +32,9 @@
#include <linux/delay.h>
#include <linux/smp.h>
#include <linux/security.h>
-#include <linux/bootmem.h>
#include <linux/memblock.h>
#include <linux/syscalls.h>
#include <linux/crash_core.h>
-#include <linux/kdb.h>
#include <linux/ratelimit.h>
#include <linux/kmsg_dump.h>
#include <linux/syslog.h>
@@ -43,6 +44,9 @@
#include <linux/irq_work.h>
#include <linux/ctype.h>
#include <linux/uio.h>
+#include <linux/kthread.h>
+#include <linux/kdb.h>
+#include <linux/clocksource.h>
#include <linux/sched/clock.h>
#include <linux/sched/debug.h>
#include <linux/sched/task_stack.h>
@@ -53,28 +57,13 @@
#include <trace/events/initcall.h>
#define CREATE_TRACE_POINTS
#include <trace/events/printk.h>
+#undef CREATE_TRACE_POINTS
+#include <trace/hooks/printk.h>
+#include <trace/hooks/logbuf.h>
+#include "printk_ringbuffer.h"
#include "console_cmdline.h"
#include "braille.h"
-#include "internal.h"
-
-#ifdef CONFIG_PRINTK_TIME_FROM_ARM_ARCH_TIMER
-#include <clocksource/arm_arch_timer.h>
-static u64 get_local_clock(void)
-{
- u64 ns;
-
- ns = arch_timer_read_counter() * 1000;
- do_div(ns, 24);
-
- return ns;
-}
-#else
-static inline u64 get_local_clock(void)
-{
- return local_clock();
-}
-#endif
int console_printk[4] = {
CONSOLE_LOGLEVEL_DEFAULT, /* console_loglevel */
@@ -82,6 +71,7 @@
CONSOLE_LOGLEVEL_MIN, /* minimum_console_loglevel */
CONSOLE_LOGLEVEL_DEFAULT, /* default_console_loglevel */
};
+EXPORT_SYMBOL_GPL(console_printk);
atomic_t ignore_console_lock_warning __read_mostly = ATOMIC_INIT(0);
EXPORT_SYMBOL(ignore_console_lock_warning);
@@ -101,6 +91,12 @@
static DEFINE_SEMAPHORE(console_sem);
struct console *console_drivers;
EXPORT_SYMBOL_GPL(console_drivers);
+
+/*
+ * System may need to suppress printk message under certain
+ * circumstances, like after kernel panic happens.
+ */
+int __read_mostly suppress_printk;
#ifdef CONFIG_LOCKDEP
static struct lockdep_map console_lock_dep_map = {
@@ -127,26 +123,38 @@
static int __control_devkmsg(char *str)
{
+ size_t len;
+
if (!str)
return -EINVAL;
- if (!strncmp(str, "on", 2)) {
+ len = str_has_prefix(str, "on");
+ if (len) {
devkmsg_log = DEVKMSG_LOG_MASK_ON;
- return 2;
- } else if (!strncmp(str, "off", 3)) {
- devkmsg_log = DEVKMSG_LOG_MASK_OFF;
- return 3;
- } else if (!strncmp(str, "ratelimit", 9)) {
- devkmsg_log = DEVKMSG_LOG_MASK_DEFAULT;
- return 9;
+ return len;
}
+
+ len = str_has_prefix(str, "off");
+ if (len) {
+ devkmsg_log = DEVKMSG_LOG_MASK_OFF;
+ return len;
+ }
+
+ len = str_has_prefix(str, "ratelimit");
+ if (len) {
+ devkmsg_log = DEVKMSG_LOG_MASK_DEFAULT;
+ return len;
+ }
+
return -EINVAL;
}
static int __init control_devkmsg(char *str)
{
- if (__control_devkmsg(str) < 0)
+ if (__control_devkmsg(str) < 0) {
+ pr_warn("printk.devkmsg: bad option string '%s'\n", str);
return 1;
+ }
/*
* Set sysctl string accordingly:
@@ -165,14 +173,14 @@
*/
devkmsg_log |= DEVKMSG_LOG_MASK_LOCK;
- return 0;
+ return 1;
}
__setup("printk.devkmsg=", control_devkmsg);
char devkmsg_log_str[DEVKMSG_STR_MAX_SIZE] = "ratelimit";
int devkmsg_sysctl_set_loglvl(struct ctl_table *table, int write,
- void __user *buffer, size_t *lenp, loff_t *ppos)
+ void *buffer, size_t *lenp, loff_t *ppos)
{
char old_str[DEVKMSG_STR_MAX_SIZE];
unsigned int old;
@@ -210,16 +218,7 @@
return 0;
}
-/*
- * Number of registered extended console drivers.
- *
- * If extended consoles are present, in-kernel cont reassembly is disabled
- * and each fragment is stored as a separate log entry with proper
- * continuation flag so that every emitted message has full metadata. This
- * doesn't change the result for regular consoles or /proc/kmsg. For
- * /dev/kmsg, as long as the reader concatenates messages according to
- * consecutive continuation flags, the end result should be the same too.
- */
+/* Number of registered extended console drivers. */
static int nr_ext_console_drivers;
/*
@@ -233,19 +232,7 @@
static int __down_trylock_console_sem(unsigned long ip)
{
- int lock_failed;
- unsigned long flags;
-
- /*
- * Here and in __up_console_sem() we need to be in safe mode,
- * because spindump/WARN/etc from under console ->lock will
- * deadlock in printk()->down_trylock_console_sem() otherwise.
- */
- printk_safe_enter_irqsave(flags);
- lock_failed = down_trylock(&console_sem);
- printk_safe_exit_irqrestore(flags);
-
- if (lock_failed)
+ if (down_trylock(&console_sem))
return 1;
mutex_acquire(&console_lock_dep_map, 0, 1, ip);
return 0;
@@ -254,13 +241,9 @@
static void __up_console_sem(unsigned long ip)
{
- unsigned long flags;
+ mutex_release(&console_lock_dep_map, ip);
- mutex_release(&console_lock_dep_map, 1, ip);
-
- printk_safe_enter_irqsave(flags);
up(&console_sem);
- printk_safe_exit_irqrestore(flags);
}
#define up_console_sem() __up_console_sem(_RET_IP_)
@@ -275,11 +258,6 @@
static int console_locked, console_suspended;
/*
- * If exclusive_console is non-NULL then only this console is to be printed to.
- */
-static struct console *exclusive_console;
-
-/*
* Array of consoles built from command line options (console=)
*/
@@ -288,6 +266,7 @@
static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES];
static int preferred_console = -1;
+static bool has_preferred_console;
int console_set_on_cmdline;
EXPORT_SYMBOL(console_set_on_cmdline);
@@ -302,30 +281,22 @@
static int console_msg_format = MSG_FORMAT_DEFAULT;
/*
- * The printk log buffer consists of a chain of concatenated variable
- * length records. Every record starts with a record header, containing
- * the overall length of the record.
+ * The printk log buffer consists of a sequenced collection of records, each
+ * containing variable length message text. Every record also contains its
+ * own meta-data (@info).
*
- * The heads to the first and last entry in the buffer, as well as the
- * sequence numbers of these entries are maintained when messages are
- * stored.
+ * Every record meta-data carries the timestamp in microseconds, as well as
+ * the standard userspace syslog level and syslog facility. The usual kernel
+ * messages use LOG_KERN; userspace-injected messages always carry a matching
+ * syslog facility, by default LOG_USER. The origin of every message can be
+ * reliably determined that way.
*
- * If the heads indicate available messages, the length in the header
- * tells the start next message. A length == 0 for the next message
- * indicates a wrap-around to the beginning of the buffer.
+ * The human readable log message of a record is available in @text, the
+ * length of the message text in @text_len. The stored message is not
+ * terminated.
*
- * Every record carries the monotonic timestamp in microseconds, as well as
- * the standard userspace syslog level and syslog facility. The usual
- * kernel messages use LOG_KERN; userspace-injected messages always carry
- * a matching syslog facility, by default LOG_USER. The origin of every
- * message can be reliably determined that way.
- *
- * The human readable log message directly follows the message header. The
- * length of the message text is stored in the header, the stored message
- * is not terminated.
- *
- * Optionally, a message can carry a dictionary of properties (key/value pairs),
- * to provide userspace with a machine-readable message context.
+ * Optionally, a record can carry a dictionary of properties (key/value
+ * pairs), to provide userspace with a machine-readable message context.
*
* Examples for well-defined, commonly used property names are:
* DEVICE=b12:8 device identifier
@@ -335,25 +306,22 @@
* +sound:card0 subsystem:devname
* SUBSYSTEM=pci driver-core subsystem name
*
- * Valid characters in property names are [a-zA-Z0-9.-_]. The plain text value
- * follows directly after a '=' character. Every property is terminated by
- * a '\0' character. The last property is not terminated.
+ * Valid characters in property names are [a-zA-Z0-9.-_]. Property names
+ * and values are terminated by a '\0' character.
*
- * Example of a message structure:
- * 0000 ff 8f 00 00 00 00 00 00 monotonic time in nsec
- * 0008 34 00 record is 52 bytes long
- * 000a 0b 00 text is 11 bytes long
- * 000c 1f 00 dictionary is 23 bytes long
- * 000e 03 00 LOG_KERN (facility) LOG_ERR (level)
- * 0010 69 74 27 73 20 61 20 6c "it's a l"
- * 69 6e 65 "ine"
- * 001b 44 45 56 49 43 "DEVIC"
- * 45 3d 62 38 3a 32 00 44 "E=b8:2\0D"
- * 52 49 56 45 52 3d 62 75 "RIVER=bu"
- * 67 "g"
- * 0032 00 00 00 padding to next message header
+ * Example of record values:
+ * record.text_buf = "it's a line" (unterminated)
+ * record.info.seq = 56
+ * record.info.ts_nsec = 36863
+ * record.info.text_len = 11
+ * record.info.facility = 0 (LOG_KERN)
+ * record.info.flags = 0
+ * record.info.level = 3 (LOG_ERR)
+ * record.info.caller_id = 299 (task 299)
+ * record.info.dev_info.subsystem = "pci" (terminated)
+ * record.info.dev_info.device = "+pci:0000:00:01.0" (terminated)
*
- * The 'struct printk_log' buffer header must never be directly exported to
+ * The 'struct printk_info' buffer must never be directly exported to
* userspace, it is a kernel-private implementation detail that might
* need to be changed in the future, when the requirements change.
*
@@ -370,106 +338,75 @@
enum log_flags {
LOG_NEWLINE = 2, /* text ended with a newline */
- LOG_PREFIX = 4, /* text started with a prefix */
LOG_CONT = 8, /* text is a fragment of a continuation line */
};
-struct printk_log {
- u64 ts_nsec; /* timestamp in nanoseconds */
- u16 len; /* length of entire record */
- u16 text_len; /* length of text buffer */
- u16 dict_len; /* length of dictionary buffer */
- u8 facility; /* syslog facility */
- u8 flags:5; /* internal record flags */
- u8 level:3; /* syslog level */
-#ifdef CONFIG_PRINTK_PROCESS
- char process[16]; /* process name */
- pid_t pid; /* process id */
- u8 cpu; /* cpu id */
- u8 in_interrupt; /* interrupt context */
-#endif
-}
-#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
-__packed __aligned(4)
-#endif
-;
-
-/*
- * The logbuf_lock protects kmsg buffer, indices, counters. This can be taken
- * within the scheduler's rq lock. It must be released before calling
- * console_unlock() or anything else that might wake up a process.
- */
-DEFINE_RAW_SPINLOCK(logbuf_lock);
-
-/*
- * Helper macros to lock/unlock logbuf_lock and switch between
- * printk-safe/unsafe modes.
- */
-#define logbuf_lock_irq() \
- do { \
- printk_safe_enter_irq(); \
- raw_spin_lock(&logbuf_lock); \
- } while (0)
-
-#define logbuf_unlock_irq() \
- do { \
- raw_spin_unlock(&logbuf_lock); \
- printk_safe_exit_irq(); \
- } while (0)
-
-#define logbuf_lock_irqsave(flags) \
- do { \
- printk_safe_enter_irqsave(flags); \
- raw_spin_lock(&logbuf_lock); \
- } while (0)
-
-#define logbuf_unlock_irqrestore(flags) \
- do { \
- raw_spin_unlock(&logbuf_lock); \
- printk_safe_exit_irqrestore(flags); \
- } while (0)
-
#ifdef CONFIG_PRINTK
+/* syslog_lock protects syslog_* variables and write access to clear_seq. */
+static DEFINE_SPINLOCK(syslog_lock);
+
+/* Set to enable sync mode. Once set, it is never cleared. */
+static bool sync_mode;
+
DECLARE_WAIT_QUEUE_HEAD(log_wait);
+/* All 3 protected by @syslog_lock. */
/* the next printk record to read by syslog(READ) or /proc/kmsg */
static u64 syslog_seq;
-static u32 syslog_idx;
static size_t syslog_partial;
+static bool syslog_time;
-/* index and sequence number of the first record stored in the buffer */
-static u64 log_first_seq;
-static u32 log_first_idx;
+struct latched_seq {
+ seqcount_latch_t latch;
+ u64 val[2];
+};
-/* index and sequence number of the next record to store in the buffer */
-static u64 log_next_seq;
-static u32 log_next_idx;
+/*
+ * The next printk record to read after the last 'clear' command. There are
+ * two copies (updated with seqcount_latch) so that reads can locklessly
+ * access a valid value. Writers are synchronized by @syslog_lock.
+ */
+static struct latched_seq clear_seq = {
+ .latch = SEQCNT_LATCH_ZERO(clear_seq.latch),
+ .val[0] = 0,
+ .val[1] = 0,
+};
-/* the next printk record to write to the console */
-static u64 console_seq;
-static u32 console_idx;
-static u64 exclusive_console_stop_seq;
-
-/* the next printk record to read after the last 'clear' command */
-static u64 clear_seq;
-static u32 clear_idx;
-
-#ifdef CONFIG_PRINTK_PROCESS
+#ifdef CONFIG_PRINTK_CALLER
#define PREFIX_MAX 48
#else
#define PREFIX_MAX 32
#endif
+
+/* the maximum size allowed to be reserved for a record */
#define LOG_LINE_MAX (1024 - PREFIX_MAX)
#define LOG_LEVEL(v) ((v) & 0x07)
#define LOG_FACILITY(v) ((v) >> 3 & 0xff)
/* record buffer */
-#define LOG_ALIGN __alignof__(struct printk_log)
+#define LOG_ALIGN __alignof__(unsigned long)
#define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT)
#define LOG_BUF_LEN_MAX (u32)(1 << 31)
static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN);
static char *log_buf = __log_buf;
static u32 log_buf_len = __LOG_BUF_LEN;
+
+/*
+ * Define the average message size. This only affects the number of
+ * descriptors that will be available. Underestimating is better than
+ * overestimating (too many available descriptors is better than not enough).
+ */
+#define PRB_AVGBITS 5 /* 32 character average length */
+
+#if CONFIG_LOG_BUF_SHIFT <= PRB_AVGBITS
+#error CONFIG_LOG_BUF_SHIFT value too small.
+#endif
+_DEFINE_PRINTKRB(printk_rb_static, CONFIG_LOG_BUF_SHIFT - PRB_AVGBITS,
+ PRB_AVGBITS, &__log_buf[0]);
+
+static struct printk_ringbuffer printk_rb_dynamic;
+
+static struct printk_ringbuffer *prb = &printk_rb_static;
/*
* We cannot access per-CPU data (e.g. per-CPU flush irq_work) before
@@ -478,9 +415,34 @@
*/
static bool __printk_percpu_data_ready __read_mostly;
-bool printk_percpu_data_ready(void)
+static bool printk_percpu_data_ready(void)
{
return __printk_percpu_data_ready;
+}
+
+/* Must be called under syslog_lock. */
+static void latched_seq_write(struct latched_seq *ls, u64 val)
+{
+ raw_write_seqcount_latch(&ls->latch);
+ ls->val[0] = val;
+ raw_write_seqcount_latch(&ls->latch);
+ ls->val[1] = val;
+}
+
+/* Can be called from any context. */
+static u64 latched_seq_read_nolock(struct latched_seq *ls)
+{
+ unsigned int seq;
+ unsigned int idx;
+ u64 val;
+
+ do {
+ seq = raw_read_seqcount_latch(&ls->latch);
+ idx = seq & 0x1;
+ val = ls->val[idx];
+ } while (read_seqcount_latch_retry(&ls->latch, seq));
+
+ return val;
}
/* Return log buffer address */
@@ -497,127 +459,6 @@
}
EXPORT_SYMBOL_GPL(log_buf_len_get);
-/* human readable text of the record */
-static char *log_text(const struct printk_log *msg)
-{
- return (char *)msg + sizeof(struct printk_log);
-}
-
-/* optional key/value pair dictionary attached to the record */
-static char *log_dict(const struct printk_log *msg)
-{
- return (char *)msg + sizeof(struct printk_log) + msg->text_len;
-}
-
-/* get record by index; idx must point to valid msg */
-static struct printk_log *log_from_idx(u32 idx)
-{
- struct printk_log *msg = (struct printk_log *)(log_buf + idx);
-
- /*
- * A length == 0 record is the end of buffer marker. Wrap around and
- * read the message at the start of the buffer.
- */
- if (!msg->len)
- return (struct printk_log *)log_buf;
- return msg;
-}
-
-/* get next record; idx must point to valid msg */
-static u32 log_next(u32 idx)
-{
- struct printk_log *msg = (struct printk_log *)(log_buf + idx);
-
- /* length == 0 indicates the end of the buffer; wrap */
- /*
- * A length == 0 record is the end of buffer marker. Wrap around and
- * read the message at the start of the buffer as *this* one, and
- * return the one after that.
- */
- if (!msg->len) {
- msg = (struct printk_log *)log_buf;
- return msg->len;
- }
- return idx + msg->len;
-}
-
-#ifdef CONFIG_PRINTK_PROCESS
-static bool printk_process = true;
-static size_t print_process(const struct printk_log *msg, char *buf)
-{
- if (!printk_process)
- return 0;
-
- if (!buf)
- return snprintf(NULL, 0, "%c[%1d:%15s:%5d] ", ' ', 0, " ", 0);
-
- return sprintf(buf, "%c[%1d:%15s:%5d] ",
- msg->in_interrupt ? 'I' : ' ',
- msg->cpu,
- msg->process,
- msg->pid);
-}
-module_param_named(process, printk_process, bool, 0644);
-#endif
-
-/*
- * Check whether there is enough free space for the given message.
- *
- * The same values of first_idx and next_idx mean that the buffer
- * is either empty or full.
- *
- * If the buffer is empty, we must respect the position of the indexes.
- * They cannot be reset to the beginning of the buffer.
- */
-static int logbuf_has_space(u32 msg_size, bool empty)
-{
- u32 free;
-
- if (log_next_idx > log_first_idx || empty)
- free = max(log_buf_len - log_next_idx, log_first_idx);
- else
- free = log_first_idx - log_next_idx;
-
- /*
- * We need space also for an empty header that signalizes wrapping
- * of the buffer.
- */
- return free >= msg_size + sizeof(struct printk_log);
-}
-
-static int log_make_free_space(u32 msg_size)
-{
- while (log_first_seq < log_next_seq &&
- !logbuf_has_space(msg_size, false)) {
- /* drop old messages until we have enough contiguous space */
- log_first_idx = log_next(log_first_idx);
- log_first_seq++;
- }
-
- if (clear_seq < log_first_seq) {
- clear_seq = log_first_seq;
- clear_idx = log_first_idx;
- }
-
- /* sequence numbers are equal, so the log buffer is empty */
- if (logbuf_has_space(msg_size, log_first_seq == log_next_seq))
- return 0;
-
- return -ENOMEM;
-}
-
-/* compute the message size including the padding bytes */
-static u32 msg_used_size(u16 text_len, u16 dict_len, u32 *pad_len)
-{
- u32 size;
-
- size = sizeof(struct printk_log) + text_len + dict_len;
- *pad_len = (-size) & (LOG_ALIGN - 1);
- size += *pad_len;
-
- return size;
-}
-
/*
* Define how much of the log buffer we could take at maximum. The value
* must be greater than two. Note that only half of the buffer is available
@@ -626,91 +467,23 @@
#define MAX_LOG_TAKE_PART 4
static const char trunc_msg[] = "<truncated>";
-static u32 truncate_msg(u16 *text_len, u16 *trunc_msg_len,
- u16 *dict_len, u32 *pad_len)
+static void truncate_msg(u16 *text_len, u16 *trunc_msg_len)
{
/*
* The message should not take the whole buffer. Otherwise, it might
* get removed too soon.
*/
u32 max_text_len = log_buf_len / MAX_LOG_TAKE_PART;
+
if (*text_len > max_text_len)
*text_len = max_text_len;
- /* enable the warning message */
+
+ /* enable the warning message (if there is room) */
*trunc_msg_len = strlen(trunc_msg);
- /* disable the "dict" completely */
- *dict_len = 0;
- /* compute the size again, count also the warning message */
- return msg_used_size(*text_len + *trunc_msg_len, 0, pad_len);
-}
-
-/* insert record into the buffer, discard old ones, update heads */
-static int log_store(int facility, int level,
- enum log_flags flags, u64 ts_nsec,
- const char *dict, u16 dict_len,
- const char *text, u16 text_len)
-{
- struct printk_log *msg;
- u32 size, pad_len;
- u16 trunc_msg_len = 0;
-
- /* number of '\0' padding bytes to next message */
- size = msg_used_size(text_len, dict_len, &pad_len);
-
- if (log_make_free_space(size)) {
- /* truncate the message if it is too long for empty buffer */
- size = truncate_msg(&text_len, &trunc_msg_len,
- &dict_len, &pad_len);
- /* survive when the log buffer is too small for trunc_msg */
- if (log_make_free_space(size))
- return 0;
- }
-
- if (log_next_idx + size + sizeof(struct printk_log) > log_buf_len) {
- /*
- * This message + an additional empty header does not fit
- * at the end of the buffer. Add an empty header with len == 0
- * to signify a wrap around.
- */
- memset(log_buf + log_next_idx, 0, sizeof(struct printk_log));
- log_next_idx = 0;
- }
-
- /* fill message */
- msg = (struct printk_log *)(log_buf + log_next_idx);
- memcpy(log_text(msg), text, text_len);
- msg->text_len = text_len;
- if (trunc_msg_len) {
- memcpy(log_text(msg) + text_len, trunc_msg, trunc_msg_len);
- msg->text_len += trunc_msg_len;
- }
- memcpy(log_dict(msg), dict, dict_len);
- msg->dict_len = dict_len;
- msg->facility = facility;
- msg->level = level & 7;
- msg->flags = flags & 0x1f;
- if (ts_nsec > 0)
- msg->ts_nsec = ts_nsec;
+ if (*text_len >= *trunc_msg_len)
+ *text_len -= *trunc_msg_len;
else
- msg->ts_nsec = get_local_clock();
- memset(log_dict(msg) + dict_len, 0, pad_len);
- msg->len = size;
-
-#ifdef CONFIG_PRINTK_PROCESS
- if (printk_process) {
- strncpy(msg->process, current->comm, sizeof(msg->process) - 1);
- msg->process[sizeof(msg->process) - 1] = '\0';
- msg->pid = task_pid_nr(current);
- msg->cpu = raw_smp_processor_id();
- msg->in_interrupt = in_interrupt() ? 1 : 0;
- }
-#endif
-
- /* insert message */
- log_next_idx += msg->len;
- log_next_seq++;
-
- return msg->text_len;
+ *trunc_msg_len = 0;
}
int dmesg_restrict = IS_ENABLED(CONFIG_SECURITY_DMESG_RESTRICT);
@@ -762,21 +535,30 @@
*(*pp)++ = c;
}
-static ssize_t msg_print_ext_header(char *buf, size_t size,
- struct printk_log *msg, u64 seq)
+static ssize_t info_print_ext_header(char *buf, size_t size,
+ struct printk_info *info)
{
- u64 ts_usec = msg->ts_nsec;
+ u64 ts_usec = info->ts_nsec;
+ char caller[20];
+#ifdef CONFIG_PRINTK_CALLER
+ u32 id = info->caller_id;
+
+ snprintf(caller, sizeof(caller), ",caller=%c%u",
+ id & 0x80000000 ? 'C' : 'T', id & ~0x80000000);
+#else
+ caller[0] = '\0';
+#endif
do_div(ts_usec, 1000);
- return scnprintf(buf, size, "%u,%llu,%llu,%c;",
- (msg->facility << 3) | msg->level, seq, ts_usec,
- msg->flags & LOG_CONT ? 'c' : '-');
+ return scnprintf(buf, size, "%u,%llu,%llu,%c%s;",
+ (info->facility << 3) | info->level, info->seq,
+ ts_usec, info->flags & LOG_CONT ? 'c' : '-', caller);
}
-static ssize_t msg_print_ext_body(char *buf, size_t size,
- char *dict, size_t dict_len,
- char *text, size_t text_len)
+static ssize_t msg_add_ext_text(char *buf, size_t size,
+ const char *text, size_t text_len,
+ unsigned char endc)
{
char *p = buf, *e = buf + size;
size_t i;
@@ -790,46 +572,70 @@
else
append_char(&p, e, c);
}
- append_char(&p, e, '\n');
-
- if (dict_len) {
- bool line = true;
-
- for (i = 0; i < dict_len; i++) {
- unsigned char c = dict[i];
-
- if (line) {
- append_char(&p, e, ' ');
- line = false;
- }
-
- if (c == '\0') {
- append_char(&p, e, '\n');
- line = true;
- continue;
- }
-
- if (c < ' ' || c >= 127 || c == '\\') {
- p += scnprintf(p, e - p, "\\x%02x", c);
- continue;
- }
-
- append_char(&p, e, c);
- }
- append_char(&p, e, '\n');
- }
+ append_char(&p, e, endc);
return p - buf;
}
+static ssize_t msg_add_dict_text(char *buf, size_t size,
+ const char *key, const char *val)
+{
+ size_t val_len = strlen(val);
+ ssize_t len;
+
+ if (!val_len)
+ return 0;
+
+ len = msg_add_ext_text(buf, size, "", 0, ' '); /* dict prefix */
+ len += msg_add_ext_text(buf + len, size - len, key, strlen(key), '=');
+ len += msg_add_ext_text(buf + len, size - len, val, val_len, '\n');
+
+ return len;
+}
+
+static ssize_t msg_print_ext_body(char *buf, size_t size,
+ char *text, size_t text_len,
+ struct dev_printk_info *dev_info)
+{
+ ssize_t len;
+
+ len = msg_add_ext_text(buf, size, text, text_len, '\n');
+
+ if (!dev_info)
+ goto out;
+
+ len += msg_add_dict_text(buf + len, size - len, "SUBSYSTEM",
+ dev_info->subsystem);
+ len += msg_add_dict_text(buf + len, size - len, "DEVICE",
+ dev_info->device);
+out:
+ return len;
+}
+
/* /dev/kmsg - userspace message inject/listen interface */
struct devkmsg_user {
- u64 seq;
- u32 idx;
+ atomic64_t seq;
struct ratelimit_state rs;
struct mutex lock;
char buf[CONSOLE_EXT_LOG_MAX];
+
+ struct printk_info info;
+ char text_buf[CONSOLE_EXT_LOG_MAX];
+ struct printk_record record;
};
+
+static __printf(3, 4) __cold
+int devkmsg_emit(int facility, int level, const char *fmt, ...)
+{
+ va_list args;
+ int r;
+
+ va_start(args, fmt);
+ r = vprintk_emit(facility, level, NULL, fmt, args);
+ va_end(args);
+
+ return r;
+}
static ssize_t devkmsg_write(struct kiocb *iocb, struct iov_iter *from)
{
@@ -889,7 +695,7 @@
}
}
- printk_emit(facility, level, NULL, 0, "%s", line);
+ devkmsg_emit(facility, level, "%s", line);
kfree(buf);
return ret;
}
@@ -898,7 +704,7 @@
size_t count, loff_t *ppos)
{
struct devkmsg_user *user = file->private_data;
- struct printk_log *msg;
+ struct printk_record *r = &user->record;
size_t len;
ssize_t ret;
@@ -909,41 +715,31 @@
if (ret)
return ret;
- logbuf_lock_irq();
- while (user->seq == log_next_seq) {
+ if (!prb_read_valid(prb, atomic64_read(&user->seq), r)) {
if (file->f_flags & O_NONBLOCK) {
ret = -EAGAIN;
- logbuf_unlock_irq();
goto out;
}
- logbuf_unlock_irq();
ret = wait_event_interruptible(log_wait,
- user->seq != log_next_seq);
+ prb_read_valid(prb, atomic64_read(&user->seq), r));
if (ret)
goto out;
- logbuf_lock_irq();
}
- if (user->seq < log_first_seq) {
+ if (r->info->seq != atomic64_read(&user->seq)) {
/* our last seen message is gone, return error and reset */
- user->idx = log_first_idx;
- user->seq = log_first_seq;
+ atomic64_set(&user->seq, r->info->seq);
ret = -EPIPE;
- logbuf_unlock_irq();
goto out;
}
- msg = log_from_idx(user->idx);
- len = msg_print_ext_header(user->buf, sizeof(user->buf),
- msg, user->seq);
+ len = info_print_ext_header(user->buf, sizeof(user->buf), r->info);
len += msg_print_ext_body(user->buf + len, sizeof(user->buf) - len,
- log_dict(msg), msg->dict_len,
- log_text(msg), msg->text_len);
+ &r->text_buf[0], r->info->text_len,
+ &r->info->dev_info);
- user->idx = log_next(user->idx);
- user->seq++;
- logbuf_unlock_irq();
+ atomic64_set(&user->seq, r->info->seq + 1);
if (len > count) {
ret = -EINVAL;
@@ -960,6 +756,14 @@
return ret;
}
+/*
+ * Be careful when modifying this function!!!
+ *
+ * Only few operations are supported because the device works only with the
+ * entire variable length messages (records). Non-standard values are
+ * returned in the other cases and has been this way for quite some time.
+ * User space applications might depend on this behavior.
+ */
static loff_t devkmsg_llseek(struct file *file, loff_t offset, int whence)
{
struct devkmsg_user *user = file->private_data;
@@ -970,12 +774,10 @@
if (offset)
return -ESPIPE;
- logbuf_lock_irq();
switch (whence) {
case SEEK_SET:
/* the first record */
- user->idx = log_first_idx;
- user->seq = log_first_seq;
+ atomic64_set(&user->seq, prb_first_valid_seq(prb));
break;
case SEEK_DATA:
/*
@@ -983,24 +785,22 @@
* like issued by 'dmesg -c'. Reading /dev/kmsg itself
* changes no global state, and does not clear anything.
*/
- user->idx = clear_idx;
- user->seq = clear_seq;
+ atomic64_set(&user->seq, latched_seq_read_nolock(&clear_seq));
break;
case SEEK_END:
/* after the last record */
- user->idx = log_next_idx;
- user->seq = log_next_seq;
+ atomic64_set(&user->seq, prb_next_seq(prb));
break;
default:
ret = -EINVAL;
}
- logbuf_unlock_irq();
return ret;
}
static __poll_t devkmsg_poll(struct file *file, poll_table *wait)
{
struct devkmsg_user *user = file->private_data;
+ struct printk_info info;
__poll_t ret = 0;
if (!user)
@@ -1008,15 +808,13 @@
poll_wait(file, &log_wait, wait);
- logbuf_lock_irq();
- if (user->seq < log_next_seq) {
+ if (prb_read_valid_info(prb, atomic64_read(&user->seq), &info, NULL)) {
/* return error when data has vanished underneath us */
- if (user->seq < log_first_seq)
+ if (info.seq != atomic64_read(&user->seq))
ret = EPOLLIN|EPOLLRDNORM|EPOLLERR|EPOLLPRI;
else
ret = EPOLLIN|EPOLLRDNORM;
}
- logbuf_unlock_irq();
return ret;
}
@@ -1046,10 +844,10 @@
mutex_init(&user->lock);
- logbuf_lock_irq();
- user->idx = log_first_idx;
- user->seq = log_first_seq;
- logbuf_unlock_irq();
+ prb_rec_init_rd(&user->record, &user->info,
+ &user->text_buf[0], sizeof(user->text_buf));
+
+ atomic64_set(&user->seq, prb_first_valid_seq(prb));
file->private_data = user;
return 0;
@@ -1089,20 +887,61 @@
*/
void log_buf_vmcoreinfo_setup(void)
{
- VMCOREINFO_SYMBOL(log_buf);
- VMCOREINFO_SYMBOL(log_buf_len);
- VMCOREINFO_SYMBOL(log_first_idx);
- VMCOREINFO_SYMBOL(clear_idx);
- VMCOREINFO_SYMBOL(log_next_idx);
+ struct dev_printk_info *dev_info = NULL;
+
+ VMCOREINFO_SYMBOL(prb);
+ VMCOREINFO_SYMBOL(printk_rb_static);
+ VMCOREINFO_SYMBOL(clear_seq);
+
/*
- * Export struct printk_log size and field offsets. User space tools can
+ * Export struct size and field offsets. User space tools can
* parse it and detect any changes to structure down the line.
*/
- VMCOREINFO_STRUCT_SIZE(printk_log);
- VMCOREINFO_OFFSET(printk_log, ts_nsec);
- VMCOREINFO_OFFSET(printk_log, len);
- VMCOREINFO_OFFSET(printk_log, text_len);
- VMCOREINFO_OFFSET(printk_log, dict_len);
+
+ VMCOREINFO_STRUCT_SIZE(printk_ringbuffer);
+ VMCOREINFO_OFFSET(printk_ringbuffer, desc_ring);
+ VMCOREINFO_OFFSET(printk_ringbuffer, text_data_ring);
+ VMCOREINFO_OFFSET(printk_ringbuffer, fail);
+
+ VMCOREINFO_STRUCT_SIZE(prb_desc_ring);
+ VMCOREINFO_OFFSET(prb_desc_ring, count_bits);
+ VMCOREINFO_OFFSET(prb_desc_ring, descs);
+ VMCOREINFO_OFFSET(prb_desc_ring, infos);
+ VMCOREINFO_OFFSET(prb_desc_ring, head_id);
+ VMCOREINFO_OFFSET(prb_desc_ring, tail_id);
+
+ VMCOREINFO_STRUCT_SIZE(prb_desc);
+ VMCOREINFO_OFFSET(prb_desc, state_var);
+ VMCOREINFO_OFFSET(prb_desc, text_blk_lpos);
+
+ VMCOREINFO_STRUCT_SIZE(prb_data_blk_lpos);
+ VMCOREINFO_OFFSET(prb_data_blk_lpos, begin);
+ VMCOREINFO_OFFSET(prb_data_blk_lpos, next);
+
+ VMCOREINFO_STRUCT_SIZE(printk_info);
+ VMCOREINFO_OFFSET(printk_info, seq);
+ VMCOREINFO_OFFSET(printk_info, ts_nsec);
+ VMCOREINFO_OFFSET(printk_info, text_len);
+ VMCOREINFO_OFFSET(printk_info, caller_id);
+ VMCOREINFO_OFFSET(printk_info, dev_info);
+
+ VMCOREINFO_STRUCT_SIZE(dev_printk_info);
+ VMCOREINFO_OFFSET(dev_printk_info, subsystem);
+ VMCOREINFO_LENGTH(printk_info_subsystem, sizeof(dev_info->subsystem));
+ VMCOREINFO_OFFSET(dev_printk_info, device);
+ VMCOREINFO_LENGTH(printk_info_device, sizeof(dev_info->device));
+
+ VMCOREINFO_STRUCT_SIZE(prb_data_ring);
+ VMCOREINFO_OFFSET(prb_data_ring, size_bits);
+ VMCOREINFO_OFFSET(prb_data_ring, data);
+ VMCOREINFO_OFFSET(prb_data_ring, head_lpos);
+ VMCOREINFO_OFFSET(prb_data_ring, tail_lpos);
+
+ VMCOREINFO_SIZE(atomic_long_t);
+ VMCOREINFO_TYPE_OFFSET(atomic_long_t, counter);
+
+ VMCOREINFO_STRUCT_SIZE(latched_seq);
+ VMCOREINFO_OFFSET(latched_seq, val);
}
#endif
@@ -1174,17 +1013,48 @@
static void __init set_percpu_data_ready(void)
{
- printk_safe_init();
- /* Make sure we set this flag only after printk_safe() init is done */
- barrier();
__printk_percpu_data_ready = true;
}
+static unsigned int __init add_to_rb(struct printk_ringbuffer *rb,
+ struct printk_record *r)
+{
+ struct prb_reserved_entry e;
+ struct printk_record dest_r;
+
+ prb_rec_init_wr(&dest_r, r->info->text_len);
+
+ if (!prb_reserve(&e, rb, &dest_r))
+ return 0;
+
+ memcpy(&dest_r.text_buf[0], &r->text_buf[0], r->info->text_len);
+ dest_r.info->text_len = r->info->text_len;
+ dest_r.info->facility = r->info->facility;
+ dest_r.info->level = r->info->level;
+ dest_r.info->flags = r->info->flags;
+ dest_r.info->ts_nsec = r->info->ts_nsec;
+ dest_r.info->caller_id = r->info->caller_id;
+ memcpy(&dest_r.info->dev_info, &r->info->dev_info, sizeof(dest_r.info->dev_info));
+
+ prb_final_commit(&e);
+
+ return prb_record_text_space(&e);
+}
+
+static char setup_text_buf[LOG_LINE_MAX] __initdata;
+
void __init setup_log_buf(int early)
{
- unsigned long flags;
+ struct printk_info *new_infos;
+ unsigned int new_descs_count;
+ struct prb_desc *new_descs;
+ struct printk_info info;
+ struct printk_record r;
+ size_t new_descs_size;
+ size_t new_infos_size;
char *new_log_buf;
unsigned int free;
+ u64 seq;
/*
* Some archs call setup_log_buf() multiple times - first is very
@@ -1203,38 +1073,74 @@
if (!new_log_buf_len)
return;
- if (early) {
- new_log_buf =
- memblock_virt_alloc(new_log_buf_len, LOG_ALIGN);
- } else {
- new_log_buf = memblock_virt_alloc_nopanic(new_log_buf_len,
- LOG_ALIGN);
- }
-
- if (unlikely(!new_log_buf)) {
- pr_err("log_buf_len: %lu bytes not available\n",
- new_log_buf_len);
+ new_descs_count = new_log_buf_len >> PRB_AVGBITS;
+ if (new_descs_count == 0) {
+ pr_err("new_log_buf_len: %lu too small\n", new_log_buf_len);
return;
}
- logbuf_lock_irqsave(flags);
+ new_log_buf = memblock_alloc(new_log_buf_len, LOG_ALIGN);
+ if (unlikely(!new_log_buf)) {
+ pr_err("log_buf_len: %lu text bytes not available\n",
+ new_log_buf_len);
+ return;
+ }
+
+ new_descs_size = new_descs_count * sizeof(struct prb_desc);
+ new_descs = memblock_alloc(new_descs_size, LOG_ALIGN);
+ if (unlikely(!new_descs)) {
+ pr_err("log_buf_len: %zu desc bytes not available\n",
+ new_descs_size);
+ goto err_free_log_buf;
+ }
+
+ new_infos_size = new_descs_count * sizeof(struct printk_info);
+ new_infos = memblock_alloc(new_infos_size, LOG_ALIGN);
+ if (unlikely(!new_infos)) {
+ pr_err("log_buf_len: %zu info bytes not available\n",
+ new_infos_size);
+ goto err_free_descs;
+ }
+
+ prb_rec_init_rd(&r, &info, &setup_text_buf[0], sizeof(setup_text_buf));
+
+ prb_init(&printk_rb_dynamic,
+ new_log_buf, ilog2(new_log_buf_len),
+ new_descs, ilog2(new_descs_count),
+ new_infos);
+
log_buf_len = new_log_buf_len;
log_buf = new_log_buf;
new_log_buf_len = 0;
- free = __LOG_BUF_LEN - log_next_idx;
- memcpy(log_buf, __log_buf, __LOG_BUF_LEN);
- logbuf_unlock_irqrestore(flags);
+
+ free = __LOG_BUF_LEN;
+ prb_for_each_record(0, &printk_rb_static, seq, &r)
+ free -= add_to_rb(&printk_rb_dynamic, &r);
+
+ /*
+ * This is early enough that everything is still running on the
+ * boot CPU and interrupts are disabled. So no new messages will
+ * appear during the transition to the dynamic buffer.
+ */
+ prb = &printk_rb_dynamic;
+
+ if (seq != prb_next_seq(&printk_rb_static)) {
+ pr_err("dropped %llu messages\n",
+ prb_next_seq(&printk_rb_static) - seq);
+ }
pr_info("log_buf_len: %u bytes\n", log_buf_len);
pr_info("early log buf free: %u(%u%%)\n",
free, (free * 100) / __LOG_BUF_LEN);
+ return;
+
+err_free_descs:
+ memblock_free(__pa(new_descs), new_descs_size);
+err_free_log_buf:
+ memblock_free(__pa(new_log_buf), new_log_buf_len);
}
-#ifdef CONFIG_PSTORE_CONSOLE_FORCE_ON
-static bool __read_mostly ignore_loglevel = true;
-#else
static bool __read_mostly ignore_loglevel;
-#endif
static int __init ignore_loglevel_setup(char *str)
{
@@ -1248,61 +1154,6 @@
module_param(ignore_loglevel, bool, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(ignore_loglevel,
"ignore loglevel setting (prints all kernel messages to the console)");
-
-#ifdef CONFIG_PSTORE_CONSOLE_FORCE
-static bool __read_mostly pstore_con_force = IS_ENABLED(CONFIG_PSTORE_CONSOLE_FORCE_ON);
-
-static int __init pstore_con_force_setup(char *str)
-{
- bool force;
- int ret = strtobool(str, &force);
-
- if (ret)
- return ret;
-
- ignore_loglevel = force;
- pstore_con_force = force;
- if (force)
- pr_info("debug: pstore console ignoring loglevel setting.\n");
-
- return 0;
-}
-
-early_param("pstore_con_force", pstore_con_force_setup);
-module_param(pstore_con_force, bool, S_IRUGO | S_IWUSR);
-MODULE_PARM_DESC(pstore_con_force,
- "ignore loglevel setting (prints all kernel messages to the pstore console)");
-
-static void call_console_drivers_level(int level, const char *ext_text, size_t ext_len,
- const char *text, size_t len)
-{
- struct console *con;
-
- trace_console_rcuidle(text, len);
-
- if (!console_drivers)
- return;
-
- for_each_console(con) {
- if (pstore_con_force &&
- !(con->flags & CON_PSTORE) && level >= console_loglevel)
- continue;
- if (exclusive_console && con != exclusive_console)
- continue;
- if (!(con->flags & CON_ENABLED))
- continue;
- if (!con->write)
- continue;
- if (!cpu_online(smp_processor_id()) &&
- !(con->flags & CON_ANYTIME))
- continue;
- if (con->flags & CON_EXTENDED)
- con->write(con, ext_text, ext_len);
- else
- con->write(con, text, len);
- }
-}
-#endif
static bool suppress_message_printing(int level)
{
@@ -1367,121 +1218,272 @@
static bool printk_time = IS_ENABLED(CONFIG_PRINTK_TIME);
module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR);
+static size_t print_syslog(unsigned int level, char *buf)
+{
+ return sprintf(buf, "<%u>", level);
+}
+
static size_t print_time(u64 ts, char *buf)
{
- unsigned long rem_nsec;
+ unsigned long rem_nsec = do_div(ts, 1000000000);
- if (!printk_time)
- return 0;
-
- rem_nsec = do_div(ts, 1000000000);
-
- if (!buf)
- return snprintf(NULL, 0, "[%5lu.000000] ", (unsigned long)ts);
-
- return sprintf(buf, "[%5lu.%06lu] ",
+ return sprintf(buf, "[%5lu.%06lu]",
(unsigned long)ts, rem_nsec / 1000);
}
-static size_t print_prefix(const struct printk_log *msg, bool syslog, char *buf)
+#ifdef CONFIG_PRINTK_CALLER
+static size_t print_caller(u32 id, char *buf)
+{
+ char caller[12];
+
+ snprintf(caller, sizeof(caller), "%c%u",
+ id & 0x80000000 ? 'C' : 'T', id & ~0x80000000);
+ return sprintf(buf, "[%6s]", caller);
+}
+#else
+#define print_caller(id, buf) 0
+#endif
+
+static size_t info_print_prefix(const struct printk_info *info, bool syslog,
+ bool time, char *buf)
{
size_t len = 0;
- unsigned int prefix = (msg->facility << 3) | msg->level;
- if (syslog) {
- if (buf) {
- len += sprintf(buf, "<%u>", prefix);
- } else {
- len += 3;
- if (prefix > 999)
- len += 3;
- else if (prefix > 99)
- len += 2;
- else if (prefix > 9)
- len++;
- }
+ if (syslog)
+ len = print_syslog((info->facility << 3) | info->level, buf);
+
+ if (time)
+ len += print_time(info->ts_nsec, buf + len);
+
+ len += print_caller(info->caller_id, buf + len);
+
+ if (IS_ENABLED(CONFIG_PRINTK_CALLER) || time) {
+ buf[len++] = ' ';
+ buf[len] = '\0';
}
- len += print_time(msg->ts_nsec, buf ? buf + len : NULL);
-#ifdef CONFIG_PRINTK_PROCESS
- len += print_process(msg, buf ? buf + len : NULL);
-#endif
return len;
}
-static size_t msg_print_text(const struct printk_log *msg, bool syslog, char *buf, size_t size)
+/*
+ * Prepare the record for printing. The text is shifted within the given
+ * buffer to avoid a need for another one. The following operations are
+ * done:
+ *
+ * - Add prefix for each line.
+ * - Drop truncated lines that no longer fit into the buffer.
+ * - Add the trailing newline that has been removed in vprintk_store().
+ * - Add a string terminator.
+ *
+ * Since the produced string is always terminated, the maximum possible
+ * return value is @r->text_buf_size - 1;
+ *
+ * Return: The length of the updated/prepared text, including the added
+ * prefixes and the newline. The terminator is not counted. The dropped
+ * line(s) are not counted.
+ */
+static size_t record_print_text(struct printk_record *r, bool syslog,
+ bool time)
{
- const char *text = log_text(msg);
- size_t text_size = msg->text_len;
+ size_t text_len = r->info->text_len;
+ size_t buf_size = r->text_buf_size;
+ char *text = r->text_buf;
+ char prefix[PREFIX_MAX];
+ bool truncated = false;
+ size_t prefix_len;
+ size_t line_len;
size_t len = 0;
+ char *next;
- do {
- const char *next = memchr(text, '\n', text_size);
- size_t text_len;
+ /*
+ * If the message was truncated because the buffer was not large
+ * enough, treat the available text as if it were the full text.
+ */
+ if (text_len > buf_size)
+ text_len = buf_size;
+ prefix_len = info_print_prefix(r->info, syslog, time, prefix);
+
+ /*
+ * @text_len: bytes of unprocessed text
+ * @line_len: bytes of current line _without_ newline
+ * @text: pointer to beginning of current line
+ * @len: number of bytes prepared in r->text_buf
+ */
+ for (;;) {
+ next = memchr(text, '\n', text_len);
if (next) {
- text_len = next - text;
- next++;
- text_size -= next - text;
+ line_len = next - text;
} else {
- text_len = text_size;
+ /* Drop truncated line(s). */
+ if (truncated)
+ break;
+ line_len = text_len;
}
- if (buf) {
- if (print_prefix(msg, syslog, NULL) +
- text_len + 1 >= size - len)
+ /*
+ * Truncate the text if there is not enough space to add the
+ * prefix and a trailing newline and a terminator.
+ */
+ if (len + prefix_len + text_len + 1 + 1 > buf_size) {
+ /* Drop even the current line if no space. */
+ if (len + prefix_len + line_len + 1 + 1 > buf_size)
break;
- len += print_prefix(msg, syslog, buf + len);
- memcpy(buf + len, text, text_len);
- len += text_len;
- buf[len++] = '\n';
- } else {
- /* SYSLOG_ACTION_* buffer size only calculation */
- len += print_prefix(msg, syslog, NULL);
- len += text_len;
- len++;
+ text_len = buf_size - len - prefix_len - 1 - 1;
+ truncated = true;
}
- text = next;
- } while (text);
+ memmove(text + prefix_len, text, text_len);
+ memcpy(text, prefix, prefix_len);
+
+ /*
+ * Increment the prepared length to include the text and
+ * prefix that were just moved+copied. Also increment for the
+ * newline at the end of this line. If this is the last line,
+ * there is no newline, but it will be added immediately below.
+ */
+ len += prefix_len + line_len + 1;
+ if (text_len == line_len) {
+ /*
+ * This is the last line. Add the trailing newline
+ * removed in vprintk_store().
+ */
+ text[prefix_len + line_len] = '\n';
+ break;
+ }
+
+ /*
+ * Advance beyond the added prefix and the related line with
+ * its newline.
+ */
+ text += prefix_len + line_len + 1;
+
+ /*
+ * The remaining text has only decreased by the line with its
+ * newline.
+ *
+ * Note that @text_len can become zero. It happens when @text
+ * ended with a newline (either due to truncation or the
+ * original string ending with "\n\n"). The loop is correctly
+ * repeated and (if not truncated) an empty line with a prefix
+ * will be prepared.
+ */
+ text_len -= line_len + 1;
+ }
+
+ /*
+ * If a buffer was provided, it will be terminated. Space for the
+ * string terminator is guaranteed to be available. The terminator is
+ * not counted in the return value.
+ */
+ if (buf_size > 0)
+ r->text_buf[len] = 0;
return len;
+}
+
+static size_t get_record_print_text_size(struct printk_info *info,
+ unsigned int line_count,
+ bool syslog, bool time)
+{
+ char prefix[PREFIX_MAX];
+ size_t prefix_len;
+
+ prefix_len = info_print_prefix(info, syslog, time, prefix);
+
+ /*
+ * Each line will be preceded with a prefix. The intermediate
+ * newlines are already within the text, but a final trailing
+ * newline will be added.
+ */
+ return ((prefix_len * line_count) + info->text_len + 1);
+}
+
+/*
+ * Beginning with @start_seq, find the first record where it and all following
+ * records up to (but not including) @max_seq fit into @size.
+ *
+ * @max_seq is simply an upper bound and does not need to exist. If the caller
+ * does not require an upper bound, -1 can be used for @max_seq.
+ */
+static u64 find_first_fitting_seq(u64 start_seq, u64 max_seq, size_t size,
+ bool syslog, bool time)
+{
+ struct printk_info info;
+ unsigned int line_count;
+ size_t len = 0;
+ u64 seq;
+
+ /* Determine the size of the records up to @max_seq. */
+ prb_for_each_info(start_seq, prb, seq, &info, &line_count) {
+ if (info.seq >= max_seq)
+ break;
+ len += get_record_print_text_size(&info, line_count, syslog, time);
+ }
+
+ /*
+ * Adjust the upper bound for the next loop to avoid subtracting
+ * lengths that were never added.
+ */
+ if (seq < max_seq)
+ max_seq = seq;
+
+ /*
+ * Move first record forward until length fits into the buffer. Ignore
+ * newest messages that were not counted in the above cycle. Messages
+ * might appear and get lost in the meantime. This is a best effort
+ * that prevents an infinite loop that could occur with a retry.
+ */
+ prb_for_each_info(start_seq, prb, seq, &info, &line_count) {
+ if (len <= size || info.seq >= max_seq)
+ break;
+ len -= get_record_print_text_size(&info, line_count, syslog, time);
+ }
+
+ return seq;
}
static int syslog_print(char __user *buf, int size)
{
+ struct printk_info info;
+ struct printk_record r;
char *text;
- struct printk_log *msg;
int len = 0;
- text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL);
+ text = kmalloc(CONSOLE_LOG_MAX, GFP_KERNEL);
if (!text)
return -ENOMEM;
+
+ prb_rec_init_rd(&r, &info, text, CONSOLE_LOG_MAX);
while (size > 0) {
size_t n;
size_t skip;
- logbuf_lock_irq();
- if (syslog_seq < log_first_seq) {
- /* messages are gone, move to first one */
- syslog_seq = log_first_seq;
- syslog_idx = log_first_idx;
- syslog_partial = 0;
- }
- if (syslog_seq == log_next_seq) {
- logbuf_unlock_irq();
+ spin_lock_irq(&syslog_lock);
+ if (!prb_read_valid(prb, syslog_seq, &r)) {
+ spin_unlock_irq(&syslog_lock);
break;
}
+ if (r.info->seq != syslog_seq) {
+ /* message is gone, move to next valid one */
+ syslog_seq = r.info->seq;
+ syslog_partial = 0;
+ }
+
+ /*
+ * To keep reading/counting partial line consistent,
+ * use printk_time value as of the beginning of a line.
+ */
+ if (!syslog_partial)
+ syslog_time = printk_time;
skip = syslog_partial;
- msg = log_from_idx(syslog_idx);
- n = msg_print_text(msg, true, text, LOG_LINE_MAX + PREFIX_MAX);
+ n = record_print_text(&r, true, syslog_time);
if (n - syslog_partial <= size) {
/* message fits into buffer, move forward */
- syslog_idx = log_next(syslog_idx);
- syslog_seq++;
+ syslog_seq = r.info->seq + 1;
n -= syslog_partial;
syslog_partial = 0;
} else if (!len){
@@ -1490,7 +1492,7 @@
syslog_partial += n;
} else
n = 0;
- logbuf_unlock_irq();
+ spin_unlock_irq(&syslog_lock);
if (!n)
break;
@@ -1512,78 +1514,52 @@
static int syslog_print_all(char __user *buf, int size, bool clear)
{
+ struct printk_info info;
+ struct printk_record r;
char *text;
int len = 0;
- u64 next_seq;
u64 seq;
- u32 idx;
+ bool time;
- text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL);
+ text = kmalloc(CONSOLE_LOG_MAX, GFP_KERNEL);
if (!text)
return -ENOMEM;
- logbuf_lock_irq();
+ time = printk_time;
/*
* Find first record that fits, including all following records,
* into the user-provided buffer for this dump.
*/
- seq = clear_seq;
- idx = clear_idx;
- while (seq < log_next_seq) {
- struct printk_log *msg = log_from_idx(idx);
+ seq = find_first_fitting_seq(latched_seq_read_nolock(&clear_seq), -1,
+ size, true, time);
- len += msg_print_text(msg, true, NULL, 0);
- idx = log_next(idx);
- seq++;
- }
-
- /* move first record forward until length fits into the buffer */
- seq = clear_seq;
- idx = clear_idx;
- while (len > size && seq < log_next_seq) {
- struct printk_log *msg = log_from_idx(idx);
-
- len -= msg_print_text(msg, true, NULL, 0);
- idx = log_next(idx);
- seq++;
- }
-
- /* last message fitting into this dump */
- next_seq = log_next_seq;
+ prb_rec_init_rd(&r, &info, text, CONSOLE_LOG_MAX);
len = 0;
- while (len >= 0 && seq < next_seq) {
- struct printk_log *msg = log_from_idx(idx);
+ prb_for_each_record(seq, prb, seq, &r) {
int textlen;
- textlen = msg_print_text(msg, true, text,
- LOG_LINE_MAX + PREFIX_MAX);
- if (textlen < 0) {
- len = textlen;
+ textlen = record_print_text(&r, true, time);
+
+ if (len + textlen > size) {
+ seq--;
break;
}
- idx = log_next(idx);
- seq++;
- logbuf_unlock_irq();
if (copy_to_user(buf + len, text, textlen))
len = -EFAULT;
else
len += textlen;
- logbuf_lock_irq();
- if (seq < log_first_seq) {
- /* messages are gone, move to next one */
- seq = log_first_seq;
- idx = log_first_idx;
- }
+ if (len < 0)
+ break;
}
if (clear) {
- clear_seq = log_next_seq;
- clear_idx = log_next_idx;
+ spin_lock_irq(&syslog_lock);
+ latched_seq_write(&clear_seq, seq);
+ spin_unlock_irq(&syslog_lock);
}
- logbuf_unlock_irq();
kfree(text);
return len;
@@ -1591,14 +1567,26 @@
static void syslog_clear(void)
{
- logbuf_lock_irq();
- clear_seq = log_next_seq;
- clear_idx = log_next_idx;
- logbuf_unlock_irq();
+ spin_lock_irq(&syslog_lock);
+ latched_seq_write(&clear_seq, prb_next_seq(prb));
+ spin_unlock_irq(&syslog_lock);
+}
+
+/* Return a consistent copy of @syslog_seq. */
+static u64 read_syslog_seq_irq(void)
+{
+ u64 seq;
+
+ spin_lock_irq(&syslog_lock);
+ seq = syslog_seq;
+ spin_unlock_irq(&syslog_lock);
+
+ return seq;
}
int do_syslog(int type, char __user *buf, int len, int source)
{
+ struct printk_info info;
bool clear = false;
static int saved_console_loglevel = LOGLEVEL_DEFAULT;
int error;
@@ -1617,10 +1605,11 @@
return -EINVAL;
if (!len)
return 0;
- if (!access_ok(VERIFY_WRITE, buf, len))
+ if (!access_ok(buf, len))
return -EFAULT;
+
error = wait_event_interruptible(log_wait,
- syslog_seq != log_next_seq);
+ prb_read_valid(prb, read_syslog_seq_irq(), NULL));
if (error)
return error;
error = syslog_print(buf, len);
@@ -1628,14 +1617,14 @@
/* Read/clear last kernel messages */
case SYSLOG_ACTION_READ_CLEAR:
clear = true;
- /* FALL THRU */
+ fallthrough;
/* Read last kernel messages */
case SYSLOG_ACTION_READ_ALL:
if (!buf || len < 0)
return -EINVAL;
if (!len)
return 0;
- if (!access_ok(VERIFY_WRITE, buf, len))
+ if (!access_ok(buf, len))
return -EFAULT;
error = syslog_print_all(buf, len, clear);
break;
@@ -1668,11 +1657,15 @@
break;
/* Number of chars in the log buffer */
case SYSLOG_ACTION_SIZE_UNREAD:
- logbuf_lock_irq();
- if (syslog_seq < log_first_seq) {
+ spin_lock_irq(&syslog_lock);
+ if (!prb_read_valid_info(prb, syslog_seq, &info, NULL)) {
+ /* No unread messages. */
+ spin_unlock_irq(&syslog_lock);
+ return 0;
+ }
+ if (info.seq != syslog_seq) {
/* messages are gone, move to first one */
- syslog_seq = log_first_seq;
- syslog_idx = log_first_idx;
+ syslog_seq = info.seq;
syslog_partial = 0;
}
if (source == SYSLOG_FROM_PROC) {
@@ -1681,21 +1674,21 @@
* for pending data, not the size; return the count of
* records, not the length.
*/
- error = log_next_seq - syslog_seq;
+ error = prb_next_seq(prb) - syslog_seq;
} else {
- u64 seq = syslog_seq;
- u32 idx = syslog_idx;
+ bool time = syslog_partial ? syslog_time : printk_time;
+ unsigned int line_count;
+ u64 seq;
- while (seq < log_next_seq) {
- struct printk_log *msg = log_from_idx(idx);
-
- error += msg_print_text(msg, true, NULL, 0);
- idx = log_next(idx);
- seq++;
+ prb_for_each_info(syslog_seq, prb, seq, &info,
+ &line_count) {
+ error += get_record_print_text_size(&info, line_count,
+ true, time);
+ time = printk_time;
}
error -= syslog_partial;
}
- logbuf_unlock_irq();
+ spin_unlock_irq(&syslog_lock);
break;
/* Size of the log buffer */
case SYSLOG_ACTION_SIZE_BUFFER:
@@ -1714,185 +1707,12 @@
return do_syslog(type, buf, len, SYSLOG_FROM_READER);
}
-/*
- * Special console_lock variants that help to reduce the risk of soft-lockups.
- * They allow to pass console_lock to another printk() call using a busy wait.
- */
-
-#ifdef CONFIG_LOCKDEP
-static struct lockdep_map console_owner_dep_map = {
- .name = "console_owner"
-};
-#endif
-
-static DEFINE_RAW_SPINLOCK(console_owner_lock);
-static struct task_struct *console_owner;
-static bool console_waiter;
-
-/**
- * console_lock_spinning_enable - mark beginning of code where another
- * thread might safely busy wait
- *
- * This basically converts console_lock into a spinlock. This marks
- * the section where the console_lock owner can not sleep, because
- * there may be a waiter spinning (like a spinlock). Also it must be
- * ready to hand over the lock at the end of the section.
- */
-static void console_lock_spinning_enable(void)
-{
- raw_spin_lock(&console_owner_lock);
- console_owner = current;
- raw_spin_unlock(&console_owner_lock);
-
- /* The waiter may spin on us after setting console_owner */
- spin_acquire(&console_owner_dep_map, 0, 0, _THIS_IP_);
-}
-
-/**
- * console_lock_spinning_disable_and_check - mark end of code where another
- * thread was able to busy wait and check if there is a waiter
- *
- * This is called at the end of the section where spinning is allowed.
- * It has two functions. First, it is a signal that it is no longer
- * safe to start busy waiting for the lock. Second, it checks if
- * there is a busy waiter and passes the lock rights to her.
- *
- * Important: Callers lose the lock if there was a busy waiter.
- * They must not touch items synchronized by console_lock
- * in this case.
- *
- * Return: 1 if the lock rights were passed, 0 otherwise.
- */
-static int console_lock_spinning_disable_and_check(void)
-{
- int waiter;
-
- raw_spin_lock(&console_owner_lock);
- waiter = READ_ONCE(console_waiter);
- console_owner = NULL;
- raw_spin_unlock(&console_owner_lock);
-
- if (!waiter) {
- spin_release(&console_owner_dep_map, 1, _THIS_IP_);
- return 0;
- }
-
- /* The waiter is now free to continue */
- WRITE_ONCE(console_waiter, false);
-
- spin_release(&console_owner_dep_map, 1, _THIS_IP_);
-
- /*
- * Hand off console_lock to waiter. The waiter will perform
- * the up(). After this, the waiter is the console_lock owner.
- */
- mutex_release(&console_lock_dep_map, 1, _THIS_IP_);
- return 1;
-}
-
-/**
- * console_trylock_spinning - try to get console_lock by busy waiting
- *
- * This allows to busy wait for the console_lock when the current
- * owner is running in specially marked sections. It means that
- * the current owner is running and cannot reschedule until it
- * is ready to lose the lock.
- *
- * Return: 1 if we got the lock, 0 othrewise
- */
-static int console_trylock_spinning(void)
-{
- struct task_struct *owner = NULL;
- bool waiter;
- bool spin = false;
- unsigned long flags;
-
- if (console_trylock())
- return 1;
-
- printk_safe_enter_irqsave(flags);
-
- raw_spin_lock(&console_owner_lock);
- owner = READ_ONCE(console_owner);
- waiter = READ_ONCE(console_waiter);
- if (!waiter && owner && owner != current) {
- WRITE_ONCE(console_waiter, true);
- spin = true;
- }
- raw_spin_unlock(&console_owner_lock);
-
- /*
- * If there is an active printk() writing to the
- * consoles, instead of having it write our data too,
- * see if we can offload that load from the active
- * printer, and do some printing ourselves.
- * Go into a spin only if there isn't already a waiter
- * spinning, and there is an active printer, and
- * that active printer isn't us (recursive printk?).
- */
- if (!spin) {
- printk_safe_exit_irqrestore(flags);
- return 0;
- }
-
- /* We spin waiting for the owner to release us */
- spin_acquire(&console_owner_dep_map, 0, 0, _THIS_IP_);
- /* Owner will clear console_waiter on hand off */
- while (READ_ONCE(console_waiter))
- cpu_relax();
- spin_release(&console_owner_dep_map, 1, _THIS_IP_);
-
- printk_safe_exit_irqrestore(flags);
- /*
- * The owner passed the console lock to us.
- * Since we did not spin on console lock, annotate
- * this as a trylock. Otherwise lockdep will
- * complain.
- */
- mutex_acquire(&console_lock_dep_map, 0, 1, _THIS_IP_);
-
- return 1;
-}
-
-/*
- * Call the console drivers, asking them to write out
- * log_buf[start] to log_buf[end - 1].
- * The console_lock must be held.
- */
-#ifdef CONFIG_PSTORE_CONSOLE_FORCE
-__maybe_unused
-#endif
-static void call_console_drivers(const char *ext_text, size_t ext_len,
- const char *text, size_t len)
-{
- struct console *con;
-
- trace_console_rcuidle(text, len);
-
- if (!console_drivers)
- return;
-
- for_each_console(con) {
- if (exclusive_console && con != exclusive_console)
- continue;
- if (!(con->flags & CON_ENABLED))
- continue;
- if (!con->write)
- continue;
- if (!cpu_online(smp_processor_id()) &&
- !(con->flags & CON_ANYTIME))
- continue;
- if (con->flags & CON_EXTENDED)
- con->write(con, ext_text, ext_len);
- else
- con->write(con, text, len);
- }
-}
-
int printk_delay_msec __read_mostly;
-static inline void printk_delay(void)
+static inline void printk_delay(int level)
{
+ boot_delay_msec(level);
+
if (unlikely(printk_delay_msec)) {
int m = printk_delay_msec;
@@ -1903,236 +1723,405 @@
}
}
-/*
- * Continuation lines are buffered, and not committed to the record buffer
- * until the line is complete, or a race forces it. The line fragments
- * though, are printed immediately to the consoles to ensure everything has
- * reached the console in case of a kernel crash.
- */
-static struct cont {
- char buf[LOG_LINE_MAX];
- size_t len; /* length == 0 means unused buffer */
- struct task_struct *owner; /* task of first print*/
- u64 ts_nsec; /* time of first print */
- u8 level; /* log level of first message */
- u8 facility; /* log facility of first message */
- enum log_flags flags; /* prefix, newline flags */
-} cont;
-
-static void cont_flush(void)
+static bool kernel_sync_mode(void)
{
- if (cont.len == 0)
- return;
-
- log_store(cont.facility, cont.level, cont.flags, cont.ts_nsec,
- NULL, 0, cont.buf, cont.len);
- cont.len = 0;
+ return (oops_in_progress || sync_mode);
}
-static bool cont_add(int facility, int level, enum log_flags flags, const char *text, size_t len)
+static bool console_can_sync(struct console *con)
{
- /*
- * If ext consoles are present, flush and skip in-kernel
- * continuation. See nr_ext_console_drivers definition. Also, if
- * the line gets too long, split it up in separate records.
- */
- if (nr_ext_console_drivers || cont.len + len > sizeof(cont.buf)) {
- cont_flush();
+ if (!(con->flags & CON_ENABLED))
return false;
- }
+ if (con->write_atomic && kernel_sync_mode())
+ return true;
+ if (con->write_atomic && (con->flags & CON_HANDOVER) && !con->thread)
+ return true;
+ if (con->write && (con->flags & CON_BOOT) && !con->thread)
+ return true;
+ return false;
+}
- if (!cont.len) {
- cont.facility = facility;
- cont.level = level;
- cont.owner = current;
- cont.ts_nsec = get_local_clock();
- cont.flags = flags;
- }
-
- memcpy(cont.buf + cont.len, text, len);
- cont.len += len;
-
- // The original flags come from the first line,
- // but later continuations can add a newline.
- if (flags & LOG_NEWLINE) {
- cont.flags |= LOG_NEWLINE;
- cont_flush();
- }
-
- if (cont.len > (sizeof(cont.buf) * 80) / 100)
- cont_flush();
+static bool call_sync_console_driver(struct console *con, const char *text, size_t text_len)
+{
+ if (!(con->flags & CON_ENABLED))
+ return false;
+ if (con->write_atomic && kernel_sync_mode())
+ con->write_atomic(con, text, text_len);
+ else if (con->write_atomic && (con->flags & CON_HANDOVER) && !con->thread)
+ con->write_atomic(con, text, text_len);
+ else if (con->write && (con->flags & CON_BOOT) && !con->thread)
+ con->write(con, text, text_len);
+ else
+ return false;
return true;
}
-static size_t log_output(int facility, int level, enum log_flags lflags, const char *dict, size_t dictlen, char *text, size_t text_len)
+static bool have_atomic_console(void)
{
- /*
- * If an earlier line was buffered, and we're a continuation
- * write from the same process, try to add it to the buffer.
- */
- if (cont.len) {
- if (cont.owner == current && (lflags & LOG_CONT)) {
- if (cont_add(facility, level, lflags, text, text_len))
- return text_len;
- }
- /* Otherwise, make sure it's flushed */
- cont_flush();
+ struct console *con;
+
+ for_each_console(con) {
+ if (!(con->flags & CON_ENABLED))
+ continue;
+ if (con->write_atomic)
+ return true;
}
-
- /* Skip empty continuation lines that couldn't be added - they just flush */
- if (!text_len && (lflags & LOG_CONT))
- return 0;
-
- /* If it doesn't end in a newline, try to buffer the current line */
- if (!(lflags & LOG_NEWLINE)) {
- if (cont_add(facility, level, lflags, text, text_len))
- return text_len;
- }
-
- /* Store it in the record log */
- return log_store(facility, level, lflags, 0, dict, dictlen, text, text_len);
+ return false;
}
-/* Must be called under logbuf_lock. */
-int vprintk_store(int facility, int level,
- const char *dict, size_t dictlen,
- const char *fmt, va_list args)
+static bool print_sync(struct console *con, u64 *seq)
{
- static char textbuf[LOG_LINE_MAX];
- char *text = textbuf;
+ struct printk_info info;
+ struct printk_record r;
size_t text_len;
- enum log_flags lflags = 0;
- /*
- * The printf needs to come first; we need the syslog
- * prefix which might be passed-in as a parameter.
- */
- text_len = vscnprintf(text, sizeof(textbuf), fmt, args);
+ prb_rec_init_rd(&r, &info, &con->sync_buf[0], sizeof(con->sync_buf));
- /* mark and strip a trailing newline */
- if (text_len && text[text_len-1] == '\n') {
- text_len--;
- lflags |= LOG_NEWLINE;
+ if (!prb_read_valid(prb, *seq, &r))
+ return false;
+
+ text_len = record_print_text(&r, console_msg_format & MSG_FORMAT_SYSLOG, printk_time);
+
+ if (!call_sync_console_driver(con, &con->sync_buf[0], text_len))
+ return false;
+
+ *seq = r.info->seq;
+
+ touch_softlockup_watchdog_sync();
+ clocksource_touch_watchdog();
+ rcu_cpu_stall_reset();
+ touch_nmi_watchdog();
+
+ if (text_len)
+ printk_delay(r.info->level);
+
+ return true;
+}
+
+static void print_sync_until(struct console *con, u64 seq)
+{
+ unsigned int flags;
+ u64 printk_seq;
+
+ console_atomic_lock(&flags);
+ for (;;) {
+ printk_seq = atomic64_read(&con->printk_seq);
+ if (printk_seq >= seq)
+ break;
+ if (!print_sync(con, &printk_seq))
+ break;
+ atomic64_set(&con->printk_seq, printk_seq + 1);
+ }
+ console_atomic_unlock(flags);
+}
+
+#ifdef CONFIG_PRINTK_NMI
+#define NUM_RECURSION_CTX 2
+#else
+#define NUM_RECURSION_CTX 1
+#endif
+
+struct printk_recursion {
+ char count[NUM_RECURSION_CTX];
+};
+
+static DEFINE_PER_CPU(struct printk_recursion, percpu_printk_recursion);
+static char printk_recursion_count[NUM_RECURSION_CTX];
+
+static char *printk_recursion_counter(void)
+{
+ struct printk_recursion *rec;
+ char *count;
+
+ if (!printk_percpu_data_ready()) {
+ count = &printk_recursion_count[0];
+ } else {
+ rec = this_cpu_ptr(&percpu_printk_recursion);
+
+ count = &rec->count[0];
}
- /* strip kernel syslog prefix and extract log level or control flags */
+#ifdef CONFIG_PRINTK_NMI
+ if (in_nmi())
+ count++;
+#endif
+
+ return count;
+}
+
+static bool printk_enter_irqsave(unsigned long *flags)
+{
+ char *count;
+
+ local_irq_save(*flags);
+ count = printk_recursion_counter();
+ /* Only 1 level of recursion allowed. */
+ if (*count > 1) {
+ local_irq_restore(*flags);
+ return false;
+ }
+ (*count)++;
+
+ return true;
+}
+
+static void printk_exit_irqrestore(unsigned long flags)
+{
+ char *count;
+
+ count = printk_recursion_counter();
+ (*count)--;
+ local_irq_restore(flags);
+}
+
+static inline u32 printk_caller_id(void)
+{
+ return in_task() ? task_pid_nr(current) :
+ 0x80000000 + raw_smp_processor_id();
+}
+
+/**
+ * parse_prefix - Parse level and control flags.
+ *
+ * @text: The terminated text message.
+ * @level: A pointer to the current level value, will be updated.
+ * @lflags: A pointer to the current log flags, will be updated.
+ *
+ * @level may be NULL if the caller is not interested in the parsed value.
+ * Otherwise the variable pointed to by @level must be set to
+ * LOGLEVEL_DEFAULT in order to be updated with the parsed value.
+ *
+ * @lflags may be NULL if the caller is not interested in the parsed value.
+ * Otherwise the variable pointed to by @lflags will be OR'd with the parsed
+ * value.
+ *
+ * Return: The length of the parsed level and control flags.
+ */
+static u16 parse_prefix(char *text, int *level, enum log_flags *lflags)
+{
+ u16 prefix_len = 0;
+ int kern_level;
+
+ while (*text) {
+ kern_level = printk_get_level(text);
+ if (!kern_level)
+ break;
+
+ switch (kern_level) {
+ case '0' ... '7':
+ if (level && *level == LOGLEVEL_DEFAULT)
+ *level = kern_level - '0';
+ break;
+ case 'c': /* KERN_CONT */
+ if (lflags)
+ *lflags |= LOG_CONT;
+ }
+
+ prefix_len += 2;
+ text += 2;
+ }
+
+ return prefix_len;
+}
+
+static u16 printk_sprint(char *text, u16 size, int facility, enum log_flags *lflags,
+ const char *fmt, va_list args)
+{
+ u16 text_len;
+
+ text_len = vscnprintf(text, size, fmt, args);
+
+ /* Mark and strip a trailing newline. */
+ if (text_len && text[text_len - 1] == '\n') {
+ text_len--;
+ *lflags |= LOG_NEWLINE;
+ }
+
+ /* Strip log level and control flags. */
if (facility == 0) {
- int kern_level;
+ u16 prefix_len;
- while ((kern_level = printk_get_level(text)) != 0) {
- switch (kern_level) {
- case '0' ... '7':
- if (level == LOGLEVEL_DEFAULT)
- level = kern_level - '0';
- /* fallthrough */
- case 'd': /* KERN_DEFAULT */
- lflags |= LOG_PREFIX;
- break;
- case 'c': /* KERN_CONT */
- lflags |= LOG_CONT;
- }
-
- text_len -= 2;
- text += 2;
+ prefix_len = parse_prefix(text, NULL, NULL);
+ if (prefix_len) {
+ text_len -= prefix_len;
+ memmove(text, text + prefix_len, text_len);
}
}
+
+ return text_len;
+}
+
+__printf(4, 0)
+static int vprintk_store(int facility, int level,
+ const struct dev_printk_info *dev_info,
+ const char *fmt, va_list args)
+{
+ const u32 caller_id = printk_caller_id();
+ struct prb_reserved_entry e;
+ enum log_flags lflags = 0;
+ bool final_commit = false;
+ struct printk_record r;
+ unsigned long irqflags;
+ u16 trunc_msg_len = 0;
+ char prefix_buf[8];
+ u16 reserve_size;
+ va_list args2;
+ u16 text_len;
+ int ret = 0;
+ u64 ts_nsec;
+ u64 seq;
+
+ /*
+ * Since the duration of printk() can vary depending on the message
+ * and state of the ringbuffer, grab the timestamp now so that it is
+ * close to the call of printk(). This provides a more deterministic
+ * timestamp with respect to the caller.
+ */
+ ts_nsec = local_clock();
+
+ if (!printk_enter_irqsave(&irqflags))
+ return 0;
+
+ /*
+ * The sprintf needs to come first since the syslog prefix might be
+ * passed in as a parameter. An extra byte must be reserved so that
+ * later the vscnprintf() into the reserved buffer has room for the
+ * terminating '\0', which is not counted by vsnprintf().
+ */
+ va_copy(args2, args);
+ reserve_size = vsnprintf(&prefix_buf[0], sizeof(prefix_buf), fmt, args2) + 1;
+ va_end(args2);
+
+ if (reserve_size > LOG_LINE_MAX)
+ reserve_size = LOG_LINE_MAX;
+
+ /* Extract log level or control flags. */
+ if (facility == 0)
+ parse_prefix(&prefix_buf[0], &level, &lflags);
if (level == LOGLEVEL_DEFAULT)
level = default_message_loglevel;
- if (dict)
- lflags |= LOG_PREFIX|LOG_NEWLINE;
+ if (dev_info)
+ lflags |= LOG_NEWLINE;
- return log_output(facility, level, lflags,
- dict, dictlen, text, text_len);
+ if (lflags & LOG_CONT) {
+ prb_rec_init_wr(&r, reserve_size);
+ if (prb_reserve_in_last(&e, prb, &r, caller_id, LOG_LINE_MAX)) {
+ seq = r.info->seq;
+ text_len = printk_sprint(&r.text_buf[r.info->text_len], reserve_size,
+ facility, &lflags, fmt, args);
+ r.info->text_len += text_len;
+
+ if (lflags & LOG_NEWLINE) {
+ r.info->flags |= LOG_NEWLINE;
+ prb_final_commit(&e);
+ final_commit = true;
+ } else {
+ prb_commit(&e);
+ }
+
+ ret = text_len;
+ goto out;
+ }
+ }
+
+ /*
+ * Explicitly initialize the record before every prb_reserve() call.
+ * prb_reserve_in_last() and prb_reserve() purposely invalidate the
+ * structure when they fail.
+ */
+ prb_rec_init_wr(&r, reserve_size);
+ if (!prb_reserve(&e, prb, &r)) {
+ /* truncate the message if it is too long for empty buffer */
+ truncate_msg(&reserve_size, &trunc_msg_len);
+
+ prb_rec_init_wr(&r, reserve_size + trunc_msg_len);
+ if (!prb_reserve(&e, prb, &r))
+ goto out;
+ }
+
+ seq = r.info->seq;
+
+ /* fill message */
+ text_len = printk_sprint(&r.text_buf[0], reserve_size, facility, &lflags, fmt, args);
+ if (trunc_msg_len)
+ memcpy(&r.text_buf[text_len], trunc_msg, trunc_msg_len);
+ r.info->text_len = text_len + trunc_msg_len;
+ r.info->facility = facility;
+ r.info->level = level & 7;
+ r.info->flags = lflags & 0x1f;
+ r.info->ts_nsec = ts_nsec;
+ r.info->caller_id = caller_id;
+ if (dev_info)
+ memcpy(&r.info->dev_info, dev_info, sizeof(r.info->dev_info));
+
+ /* A message without a trailing newline can be continued. */
+ if (!(lflags & LOG_NEWLINE)) {
+ prb_commit(&e);
+ } else {
+ prb_final_commit(&e);
+ final_commit = true;
+ }
+
+ ret = text_len + trunc_msg_len;
+out:
+ /* only the kernel may perform synchronous printing */
+ if (facility == 0 && final_commit) {
+ struct console *con;
+
+ for_each_console(con) {
+ if (console_can_sync(con))
+ print_sync_until(con, seq + 1);
+ }
+ }
+
+ printk_exit_irqrestore(irqflags);
+ return ret;
}
asmlinkage int vprintk_emit(int facility, int level,
- const char *dict, size_t dictlen,
+ const struct dev_printk_info *dev_info,
const char *fmt, va_list args)
{
int printed_len;
- bool in_sched = false, pending_output;
- unsigned long flags;
- u64 curr_log_seq;
- if (level == LOGLEVEL_SCHED) {
+ /* Suppress unimportant messages after panic happens */
+ if (unlikely(suppress_printk))
+ return 0;
+
+ if (level == LOGLEVEL_SCHED)
level = LOGLEVEL_DEFAULT;
- in_sched = true;
- }
- boot_delay_msec(level);
- printk_delay();
+ printed_len = vprintk_store(facility, level, dev_info, fmt, args);
- /* This stops the holder of console_sem just where we want him */
- logbuf_lock_irqsave(flags);
- curr_log_seq = log_next_seq;
- printed_len = vprintk_store(facility, level, dict, dictlen, fmt, args);
- pending_output = (curr_log_seq != log_next_seq);
- logbuf_unlock_irqrestore(flags);
-
- /* If called from the scheduler, we can not call up(). */
- if (!in_sched && pending_output) {
- /*
- * Disable preemption to avoid being preempted while holding
- * console_sem which would prevent anyone from printing to
- * console
- */
- preempt_disable();
- /*
- * Try to acquire and then immediately release the console
- * semaphore. The release will print out buffers and wake up
- * /dev/kmsg and syslog() users.
- */
- if (console_trylock_spinning())
- console_unlock();
- preempt_enable();
- }
-
- if (pending_output)
- wake_up_klogd();
+ wake_up_klogd();
return printed_len;
}
EXPORT_SYMBOL(vprintk_emit);
+
+__printf(1, 0)
+static int vprintk_default(const char *fmt, va_list args)
+{
+ return vprintk_emit(0, LOGLEVEL_DEFAULT, NULL, fmt, args);
+}
+__printf(1, 0)
+static int vprintk_func(const char *fmt, va_list args)
+{
+#ifdef CONFIG_KGDB_KDB
+ /* Allow to pass printk() to kdb but avoid a recursion. */
+ if (unlikely(kdb_trap_printk && kdb_printf_cpu < 0))
+ return vkdb_printf(KDB_MSGSRC_PRINTK, fmt, args);
+#endif
+ return vprintk_default(fmt, args);
+}
asmlinkage int vprintk(const char *fmt, va_list args)
{
return vprintk_func(fmt, args);
}
EXPORT_SYMBOL(vprintk);
-
-asmlinkage int printk_emit(int facility, int level,
- const char *dict, size_t dictlen,
- const char *fmt, ...)
-{
- va_list args;
- int r;
-
- va_start(args, fmt);
- r = vprintk_emit(facility, level, dict, dictlen, fmt, args);
- va_end(args);
-
- return r;
-}
-EXPORT_SYMBOL(printk_emit);
-
-int vprintk_default(const char *fmt, va_list args)
-{
- int r;
-
-#ifdef CONFIG_KGDB_KDB
- /* Allow to pass printk() to kdb but avoid a recursion. */
- if (unlikely(kdb_trap_printk && kdb_printf_cpu < 0)) {
- r = vkdb_printf(KDB_MSGSRC_PRINTK, fmt, args);
- return r;
- }
-#endif
- r = vprintk_emit(0, LOGLEVEL_DEFAULT, NULL, 0, fmt, args);
-
- return r;
-}
-EXPORT_SYMBOL_GPL(vprintk_default);
/**
* printk - print a kernel message
@@ -2168,36 +2157,162 @@
}
EXPORT_SYMBOL(printk);
+static int printk_kthread_func(void *data)
+{
+ struct console *con = data;
+ unsigned long dropped = 0;
+ char *dropped_text = NULL;
+ struct printk_info info;
+ struct printk_record r;
+ char *ext_text = NULL;
+ size_t dropped_len;
+ int ret = -ENOMEM;
+ char *text = NULL;
+ char *write_text;
+ u64 printk_seq;
+ size_t len;
+ int error;
+ u64 seq;
+
+ if (con->flags & CON_EXTENDED) {
+ ext_text = kmalloc(CONSOLE_EXT_LOG_MAX, GFP_KERNEL);
+ if (!ext_text)
+ goto out;
+ }
+ text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL);
+ dropped_text = kmalloc(64, GFP_KERNEL);
+ if (!text || !dropped_text)
+ goto out;
+
+ if (con->flags & CON_EXTENDED)
+ write_text = ext_text;
+ else
+ write_text = text;
+
+ seq = atomic64_read(&con->printk_seq);
+
+ prb_rec_init_rd(&r, &info, text, LOG_LINE_MAX + PREFIX_MAX);
+
+ for (;;) {
+ error = wait_event_interruptible(log_wait,
+ prb_read_valid(prb, seq, &r) || kthread_should_stop());
+
+ if (kthread_should_stop())
+ break;
+
+ if (error)
+ continue;
+
+ if (seq != r.info->seq) {
+ dropped += r.info->seq - seq;
+ seq = r.info->seq;
+ }
+
+ seq++;
+
+ if (!(con->flags & CON_ENABLED))
+ continue;
+
+ if (suppress_message_printing(r.info->level))
+ continue;
+
+ if (con->flags & CON_EXTENDED) {
+ len = info_print_ext_header(ext_text,
+ CONSOLE_EXT_LOG_MAX,
+ r.info);
+ len += msg_print_ext_body(ext_text + len,
+ CONSOLE_EXT_LOG_MAX - len,
+ &r.text_buf[0], r.info->text_len,
+ &r.info->dev_info);
+ } else {
+ len = record_print_text(&r,
+ console_msg_format & MSG_FORMAT_SYSLOG,
+ printk_time);
+ }
+
+ printk_seq = atomic64_read(&con->printk_seq);
+
+ console_lock();
+ console_may_schedule = 0;
+
+ if (kernel_sync_mode() && con->write_atomic) {
+ console_unlock();
+ break;
+ }
+
+ if (!(con->flags & CON_EXTENDED) && dropped) {
+ dropped_len = snprintf(dropped_text, 64,
+ "** %lu printk messages dropped **\n",
+ dropped);
+ dropped = 0;
+
+ con->write(con, dropped_text, dropped_len);
+ printk_delay(r.info->level);
+ }
+
+ con->write(con, write_text, len);
+ if (len)
+ printk_delay(r.info->level);
+
+ atomic64_cmpxchg_relaxed(&con->printk_seq, printk_seq, seq);
+
+ console_unlock();
+ }
+out:
+ kfree(dropped_text);
+ kfree(text);
+ kfree(ext_text);
+ pr_info("%sconsole [%s%d]: printing thread stopped\n",
+ (con->flags & CON_BOOT) ? "boot" : "",
+ con->name, con->index);
+ return ret;
+}
+
+/* Must be called within console_lock(). */
+static void start_printk_kthread(struct console *con)
+{
+ /* No need to start a printing thread if the console cannot print. */
+ if (!con->write)
+ return;
+
+ con->thread = kthread_run(printk_kthread_func, con,
+ "pr/%s%d", con->name, con->index);
+ if (IS_ERR(con->thread)) {
+ pr_err("%sconsole [%s%d]: unable to start printing thread\n",
+ (con->flags & CON_BOOT) ? "boot" : "",
+ con->name, con->index);
+ return;
+ }
+ pr_info("%sconsole [%s%d]: printing thread started\n",
+ (con->flags & CON_BOOT) ? "boot" : "",
+ con->name, con->index);
+}
+
+/* protected by console_lock */
+static bool kthreads_started;
+
+/* Must be called within console_lock(). */
+static void console_try_thread(struct console *con)
+{
+ if (kthreads_started) {
+ start_printk_kthread(con);
+ return;
+ }
+
+ /*
+ * The printing threads have not been started yet. If this console
+ * can print synchronously, print all unprinted messages.
+ */
+ if (console_can_sync(con))
+ print_sync_until(con, prb_next_seq(prb));
+}
+
#else /* CONFIG_PRINTK */
-#define LOG_LINE_MAX 0
-#define PREFIX_MAX 0
+#define prb_first_valid_seq(rb) 0
+#define prb_next_seq(rb) 0
-static u64 syslog_seq;
-static u32 syslog_idx;
-static u64 console_seq;
-static u32 console_idx;
-static u64 exclusive_console_stop_seq;
-static u64 log_first_seq;
-static u32 log_first_idx;
-static u64 log_next_seq;
-static char *log_text(const struct printk_log *msg) { return NULL; }
-static char *log_dict(const struct printk_log *msg) { return NULL; }
-static struct printk_log *log_from_idx(u32 idx) { return NULL; }
-static u32 log_next(u32 idx) { return 0; }
-static ssize_t msg_print_ext_header(char *buf, size_t size,
- struct printk_log *msg,
- u64 seq) { return 0; }
-static ssize_t msg_print_ext_body(char *buf, size_t size,
- char *dict, size_t dict_len,
- char *text, size_t text_len) { return 0; }
-static void console_lock_spinning_enable(void) { }
-static int console_lock_spinning_disable_and_check(void) { return 0; }
-static void call_console_drivers(const char *ext_text, size_t ext_len,
- const char *text, size_t len) {}
-static size_t msg_print_text(const struct printk_log *msg,
- bool syslog, char *buf, size_t size) { return 0; }
-static bool suppress_message_printing(int level) { return false; }
+#define console_try_thread(con)
#endif /* CONFIG_PRINTK */
@@ -2222,7 +2337,7 @@
#endif
static int __add_preferred_console(char *name, int idx, char *options,
- char *brl_options)
+ char *brl_options, bool user_specified)
{
struct console_cmdline *c;
int i;
@@ -2237,6 +2352,8 @@
if (strcmp(c->name, name) == 0 && c->index == idx) {
if (!brl_options)
preferred_console = i;
+ if (user_specified)
+ c->user_specified = true;
return 0;
}
}
@@ -2246,6 +2363,7 @@
preferred_console = i;
strlcpy(c->name, name, sizeof(c->name));
c->options = options;
+ c->user_specified = user_specified;
braille_set_options(c, brl_options);
c->index = idx;
@@ -2278,7 +2396,7 @@
* for exacly this purpose.
*/
if (str[0] == 0 || strcmp(str, "null") == 0) {
- __add_preferred_console("ttynull", 0, NULL, NULL);
+ __add_preferred_console("ttynull", 0, NULL, NULL, true);
return 1;
}
@@ -2310,7 +2428,7 @@
idx = simple_strtoul(s, NULL, 10);
*s = 0;
- __add_preferred_console(buf, idx, options, brl_options);
+ __add_preferred_console(buf, idx, options, brl_options, true);
console_set_on_cmdline = 1;
return 1;
}
@@ -2331,7 +2449,7 @@
*/
int add_preferred_console(char *name, int idx, char *options)
{
- return __add_preferred_console(name, idx, options, NULL);
+ return __add_preferred_console(name, idx, options, NULL, false);
}
bool console_suspend_enabled = true;
@@ -2383,6 +2501,12 @@
*/
static int console_cpu_notify(unsigned int cpu)
{
+ int flag = 0;
+
+ trace_android_vh_printk_hotplug(&flag);
+ if (flag)
+ return 0;
+
if (!cpuhp_tasks_frozen) {
/* If trylock fails, someone else is doing the printing */
if (console_trylock())
@@ -2439,34 +2563,6 @@
}
EXPORT_SYMBOL(is_console_locked);
-/*
- * Check if we have any console that is capable of printing while cpu is
- * booting or shutting down. Requires console_sem.
- */
-static int have_callable_console(void)
-{
- struct console *con;
-
- for_each_console(con)
- if ((con->flags & CON_ENABLED) &&
- (con->flags & CON_ANYTIME))
- return 1;
-
- return 0;
-}
-
-/*
- * Can we actually use the console at this time on this cpu?
- *
- * Console drivers may assume that per-cpu resources have been allocated. So
- * unless they're explicitly marked as being able to cope (CON_ANYTIME) don't
- * call them until this CPU is officially up.
- */
-static inline int can_use_console(void)
-{
- return cpu_online(raw_smp_processor_id()) || have_callable_console();
-}
-
/**
* console_unlock - unlock the console system
*
@@ -2483,148 +2579,14 @@
*/
void console_unlock(void)
{
- static char ext_text[CONSOLE_EXT_LOG_MAX];
- static char text[LOG_LINE_MAX + PREFIX_MAX];
- unsigned long flags;
- bool do_cond_resched, retry;
-
if (console_suspended) {
up_console_sem();
return;
}
- /*
- * Console drivers are called with interrupts disabled, so
- * @console_may_schedule should be cleared before; however, we may
- * end up dumping a lot of lines, for example, if called from
- * console registration path, and should invoke cond_resched()
- * between lines if allowable. Not doing so can cause a very long
- * scheduling stall on a slow console leading to RCU stall and
- * softlockup warnings which exacerbate the issue with more
- * messages practically incapacitating the system.
- *
- * console_trylock() is not able to detect the preemptive
- * context reliably. Therefore the value must be stored before
- * and cleared after the the "again" goto label.
- */
- do_cond_resched = console_may_schedule;
-again:
- console_may_schedule = 0;
-
- /*
- * We released the console_sem lock, so we need to recheck if
- * cpu is online and (if not) is there at least one CON_ANYTIME
- * console.
- */
- if (!can_use_console()) {
- console_locked = 0;
- up_console_sem();
- return;
- }
-
- for (;;) {
- struct printk_log *msg;
- size_t ext_len = 0;
- size_t len;
-
- printk_safe_enter_irqsave(flags);
- raw_spin_lock(&logbuf_lock);
- if (console_seq < log_first_seq) {
- len = sprintf(text,
- "** %llu printk messages dropped **\n",
- log_first_seq - console_seq);
-
- /* messages are gone, move to first one */
- console_seq = log_first_seq;
- console_idx = log_first_idx;
- } else {
- len = 0;
- }
-skip:
- if (console_seq == log_next_seq)
- break;
-
- msg = log_from_idx(console_idx);
- if (suppress_message_printing(msg->level)) {
- /*
- * Skip record we have buffered and already printed
- * directly to the console when we received it, and
- * record that has level above the console loglevel.
- */
- console_idx = log_next(console_idx);
- console_seq++;
- goto skip;
- }
-
- /* Output to all consoles once old messages replayed. */
- if (unlikely(exclusive_console &&
- console_seq >= exclusive_console_stop_seq)) {
- exclusive_console = NULL;
- }
-
- len += msg_print_text(msg,
- console_msg_format & MSG_FORMAT_SYSLOG,
- text + len,
- sizeof(text) - len);
- if (nr_ext_console_drivers) {
- ext_len = msg_print_ext_header(ext_text,
- sizeof(ext_text),
- msg, console_seq);
- ext_len += msg_print_ext_body(ext_text + ext_len,
- sizeof(ext_text) - ext_len,
- log_dict(msg), msg->dict_len,
- log_text(msg), msg->text_len);
- }
- console_idx = log_next(console_idx);
- console_seq++;
- raw_spin_unlock(&logbuf_lock);
-
- /*
- * While actively printing out messages, if another printk()
- * were to occur on another CPU, it may wait for this one to
- * finish. This task can not be preempted if there is a
- * waiter waiting to take over.
- */
- console_lock_spinning_enable();
-
- stop_critical_timings(); /* don't trace print latency */
-#ifdef CONFIG_PSTORE_CONSOLE_FORCE
- call_console_drivers_level(msg->level, ext_text, ext_len, text, len);
-#else
- call_console_drivers(ext_text, ext_len, text, len);
-#endif
- start_critical_timings();
-
- if (console_lock_spinning_disable_and_check()) {
- printk_safe_exit_irqrestore(flags);
- return;
- }
-
- printk_safe_exit_irqrestore(flags);
-
- if (do_cond_resched)
- cond_resched();
- }
-
console_locked = 0;
- raw_spin_unlock(&logbuf_lock);
-
up_console_sem();
-
- /*
- * Someone could have filled up the buffer again, so re-check if there's
- * something to flush. In case we cannot trylock the console_sem again,
- * there's a new owner and the console_unlock() from them will do the
- * flush, no worries.
- */
- raw_spin_lock(&logbuf_lock);
- retry = console_seq != log_next_seq;
- raw_spin_unlock(&logbuf_lock);
- printk_safe_exit_irqrestore(flags);
-
- if (retry && console_trylock())
- goto again;
}
EXPORT_SYMBOL(console_unlock);
@@ -2668,20 +2630,26 @@
/**
* console_flush_on_panic - flush console content on panic
+ * @mode: flush all messages in buffer or just the pending ones
*
* Immediately output all pending messages no matter what.
*/
-void console_flush_on_panic(void)
+void console_flush_on_panic(enum con_flush_mode mode)
{
- /*
- * If someone else is holding the console lock, trylock will fail
- * and may_schedule may be set. Ignore and proceed to unlock so
- * that messages are flushed out. As this can be called from any
- * context and we don't want to get preempted while flushing,
- * ensure may_schedule is cleared.
- */
- console_trylock();
+ struct console *c;
+ u64 seq;
+
+ if (!console_trylock())
+ return;
+
console_may_schedule = 0;
+
+ if (mode == CONSOLE_REPLAY_ALL) {
+ seq = prb_first_valid_seq(prb);
+ for_each_console(c)
+ atomic64_set(&c->printk_seq, seq);
+ }
+
console_unlock();
}
@@ -2739,6 +2707,63 @@
early_param("keep_bootcon", keep_bootcon_setup);
/*
+ * This is called by register_console() to try to match
+ * the newly registered console with any of the ones selected
+ * by either the command line or add_preferred_console() and
+ * setup/enable it.
+ *
+ * Care need to be taken with consoles that are statically
+ * enabled such as netconsole
+ */
+static int try_enable_new_console(struct console *newcon, bool user_specified)
+{
+ struct console_cmdline *c;
+ int i, err;
+
+ for (i = 0, c = console_cmdline;
+ i < MAX_CMDLINECONSOLES && c->name[0];
+ i++, c++) {
+ if (c->user_specified != user_specified)
+ continue;
+ if (!newcon->match ||
+ newcon->match(newcon, c->name, c->index, c->options) != 0) {
+ /* default matching */
+ BUILD_BUG_ON(sizeof(c->name) != sizeof(newcon->name));
+ if (strcmp(c->name, newcon->name) != 0)
+ continue;
+ if (newcon->index >= 0 &&
+ newcon->index != c->index)
+ continue;
+ if (newcon->index < 0)
+ newcon->index = c->index;
+
+ if (_braille_register_console(newcon, c))
+ return 0;
+
+ if (newcon->setup &&
+ (err = newcon->setup(newcon, c->options)) != 0)
+ return err;
+ }
+ newcon->flags |= CON_ENABLED;
+ if (i == preferred_console) {
+ newcon->flags |= CON_CONSDEV;
+ has_preferred_console = true;
+ }
+ return 0;
+ }
+
+ /*
+ * Some consoles, such as pstore and netconsole, can be enabled even
+ * without matching. Accept the pre-enabled consoles only when match()
+ * and setup() had a chance to be called.
+ */
+ if (newcon->flags & CON_ENABLED && c->user_specified == user_specified)
+ return 0;
+
+ return -ENOENT;
+}
+
+/*
* The console driver calls this routine during kernel initialization
* to register the console printing procedure with printk() and to
* print any messages that were printed by the kernel before the
@@ -2759,25 +2784,20 @@
*/
void register_console(struct console *newcon)
{
- int i;
- unsigned long flags;
struct console *bcon = NULL;
- struct console_cmdline *c;
- static bool has_preferred;
+ int err;
- if (console_drivers)
- for_each_console(bcon)
- if (WARN(bcon == newcon,
- "console '%s%d' already registered\n",
- bcon->name, bcon->index))
- return;
+ for_each_console(bcon) {
+ if (WARN(bcon == newcon, "console '%s%d' already registered\n",
+ bcon->name, bcon->index))
+ return;
+ }
/*
* before we register a new CON_BOOT console, make sure we don't
* already have a valid console
*/
- if (console_drivers && newcon->flags & CON_BOOT) {
- /* find the last or real console */
+ if (newcon->flags & CON_BOOT) {
for_each_console(bcon) {
if (!(bcon->flags & CON_BOOT)) {
pr_info("Too late to register bootconsole %s%d\n",
@@ -2787,18 +2807,20 @@
}
}
+ newcon->thread = NULL;
+
if (console_drivers && console_drivers->flags & CON_BOOT)
bcon = console_drivers;
- if (!has_preferred || bcon || !console_drivers)
- has_preferred = preferred_console >= 0;
+ if (!has_preferred_console || bcon || !console_drivers)
+ has_preferred_console = preferred_console >= 0;
/*
* See if we want to use this console driver. If we
* didn't select a console we take the first one
* that registers here.
*/
- if (!has_preferred) {
+ if (!has_preferred_console) {
if (newcon->index < 0)
newcon->index = 0;
if (newcon->setup == NULL ||
@@ -2806,47 +2828,20 @@
newcon->flags |= CON_ENABLED;
if (newcon->device) {
newcon->flags |= CON_CONSDEV;
- has_preferred = true;
+ has_preferred_console = true;
}
}
}
- /*
- * See if this console matches one we selected on
- * the command line.
- */
- for (i = 0, c = console_cmdline;
- i < MAX_CMDLINECONSOLES && c->name[0];
- i++, c++) {
- if (!newcon->match ||
- newcon->match(newcon, c->name, c->index, c->options) != 0) {
- /* default matching */
- BUILD_BUG_ON(sizeof(c->name) != sizeof(newcon->name));
- if (strcmp(c->name, newcon->name) != 0)
- continue;
- if (newcon->index >= 0 &&
- newcon->index != c->index)
- continue;
- if (newcon->index < 0)
- newcon->index = c->index;
+ /* See if this console matches one we selected on the command line */
+ err = try_enable_new_console(newcon, true);
- if (_braille_register_console(newcon, c))
- return;
+ /* If not, try to match against the platform default(s) */
+ if (err == -ENOENT)
+ err = try_enable_new_console(newcon, false);
- if (newcon->setup &&
- newcon->setup(newcon, c->options) != 0)
- break;
- }
-
- newcon->flags |= CON_ENABLED;
- if (i == preferred_console) {
- newcon->flags |= CON_CONSDEV;
- has_preferred = true;
- }
- break;
- }
-
- if (!(newcon->flags & CON_ENABLED))
+ /* printk() messages are not printed to the Braille console. */
+ if (err || newcon->flags & CON_BRL)
return;
/*
@@ -2855,8 +2850,10 @@
* the real console are the same physical device, it's annoying to
* see the beginning boot messages twice
*/
- if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV))
+ if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) {
newcon->flags &= ~CON_PRINTBUFFER;
+ newcon->flags |= CON_HANDOVER;
+ }
/*
* Put this console in the list - keep the
@@ -2868,36 +2865,22 @@
console_drivers = newcon;
if (newcon->next)
newcon->next->flags &= ~CON_CONSDEV;
+ /* Ensure this flag is always set for the head of the list */
+ newcon->flags |= CON_CONSDEV;
} else {
newcon->next = console_drivers->next;
console_drivers->next = newcon;
}
if (newcon->flags & CON_EXTENDED)
- if (!nr_ext_console_drivers++)
- pr_info("printk: continuation disabled due to ext consoles, expect more fragments in /dev/kmsg\n");
+ nr_ext_console_drivers++;
- if (newcon->flags & CON_PRINTBUFFER) {
- /*
- * console_unlock(); will print out the buffered messages
- * for us.
- */
- logbuf_lock_irqsave(flags);
- /*
- * We're about to replay the log buffer. Only do this to the
- * just-registered console to avoid excessive message spam to
- * the already-registered consoles.
- *
- * Set exclusive_console with disabled interrupts to reduce
- * race window with eventual console_flush_on_panic() that
- * ignores console_lock.
- */
- exclusive_console = newcon;
- exclusive_console_stop_seq = console_seq;
- console_seq = syslog_seq;
- console_idx = syslog_idx;
- logbuf_unlock_irqrestore(flags);
- }
+ if (newcon->flags & CON_PRINTBUFFER)
+ atomic64_set(&newcon->printk_seq, 0);
+ else
+ atomic64_set(&newcon->printk_seq, prb_next_seq(prb));
+
+ console_try_thread(newcon);
console_unlock();
console_sysfs_notify();
@@ -2926,7 +2909,7 @@
int unregister_console(struct console *console)
{
- struct console *a, *b;
+ struct console *con;
int res;
pr_info("%sconsole [%s%d] disabled\n",
@@ -2934,26 +2917,30 @@
console->name, console->index);
res = _braille_unregister_console(console);
- if (res)
+ if (res < 0)
return res;
+ if (res > 0)
+ return 0;
- res = 1;
+ res = -ENODEV;
console_lock();
if (console_drivers == console) {
console_drivers=console->next;
res = 0;
- } else if (console_drivers) {
- for (a=console_drivers->next, b=console_drivers ;
- a; b=a, a=b->next) {
- if (a == console) {
- b->next = a->next;
+ } else {
+ for_each_console(con) {
+ if (con->next == console) {
+ con->next = console->next;
res = 0;
break;
}
}
}
- if (!res && (console->flags & CON_EXTENDED))
+ if (res)
+ goto out_disable_unlock;
+
+ if (console->flags & CON_EXTENDED)
nr_ext_console_drivers--;
/*
@@ -2966,6 +2953,19 @@
console->flags &= ~CON_ENABLED;
console_unlock();
console_sysfs_notify();
+
+ if (console->thread && !IS_ERR(console->thread))
+ kthread_stop(console->thread);
+
+ if (console->exit)
+ res = console->exit(console);
+
+ return res;
+
+out_disable_unlock:
+ console->flags &= ~CON_ENABLED;
+ console_unlock();
+
return res;
}
EXPORT_SYMBOL(unregister_console);
@@ -3039,6 +3039,15 @@
unregister_console(con);
}
}
+
+#ifdef CONFIG_PRINTK
+ console_lock();
+ for_each_console(con)
+ start_printk_kthread(con);
+ kthreads_started = true;
+ console_unlock();
+#endif
+
ret = cpuhp_setup_state_nocalls(CPUHP_PRINTK_DEAD, "printk:dead", NULL,
console_cpu_notify);
WARN_ON(ret < 0);
@@ -3054,7 +3063,6 @@
* Delayed printk version, for scheduler-internal messages:
*/
#define PRINTK_PENDING_WAKEUP 0x01
-#define PRINTK_PENDING_OUTPUT 0x02
static DEFINE_PER_CPU(int, printk_pending);
@@ -3062,19 +3070,13 @@
{
int pending = __this_cpu_xchg(printk_pending, 0);
- if (pending & PRINTK_PENDING_OUTPUT) {
- /* If trylock fails, someone else is doing the printing */
- if (console_trylock())
- console_unlock();
- }
-
if (pending & PRINTK_PENDING_WAKEUP)
- wake_up_interruptible(&log_wait);
+ wake_up_interruptible_all(&log_wait);
}
static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) = {
.func = wake_up_klogd_work_func,
- .flags = IRQ_WORK_LAZY,
+ .flags = ATOMIC_INIT(IRQ_WORK_LAZY),
};
void wake_up_klogd(void)
@@ -3090,25 +3092,10 @@
preempt_enable();
}
-void defer_console_output(void)
+__printf(1, 0)
+static int vprintk_deferred(const char *fmt, va_list args)
{
- if (!printk_percpu_data_ready())
- return;
-
- preempt_disable();
- __this_cpu_or(printk_pending, PRINTK_PENDING_OUTPUT);
- irq_work_queue(this_cpu_ptr(&wake_up_klogd_work));
- preempt_enable();
-}
-
-int vprintk_deferred(const char *fmt, va_list args)
-{
- int r;
-
- r = vprintk_emit(0, LOGLEVEL_SCHED, NULL, 0, fmt, args);
- defer_console_output();
-
- return r;
+ return vprintk_emit(0, LOGLEVEL_DEFAULT, NULL, fmt, args);
}
int printk_deferred(const char *fmt, ...)
@@ -3122,6 +3109,7 @@
return r;
}
+EXPORT_SYMBOL_GPL(printk_deferred);
/*
* printk rate limiting, lifted from the networking subsystem.
@@ -3220,6 +3208,23 @@
static bool always_kmsg_dump;
module_param_named(always_kmsg_dump, always_kmsg_dump, bool, S_IRUGO | S_IWUSR);
+const char *kmsg_dump_reason_str(enum kmsg_dump_reason reason)
+{
+ switch (reason) {
+ case KMSG_DUMP_PANIC:
+ return "Panic";
+ case KMSG_DUMP_OOPS:
+ return "Oops";
+ case KMSG_DUMP_EMERG:
+ return "Emergency";
+ case KMSG_DUMP_SHUTDOWN:
+ return "Shutdown";
+ default:
+ return "Unknown";
+ }
+}
+EXPORT_SYMBOL_GPL(kmsg_dump_reason_str);
+
/**
* kmsg_dump - dump kernel log to kernel message dumpers.
* @reason: the reason (oops, panic etc) for dumping
@@ -3230,39 +3235,55 @@
*/
void kmsg_dump(enum kmsg_dump_reason reason)
{
+ struct kmsg_dumper_iter iter;
struct kmsg_dumper *dumper;
- unsigned long flags;
- if ((reason > KMSG_DUMP_OOPS) && !always_kmsg_dump)
- return;
+ if (!oops_in_progress) {
+ /*
+ * If atomic consoles are available, activate kernel sync mode
+ * to make sure any final messages are visible. The trailing
+ * printk message is important to flush any pending messages.
+ */
+ if (have_atomic_console()) {
+ sync_mode = true;
+ pr_info("enabled sync mode\n");
+ }
+
+ /*
+ * Give the printing threads time to flush, allowing up to
+ * 1s of no printing forward progress before giving up.
+ */
+ pr_flush(1000, true);
+ }
rcu_read_lock();
list_for_each_entry_rcu(dumper, &dump_list, list) {
- if (dumper->max_reason && reason > dumper->max_reason)
+ enum kmsg_dump_reason max_reason = dumper->max_reason;
+
+ /*
+ * If client has not provided a specific max_reason, default
+ * to KMSG_DUMP_OOPS, unless always_kmsg_dump was set.
+ */
+ if (max_reason == KMSG_DUMP_UNDEF) {
+ max_reason = always_kmsg_dump ? KMSG_DUMP_MAX :
+ KMSG_DUMP_OOPS;
+ }
+ if (reason > max_reason)
continue;
/* initialize iterator with data about the stored records */
- dumper->active = true;
-
- logbuf_lock_irqsave(flags);
- dumper->cur_seq = clear_seq;
- dumper->cur_idx = clear_idx;
- dumper->next_seq = log_next_seq;
- dumper->next_idx = log_next_idx;
- logbuf_unlock_irqrestore(flags);
+ iter.active = true;
+ kmsg_dump_rewind(&iter);
/* invoke dumper which will iterate over records */
- dumper->dump(dumper, reason);
-
- /* reset iterator */
- dumper->active = false;
+ dumper->dump(dumper, reason, &iter);
}
rcu_read_unlock();
}
/**
- * kmsg_dump_get_line_nolock - retrieve one kmsg log line (unlocked version)
- * @dumper: registered kmsg dumper
+ * kmsg_dump_get_line - retrieve one kmsg log line
+ * @iter: kmsg dumper iterator
* @syslog: include the "<4>" prefixes
* @line: buffer to copy the line to
* @size: maximum size of the buffer
@@ -3276,82 +3297,55 @@
*
* A return value of FALSE indicates that there are no more records to
* read.
- *
- * The function is similar to kmsg_dump_get_line(), but grabs no locks.
*/
-bool kmsg_dump_get_line_nolock(struct kmsg_dumper *dumper, bool syslog,
- char *line, size_t size, size_t *len)
+bool kmsg_dump_get_line(struct kmsg_dumper_iter *iter, bool syslog,
+ char *line, size_t size, size_t *len)
{
- struct printk_log *msg;
+ struct printk_info info;
+ unsigned int line_count;
+ struct printk_record r;
size_t l = 0;
bool ret = false;
- if (!dumper->active)
+ prb_rec_init_rd(&r, &info, line, size);
+
+ if (!iter->active)
goto out;
- if (dumper->cur_seq < log_first_seq) {
- /* messages are gone, move to first available one */
- dumper->cur_seq = log_first_seq;
- dumper->cur_idx = log_first_idx;
+ /* Read text or count text lines? */
+ if (line) {
+ if (!prb_read_valid(prb, iter->cur_seq, &r))
+ goto out;
+ l = record_print_text(&r, syslog, printk_time);
+ } else {
+ if (!prb_read_valid_info(prb, iter->cur_seq,
+ &info, &line_count)) {
+ goto out;
+ }
+ l = get_record_print_text_size(&info, line_count, syslog,
+ printk_time);
+
}
- /* last entry */
- if (dumper->cur_seq >= log_next_seq)
- goto out;
-
- msg = log_from_idx(dumper->cur_idx);
- l = msg_print_text(msg, syslog, line, size);
-
- dumper->cur_idx = log_next(dumper->cur_idx);
- dumper->cur_seq++;
+ iter->cur_seq = r.info->seq + 1;
ret = true;
out:
if (len)
*len = l;
return ret;
}
-
-/**
- * kmsg_dump_get_line - retrieve one kmsg log line
- * @dumper: registered kmsg dumper
- * @syslog: include the "<4>" prefixes
- * @line: buffer to copy the line to
- * @size: maximum size of the buffer
- * @len: length of line placed into buffer
- *
- * Start at the beginning of the kmsg buffer, with the oldest kmsg
- * record, and copy one record into the provided buffer.
- *
- * Consecutive calls will return the next available record moving
- * towards the end of the buffer with the youngest messages.
- *
- * A return value of FALSE indicates that there are no more records to
- * read.
- */
-bool kmsg_dump_get_line(struct kmsg_dumper *dumper, bool syslog,
- char *line, size_t size, size_t *len)
-{
- unsigned long flags;
- bool ret;
-
- logbuf_lock_irqsave(flags);
- ret = kmsg_dump_get_line_nolock(dumper, syslog, line, size, len);
- logbuf_unlock_irqrestore(flags);
-
- return ret;
-}
EXPORT_SYMBOL_GPL(kmsg_dump_get_line);
/**
* kmsg_dump_get_buffer - copy kmsg log lines
- * @dumper: registered kmsg dumper
+ * @iter: kmsg dumper iterator
* @syslog: include the "<4>" prefixes
* @buf: buffer to copy the line to
* @size: maximum size of the buffer
* @len: length of line placed into buffer
*
* Start at the end of the kmsg buffer and fill the provided buffer
- * with as many of the the *youngest* kmsg records that fit into it.
+ * with as many of the *youngest* kmsg records that fit into it.
* If the buffer is large enough, all available kmsg records will be
* copied with a single call.
*
@@ -3361,113 +3355,258 @@
* A return value of FALSE indicates that there are no more records to
* read.
*/
-bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog,
- char *buf, size_t size, size_t *len)
+bool kmsg_dump_get_buffer(struct kmsg_dumper_iter *iter, bool syslog,
+ char *buf, size_t size, size_t *len_out)
{
- unsigned long flags;
+ struct printk_info info;
+ struct printk_record r;
u64 seq;
- u32 idx;
u64 next_seq;
- u32 next_idx;
- size_t l = 0;
+ size_t len = 0;
bool ret = false;
+ bool time = printk_time;
- if (!dumper->active)
+ if (!iter->active || !buf || !size)
goto out;
- logbuf_lock_irqsave(flags);
- if (dumper->cur_seq < log_first_seq) {
- /* messages are gone, move to first available one */
- dumper->cur_seq = log_first_seq;
- dumper->cur_idx = log_first_idx;
+ if (prb_read_valid_info(prb, iter->cur_seq, &info, NULL)) {
+ if (info.seq != iter->cur_seq) {
+ /* messages are gone, move to first available one */
+ iter->cur_seq = info.seq;
+ }
}
/* last entry */
- if (dumper->cur_seq >= dumper->next_seq) {
- logbuf_unlock_irqrestore(flags);
+ if (iter->cur_seq >= iter->next_seq)
goto out;
- }
- /* calculate length of entire buffer */
- seq = dumper->cur_seq;
- idx = dumper->cur_idx;
- while (seq < dumper->next_seq) {
- struct printk_log *msg = log_from_idx(idx);
+ /*
+ * Find first record that fits, including all following records,
+ * into the user-provided buffer for this dump. Pass in size-1
+ * because this function (by way of record_print_text()) will
+ * not write more than size-1 bytes of text into @buf.
+ */
+ seq = find_first_fitting_seq(iter->cur_seq, iter->next_seq,
+ size - 1, syslog, time);
- l += msg_print_text(msg, true, NULL, 0);
- idx = log_next(idx);
- seq++;
- }
-
- /* move first record forward until length fits into the buffer */
- seq = dumper->cur_seq;
- idx = dumper->cur_idx;
- while (l >= size && seq < dumper->next_seq) {
- struct printk_log *msg = log_from_idx(idx);
-
- l -= msg_print_text(msg, true, NULL, 0);
- idx = log_next(idx);
- seq++;
- }
-
- /* last message in next interation */
+ /*
+ * Next kmsg_dump_get_buffer() invocation will dump block of
+ * older records stored right before this one.
+ */
next_seq = seq;
- next_idx = idx;
- l = 0;
- while (seq < dumper->next_seq) {
- struct printk_log *msg = log_from_idx(idx);
+ prb_rec_init_rd(&r, &info, buf, size);
- l += msg_print_text(msg, syslog, buf + l, size - l);
- idx = log_next(idx);
- seq++;
+ len = 0;
+ prb_for_each_record(seq, prb, seq, &r) {
+ if (r.info->seq >= iter->next_seq)
+ break;
+
+ len += record_print_text(&r, syslog, time);
+
+ /* Adjust record to store to remaining buffer space. */
+ prb_rec_init_rd(&r, &info, buf + len, size - len);
}
- dumper->next_seq = next_seq;
- dumper->next_idx = next_idx;
+ iter->next_seq = next_seq;
ret = true;
- logbuf_unlock_irqrestore(flags);
out:
- if (len)
- *len = l;
+ if (len_out)
+ *len_out = len;
return ret;
}
EXPORT_SYMBOL_GPL(kmsg_dump_get_buffer);
/**
- * kmsg_dump_rewind_nolock - reset the interator (unlocked version)
- * @dumper: registered kmsg dumper
- *
- * Reset the dumper's iterator so that kmsg_dump_get_line() and
- * kmsg_dump_get_buffer() can be called again and used multiple
- * times within the same dumper.dump() callback.
- *
- * The function is similar to kmsg_dump_rewind(), but grabs no locks.
- */
-void kmsg_dump_rewind_nolock(struct kmsg_dumper *dumper)
-{
- dumper->cur_seq = clear_seq;
- dumper->cur_idx = clear_idx;
- dumper->next_seq = log_next_seq;
- dumper->next_idx = log_next_idx;
-}
-
-/**
- * kmsg_dump_rewind - reset the interator
- * @dumper: registered kmsg dumper
+ * kmsg_dump_rewind - reset the iterator
+ * @iter: kmsg dumper iterator
*
* Reset the dumper's iterator so that kmsg_dump_get_line() and
* kmsg_dump_get_buffer() can be called again and used multiple
* times within the same dumper.dump() callback.
*/
-void kmsg_dump_rewind(struct kmsg_dumper *dumper)
+void kmsg_dump_rewind(struct kmsg_dumper_iter *iter)
{
- unsigned long flags;
-
- logbuf_lock_irqsave(flags);
- kmsg_dump_rewind_nolock(dumper);
- logbuf_unlock_irqrestore(flags);
+ iter->cur_seq = latched_seq_read_nolock(&clear_seq);
+ iter->next_seq = prb_next_seq(prb);
}
EXPORT_SYMBOL_GPL(kmsg_dump_rewind);
#endif
+
+struct prb_cpulock {
+ atomic_t owner;
+ unsigned long __percpu *irqflags;
+};
+
+#define DECLARE_STATIC_PRINTKRB_CPULOCK(name) \
+static DEFINE_PER_CPU(unsigned long, _##name##_percpu_irqflags); \
+static struct prb_cpulock name = { \
+ .owner = ATOMIC_INIT(-1), \
+ .irqflags = &_##name##_percpu_irqflags, \
+}
+
+static bool __prb_trylock(struct prb_cpulock *cpu_lock,
+ unsigned int *cpu_store)
+{
+ unsigned long *flags;
+ unsigned int cpu;
+
+ cpu = get_cpu();
+
+ *cpu_store = atomic_read(&cpu_lock->owner);
+ /* memory barrier to ensure the current lock owner is visible */
+ smp_rmb();
+ if (*cpu_store == -1) {
+ flags = per_cpu_ptr(cpu_lock->irqflags, cpu);
+ local_irq_save(*flags);
+ if (atomic_try_cmpxchg_acquire(&cpu_lock->owner,
+ cpu_store, cpu)) {
+ return true;
+ }
+ local_irq_restore(*flags);
+ } else if (*cpu_store == cpu) {
+ return true;
+ }
+
+ put_cpu();
+ return false;
+}
+
+/*
+ * prb_lock: Perform a processor-reentrant spin lock.
+ * @cpu_lock: A pointer to the lock object.
+ * @cpu_store: A "flags" pointer to store lock status information.
+ *
+ * If no processor has the lock, the calling processor takes the lock and
+ * becomes the owner. If the calling processor is already the owner of the
+ * lock, this function succeeds immediately. If lock is locked by another
+ * processor, this function spins until the calling processor becomes the
+ * owner.
+ *
+ * It is safe to call this function from any context and state.
+ */
+static void prb_lock(struct prb_cpulock *cpu_lock, unsigned int *cpu_store)
+{
+ for (;;) {
+ if (__prb_trylock(cpu_lock, cpu_store))
+ break;
+ cpu_relax();
+ }
+}
+
+/*
+ * prb_unlock: Perform a processor-reentrant spin unlock.
+ * @cpu_lock: A pointer to the lock object.
+ * @cpu_store: A "flags" object storing lock status information.
+ *
+ * Release the lock. The calling processor must be the owner of the lock.
+ *
+ * It is safe to call this function from any context and state.
+ */
+static void prb_unlock(struct prb_cpulock *cpu_lock, unsigned int cpu_store)
+{
+ unsigned long *flags;
+ unsigned int cpu;
+
+ cpu = atomic_read(&cpu_lock->owner);
+ atomic_set_release(&cpu_lock->owner, cpu_store);
+
+ if (cpu_store == -1) {
+ flags = per_cpu_ptr(cpu_lock->irqflags, cpu);
+ local_irq_restore(*flags);
+ }
+
+ put_cpu();
+}
+
+DECLARE_STATIC_PRINTKRB_CPULOCK(printk_cpulock);
+
+void console_atomic_lock(unsigned int *flags)
+{
+ prb_lock(&printk_cpulock, flags);
+}
+EXPORT_SYMBOL(console_atomic_lock);
+
+void console_atomic_unlock(unsigned int flags)
+{
+ prb_unlock(&printk_cpulock, flags);
+}
+EXPORT_SYMBOL(console_atomic_unlock);
+
+static void pr_msleep(bool may_sleep, int ms)
+{
+ if (may_sleep) {
+ msleep(ms);
+ } else {
+ while (ms--)
+ udelay(1000);
+ }
+}
+
+/**
+ * pr_flush() - Wait for printing threads to catch up.
+ *
+ * @timeout_ms: The maximum time (in ms) to wait.
+ * @reset_on_progress: Reset the timeout if forward progress is seen.
+ *
+ * A value of 0 for @timeout_ms means no waiting will occur. A value of -1
+ * represents infinite waiting.
+ *
+ * If @reset_on_progress is true, the timeout will be reset whenever any
+ * printer has been seen to make some forward progress.
+ *
+ * Context: Any context.
+ * Return: true if all enabled printers are caught up.
+ */
+bool pr_flush(int timeout_ms, bool reset_on_progress)
+{
+ int remaining = timeout_ms;
+ struct console *con;
+ u64 last_diff = 0;
+ bool may_sleep;
+ u64 printk_seq;
+ u64 diff;
+ u64 seq;
+
+ may_sleep = (preemptible() &&
+ !in_softirq() &&
+ system_state >= SYSTEM_RUNNING);
+
+ seq = prb_next_seq(prb);
+
+ for (;;) {
+ diff = 0;
+
+ for_each_console(con) {
+ if (!(con->flags & CON_ENABLED))
+ continue;
+ if (!con->write && !con->write_atomic)
+ continue;
+ printk_seq = atomic64_read(&con->printk_seq);
+ if (printk_seq < seq)
+ diff += seq - printk_seq;
+ }
+
+ if (diff != last_diff && reset_on_progress)
+ remaining = timeout_ms;
+
+ if (!diff || remaining == 0)
+ break;
+
+ if (remaining < 0) {
+ pr_msleep(may_sleep, 100);
+ } else if (remaining < 100) {
+ pr_msleep(may_sleep, remaining);
+ remaining = 0;
+ } else {
+ pr_msleep(may_sleep, 100);
+ remaining -= 100;
+ }
+
+ last_diff = diff;
+ }
+
+ return (diff == 0);
+}
+EXPORT_SYMBOL(pr_flush);
--
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