From 102a0743326a03cd1a1202ceda21e175b7d3575c Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Tue, 20 Feb 2024 01:20:52 +0000
Subject: [PATCH] add new system file
---
kernel/kernel/trace/ring_buffer.c | 1526 +++++++++++++++++++++++++++++++++++++++++++---------------
1 files changed, 1,124 insertions(+), 402 deletions(-)
diff --git a/kernel/kernel/trace/ring_buffer.c b/kernel/kernel/trace/ring_buffer.c
index 987d344..0938222 100644
--- a/kernel/kernel/trace/ring_buffer.c
+++ b/kernel/kernel/trace/ring_buffer.c
@@ -11,6 +11,7 @@
#include <linux/trace_seq.h>
#include <linux/spinlock.h>
#include <linux/irq_work.h>
+#include <linux/security.h>
#include <linux/uaccess.h>
#include <linux/hardirq.h>
#include <linux/kthread.h> /* for self test */
@@ -201,7 +202,7 @@
case RINGBUF_TYPE_DATA:
return rb_event_data_length(event);
default:
- BUG();
+ WARN_ON_ONCE(1);
}
/* not hit */
return 0;
@@ -257,7 +258,7 @@
{
if (extended_time(event))
event = skip_time_extend(event);
- BUG_ON(event->type_len > RINGBUF_TYPE_DATA_TYPE_LEN_MAX);
+ WARN_ON_ONCE(event->type_len > RINGBUF_TYPE_DATA_TYPE_LEN_MAX);
/* If length is in len field, then array[0] has the data */
if (event->type_len)
return (void *)&event->array[0];
@@ -277,6 +278,9 @@
#define for_each_buffer_cpu(buffer, cpu) \
for_each_cpu(cpu, buffer->cpumask)
+
+#define for_each_online_buffer_cpu(buffer, cpu) \
+ for_each_cpu_and(cpu, buffer->cpumask, cpu_online_mask)
#define TS_SHIFT 27
#define TS_MASK ((1ULL << TS_SHIFT) - 1)
@@ -307,8 +311,6 @@
#define RB_MISSED_EVENTS (1 << 31)
/* Missed count stored at end */
#define RB_MISSED_STORED (1 << 30)
-
-#define RB_MISSED_FLAGS (RB_MISSED_EVENTS|RB_MISSED_STORED)
struct buffer_data_page {
u64 time_stamp; /* page time stamp */
@@ -353,24 +355,11 @@
local_set(&bpage->commit, 0);
}
-/**
- * ring_buffer_page_len - the size of data on the page.
- * @page: The page to read
- *
- * Returns the amount of data on the page, including buffer page header.
- */
-size_t ring_buffer_page_len(void *page)
+static __always_inline unsigned int rb_page_commit(struct buffer_page *bpage)
{
- struct buffer_data_page *bpage = page;
-
- return (local_read(&bpage->commit) & ~RB_MISSED_FLAGS)
- + BUF_PAGE_HDR_SIZE;
+ return local_read(&bpage->page->commit);
}
-/*
- * Also stolen from mm/slob.c. Thanks to Mathieu Desnoyers for pointing
- * this issue out.
- */
static void free_buffer_page(struct buffer_page *bpage)
{
free_page((unsigned long)bpage->page);
@@ -426,6 +415,7 @@
struct irq_work work;
wait_queue_head_t waiters;
wait_queue_head_t full_waiters;
+ long wait_index;
bool waiters_pending;
bool full_waiters_pending;
bool wakeup_full;
@@ -437,11 +427,26 @@
struct rb_event_info {
u64 ts;
u64 delta;
+ u64 before;
+ u64 after;
unsigned long length;
struct buffer_page *tail_page;
int add_timestamp;
};
+/*
+ * Used for the add_timestamp
+ * NONE
+ * EXTEND - wants a time extend
+ * ABSOLUTE - the buffer requests all events to have absolute time stamps
+ * FORCE - force a full time stamp.
+ */
+enum {
+ RB_ADD_STAMP_NONE = 0,
+ RB_ADD_STAMP_EXTEND = BIT(1),
+ RB_ADD_STAMP_ABSOLUTE = BIT(2),
+ RB_ADD_STAMP_FORCE = BIT(3)
+};
/*
* Used for which event context the event is in.
* TRANSITION = 0
@@ -461,13 +466,36 @@
RB_CTX_MAX
};
+#if BITS_PER_LONG == 32
+#define RB_TIME_32
+#endif
+
+/* To test on 64 bit machines */
+//#define RB_TIME_32
+
+#ifdef RB_TIME_32
+
+struct rb_time_struct {
+ local_t cnt;
+ local_t top;
+ local_t bottom;
+};
+#else
+#include <asm/local64.h>
+struct rb_time_struct {
+ local64_t time;
+};
+#endif
+typedef struct rb_time_struct rb_time_t;
+
/*
* head_page == tail_page && head == tail then buffer is empty.
*/
struct ring_buffer_per_cpu {
int cpu;
atomic_t record_disabled;
- struct ring_buffer *buffer;
+ atomic_t resize_disabled;
+ struct trace_buffer *buffer;
raw_spinlock_t reader_lock; /* serialize readers */
arch_spinlock_t lock;
struct lock_class_key lock_key;
@@ -489,10 +517,18 @@
local_t dropped_events;
local_t committing;
local_t commits;
+ local_t pages_touched;
+ local_t pages_lost;
+ local_t pages_read;
+ long last_pages_touch;
+ size_t shortest_full;
unsigned long read;
unsigned long read_bytes;
- u64 write_stamp;
+ rb_time_t write_stamp;
+ rb_time_t before_stamp;
u64 read_stamp;
+ /* pages removed since last reset */
+ unsigned long pages_removed;
/* ring buffer pages to update, > 0 to add, < 0 to remove */
long nr_pages_to_update;
struct list_head new_pages; /* new pages to add */
@@ -502,11 +538,11 @@
struct rb_irq_work irq_work;
};
-struct ring_buffer {
+struct trace_buffer {
unsigned flags;
int cpus;
atomic_t record_disabled;
- atomic_t resize_disabled;
+ atomic_t resizing;
cpumask_var_t cpumask;
struct lock_class_key *reader_lock_key;
@@ -525,11 +561,257 @@
struct ring_buffer_iter {
struct ring_buffer_per_cpu *cpu_buffer;
unsigned long head;
+ unsigned long next_event;
struct buffer_page *head_page;
struct buffer_page *cache_reader_page;
unsigned long cache_read;
+ unsigned long cache_pages_removed;
u64 read_stamp;
+ u64 page_stamp;
+ struct ring_buffer_event *event;
+ int missed_events;
};
+
+#ifdef RB_TIME_32
+
+/*
+ * On 32 bit machines, local64_t is very expensive. As the ring
+ * buffer doesn't need all the features of a true 64 bit atomic,
+ * on 32 bit, it uses these functions (64 still uses local64_t).
+ *
+ * For the ring buffer, 64 bit required operations for the time is
+ * the following:
+ *
+ * - Only need 59 bits (uses 60 to make it even).
+ * - Reads may fail if it interrupted a modification of the time stamp.
+ * It will succeed if it did not interrupt another write even if
+ * the read itself is interrupted by a write.
+ * It returns whether it was successful or not.
+ *
+ * - Writes always succeed and will overwrite other writes and writes
+ * that were done by events interrupting the current write.
+ *
+ * - A write followed by a read of the same time stamp will always succeed,
+ * but may not contain the same value.
+ *
+ * - A cmpxchg will fail if it interrupted another write or cmpxchg.
+ * Other than that, it acts like a normal cmpxchg.
+ *
+ * The 60 bit time stamp is broken up by 30 bits in a top and bottom half
+ * (bottom being the least significant 30 bits of the 60 bit time stamp).
+ *
+ * The two most significant bits of each half holds a 2 bit counter (0-3).
+ * Each update will increment this counter by one.
+ * When reading the top and bottom, if the two counter bits match then the
+ * top and bottom together make a valid 60 bit number.
+ */
+#define RB_TIME_SHIFT 30
+#define RB_TIME_VAL_MASK ((1 << RB_TIME_SHIFT) - 1)
+
+static inline int rb_time_cnt(unsigned long val)
+{
+ return (val >> RB_TIME_SHIFT) & 3;
+}
+
+static inline u64 rb_time_val(unsigned long top, unsigned long bottom)
+{
+ u64 val;
+
+ val = top & RB_TIME_VAL_MASK;
+ val <<= RB_TIME_SHIFT;
+ val |= bottom & RB_TIME_VAL_MASK;
+
+ return val;
+}
+
+static inline bool __rb_time_read(rb_time_t *t, u64 *ret, unsigned long *cnt)
+{
+ unsigned long top, bottom;
+ unsigned long c;
+
+ /*
+ * If the read is interrupted by a write, then the cnt will
+ * be different. Loop until both top and bottom have been read
+ * without interruption.
+ */
+ do {
+ c = local_read(&t->cnt);
+ top = local_read(&t->top);
+ bottom = local_read(&t->bottom);
+ } while (c != local_read(&t->cnt));
+
+ *cnt = rb_time_cnt(top);
+
+ /* If top and bottom counts don't match, this interrupted a write */
+ if (*cnt != rb_time_cnt(bottom))
+ return false;
+
+ *ret = rb_time_val(top, bottom);
+ return true;
+}
+
+static bool rb_time_read(rb_time_t *t, u64 *ret)
+{
+ unsigned long cnt;
+
+ return __rb_time_read(t, ret, &cnt);
+}
+
+static inline unsigned long rb_time_val_cnt(unsigned long val, unsigned long cnt)
+{
+ return (val & RB_TIME_VAL_MASK) | ((cnt & 3) << RB_TIME_SHIFT);
+}
+
+static inline void rb_time_split(u64 val, unsigned long *top, unsigned long *bottom)
+{
+ *top = (unsigned long)((val >> RB_TIME_SHIFT) & RB_TIME_VAL_MASK);
+ *bottom = (unsigned long)(val & RB_TIME_VAL_MASK);
+}
+
+static inline void rb_time_val_set(local_t *t, unsigned long val, unsigned long cnt)
+{
+ val = rb_time_val_cnt(val, cnt);
+ local_set(t, val);
+}
+
+static void rb_time_set(rb_time_t *t, u64 val)
+{
+ unsigned long cnt, top, bottom;
+
+ rb_time_split(val, &top, &bottom);
+
+ /* Writes always succeed with a valid number even if it gets interrupted. */
+ do {
+ cnt = local_inc_return(&t->cnt);
+ rb_time_val_set(&t->top, top, cnt);
+ rb_time_val_set(&t->bottom, bottom, cnt);
+ } while (cnt != local_read(&t->cnt));
+}
+
+static inline bool
+rb_time_read_cmpxchg(local_t *l, unsigned long expect, unsigned long set)
+{
+ unsigned long ret;
+
+ ret = local_cmpxchg(l, expect, set);
+ return ret == expect;
+}
+
+static int rb_time_cmpxchg(rb_time_t *t, u64 expect, u64 set)
+{
+ unsigned long cnt, top, bottom;
+ unsigned long cnt2, top2, bottom2;
+ u64 val;
+
+ /* The cmpxchg always fails if it interrupted an update */
+ if (!__rb_time_read(t, &val, &cnt2))
+ return false;
+
+ if (val != expect)
+ return false;
+
+ cnt = local_read(&t->cnt);
+ if ((cnt & 3) != cnt2)
+ return false;
+
+ cnt2 = cnt + 1;
+
+ rb_time_split(val, &top, &bottom);
+ top = rb_time_val_cnt(top, cnt);
+ bottom = rb_time_val_cnt(bottom, cnt);
+
+ rb_time_split(set, &top2, &bottom2);
+ top2 = rb_time_val_cnt(top2, cnt2);
+ bottom2 = rb_time_val_cnt(bottom2, cnt2);
+
+ if (!rb_time_read_cmpxchg(&t->cnt, cnt, cnt2))
+ return false;
+ if (!rb_time_read_cmpxchg(&t->top, top, top2))
+ return false;
+ if (!rb_time_read_cmpxchg(&t->bottom, bottom, bottom2))
+ return false;
+ return true;
+}
+
+#else /* 64 bits */
+
+/* local64_t always succeeds */
+
+static inline bool rb_time_read(rb_time_t *t, u64 *ret)
+{
+ *ret = local64_read(&t->time);
+ return true;
+}
+static void rb_time_set(rb_time_t *t, u64 val)
+{
+ local64_set(&t->time, val);
+}
+
+static bool rb_time_cmpxchg(rb_time_t *t, u64 expect, u64 set)
+{
+ u64 val;
+ val = local64_cmpxchg(&t->time, expect, set);
+ return val == expect;
+}
+#endif
+
+/**
+ * ring_buffer_nr_pages - get the number of buffer pages in the ring buffer
+ * @buffer: The ring_buffer to get the number of pages from
+ * @cpu: The cpu of the ring_buffer to get the number of pages from
+ *
+ * Returns the number of pages used by a per_cpu buffer of the ring buffer.
+ */
+size_t ring_buffer_nr_pages(struct trace_buffer *buffer, int cpu)
+{
+ return buffer->buffers[cpu]->nr_pages;
+}
+
+/**
+ * ring_buffer_nr_pages_dirty - get the number of used pages in the ring buffer
+ * @buffer: The ring_buffer to get the number of pages from
+ * @cpu: The cpu of the ring_buffer to get the number of pages from
+ *
+ * Returns the number of pages that have content in the ring buffer.
+ */
+size_t ring_buffer_nr_dirty_pages(struct trace_buffer *buffer, int cpu)
+{
+ size_t read;
+ size_t lost;
+ size_t cnt;
+
+ read = local_read(&buffer->buffers[cpu]->pages_read);
+ lost = local_read(&buffer->buffers[cpu]->pages_lost);
+ cnt = local_read(&buffer->buffers[cpu]->pages_touched);
+
+ if (WARN_ON_ONCE(cnt < lost))
+ return 0;
+
+ cnt -= lost;
+
+ /* The reader can read an empty page, but not more than that */
+ if (cnt < read) {
+ WARN_ON_ONCE(read > cnt + 1);
+ return 0;
+ }
+
+ return cnt - read;
+}
+
+static __always_inline bool full_hit(struct trace_buffer *buffer, int cpu, int full)
+{
+ struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu];
+ size_t nr_pages;
+ size_t dirty;
+
+ nr_pages = cpu_buffer->nr_pages;
+ if (!nr_pages || !full)
+ return true;
+
+ dirty = ring_buffer_nr_dirty_pages(buffer, cpu);
+
+ return (dirty * 100) > (full * nr_pages);
+}
/*
* rb_wake_up_waiters - wake up tasks waiting for ring buffer input
@@ -542,27 +824,60 @@
struct rb_irq_work *rbwork = container_of(work, struct rb_irq_work, work);
wake_up_all(&rbwork->waiters);
- if (rbwork->wakeup_full) {
+ if (rbwork->full_waiters_pending || rbwork->wakeup_full) {
rbwork->wakeup_full = false;
+ rbwork->full_waiters_pending = false;
wake_up_all(&rbwork->full_waiters);
}
+}
+
+/**
+ * ring_buffer_wake_waiters - wake up any waiters on this ring buffer
+ * @buffer: The ring buffer to wake waiters on
+ *
+ * In the case of a file that represents a ring buffer is closing,
+ * it is prudent to wake up any waiters that are on this.
+ */
+void ring_buffer_wake_waiters(struct trace_buffer *buffer, int cpu)
+{
+ struct ring_buffer_per_cpu *cpu_buffer;
+ struct rb_irq_work *rbwork;
+
+ if (cpu == RING_BUFFER_ALL_CPUS) {
+
+ /* Wake up individual ones too. One level recursion */
+ for_each_buffer_cpu(buffer, cpu)
+ ring_buffer_wake_waiters(buffer, cpu);
+
+ rbwork = &buffer->irq_work;
+ } else {
+ cpu_buffer = buffer->buffers[cpu];
+ rbwork = &cpu_buffer->irq_work;
+ }
+
+ rbwork->wait_index++;
+ /* make sure the waiters see the new index */
+ smp_wmb();
+
+ rb_wake_up_waiters(&rbwork->work);
}
/**
* ring_buffer_wait - wait for input to the ring buffer
* @buffer: buffer to wait on
* @cpu: the cpu buffer to wait on
- * @full: wait until a full page is available, if @cpu != RING_BUFFER_ALL_CPUS
+ * @full: wait until the percentage of pages are available, if @cpu != RING_BUFFER_ALL_CPUS
*
* If @cpu == RING_BUFFER_ALL_CPUS then the task will wake up as soon
* as data is added to any of the @buffer's cpu buffers. Otherwise
* it will wait for data to be added to a specific cpu buffer.
*/
-int ring_buffer_wait(struct ring_buffer *buffer, int cpu, bool full)
+int ring_buffer_wait(struct trace_buffer *buffer, int cpu, int full)
{
- struct ring_buffer_per_cpu *uninitialized_var(cpu_buffer);
+ struct ring_buffer_per_cpu *cpu_buffer;
DEFINE_WAIT(wait);
struct rb_irq_work *work;
+ long wait_index;
int ret = 0;
/*
@@ -573,7 +888,7 @@
if (cpu == RING_BUFFER_ALL_CPUS) {
work = &buffer->irq_work;
/* Full only makes sense on per cpu reads */
- full = false;
+ full = 0;
} else {
if (!cpumask_test_cpu(cpu, buffer->cpumask))
return -ENODEV;
@@ -581,6 +896,7 @@
work = &cpu_buffer->irq_work;
}
+ wait_index = READ_ONCE(work->wait_index);
while (true) {
if (full)
@@ -625,19 +941,29 @@
!ring_buffer_empty_cpu(buffer, cpu)) {
unsigned long flags;
bool pagebusy;
+ bool done;
if (!full)
break;
raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags);
pagebusy = cpu_buffer->reader_page == cpu_buffer->commit_page;
- raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
+ done = !pagebusy && full_hit(buffer, cpu, full);
- if (!pagebusy)
+ if (!cpu_buffer->shortest_full ||
+ cpu_buffer->shortest_full > full)
+ cpu_buffer->shortest_full = full;
+ raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
+ if (done)
break;
}
schedule();
+
+ /* Make sure to see the new wait index */
+ smp_rmb();
+ if (wait_index != work->wait_index)
+ break;
}
if (full)
@@ -654,6 +980,7 @@
* @cpu: the cpu buffer to wait on
* @filp: the file descriptor
* @poll_table: The poll descriptor
+ * @full: wait until the percentage of pages are available, if @cpu != RING_BUFFER_ALL_CPUS
*
* If @cpu == RING_BUFFER_ALL_CPUS then the task will wake up as soon
* as data is added to any of the @buffer's cpu buffers. Otherwise
@@ -662,15 +989,16 @@
* Returns EPOLLIN | EPOLLRDNORM if data exists in the buffers,
* zero otherwise.
*/
-__poll_t ring_buffer_poll_wait(struct ring_buffer *buffer, int cpu,
- struct file *filp, poll_table *poll_table)
+__poll_t ring_buffer_poll_wait(struct trace_buffer *buffer, int cpu,
+ struct file *filp, poll_table *poll_table, int full)
{
struct ring_buffer_per_cpu *cpu_buffer;
struct rb_irq_work *work;
- if (cpu == RING_BUFFER_ALL_CPUS)
+ if (cpu == RING_BUFFER_ALL_CPUS) {
work = &buffer->irq_work;
- else {
+ full = 0;
+ } else {
if (!cpumask_test_cpu(cpu, buffer->cpumask))
return -EINVAL;
@@ -678,8 +1006,17 @@
work = &cpu_buffer->irq_work;
}
- poll_wait(filp, &work->waiters, poll_table);
- work->waiters_pending = true;
+ if (full) {
+ poll_wait(filp, &work->full_waiters, poll_table);
+ work->full_waiters_pending = true;
+ if (!cpu_buffer->shortest_full ||
+ cpu_buffer->shortest_full > full)
+ cpu_buffer->shortest_full = full;
+ } else {
+ poll_wait(filp, &work->waiters, poll_table);
+ work->waiters_pending = true;
+ }
+
/*
* There's a tight race between setting the waiters_pending and
* checking if the ring buffer is empty. Once the waiters_pending bit
@@ -694,6 +1031,9 @@
* will fix it later.
*/
smp_mb();
+
+ if (full)
+ return full_hit(buffer, cpu, full) ? EPOLLIN | EPOLLRDNORM : 0;
if ((cpu == RING_BUFFER_ALL_CPUS && !ring_buffer_empty(buffer)) ||
(cpu != RING_BUFFER_ALL_CPUS && !ring_buffer_empty_cpu(buffer, cpu)))
@@ -720,13 +1060,21 @@
/* Up this if you want to test the TIME_EXTENTS and normalization */
#define DEBUG_SHIFT 0
-static inline u64 rb_time_stamp(struct ring_buffer *buffer)
+static inline u64 rb_time_stamp(struct trace_buffer *buffer)
{
+ u64 ts;
+
+ /* Skip retpolines :-( */
+ if (IS_ENABLED(CONFIG_RETPOLINE) && likely(buffer->clock == trace_clock_local))
+ ts = trace_clock_local();
+ else
+ ts = buffer->clock();
+
/* shift to debug/test normalization and TIME_EXTENTS */
- return buffer->clock() << DEBUG_SHIFT;
+ return ts << DEBUG_SHIFT;
}
-u64 ring_buffer_time_stamp(struct ring_buffer *buffer, int cpu)
+u64 ring_buffer_time_stamp(struct trace_buffer *buffer, int cpu)
{
u64 time;
@@ -738,7 +1086,7 @@
}
EXPORT_SYMBOL_GPL(ring_buffer_time_stamp);
-void ring_buffer_normalize_time_stamp(struct ring_buffer *buffer,
+void ring_buffer_normalize_time_stamp(struct trace_buffer *buffer,
int cpu, u64 *ts)
{
/* Just stupid testing the normalize function and deltas */
@@ -1056,6 +1404,7 @@
old_write = local_add_return(RB_WRITE_INTCNT, &next_page->write);
old_entries = local_add_return(RB_WRITE_INTCNT, &next_page->entries);
+ local_inc(&cpu_buffer->pages_touched);
/*
* Just make sure we have seen our old_write and synchronize
* with any interrupts that come in.
@@ -1109,19 +1458,6 @@
}
/**
- * rb_check_list - make sure a pointer to a list has the last bits zero
- */
-static int rb_check_list(struct ring_buffer_per_cpu *cpu_buffer,
- struct list_head *list)
-{
- if (RB_WARN_ON(cpu_buffer, rb_list_head(list->prev) != list->prev))
- return 1;
- if (RB_WARN_ON(cpu_buffer, rb_list_head(list->next) != list->next))
- return 1;
- return 0;
-}
-
-/**
* rb_check_pages - integrity check of buffer pages
* @cpu_buffer: CPU buffer with pages to test
*
@@ -1130,35 +1466,26 @@
*/
static int rb_check_pages(struct ring_buffer_per_cpu *cpu_buffer)
{
- struct list_head *head = cpu_buffer->pages;
- struct buffer_page *bpage, *tmp;
+ struct list_head *head = rb_list_head(cpu_buffer->pages);
+ struct list_head *tmp;
- /* Reset the head page if it exists */
- if (cpu_buffer->head_page)
- rb_set_head_page(cpu_buffer);
-
- rb_head_page_deactivate(cpu_buffer);
-
- if (RB_WARN_ON(cpu_buffer, head->next->prev != head))
- return -1;
- if (RB_WARN_ON(cpu_buffer, head->prev->next != head))
+ if (RB_WARN_ON(cpu_buffer,
+ rb_list_head(rb_list_head(head->next)->prev) != head))
return -1;
- if (rb_check_list(cpu_buffer, head))
+ if (RB_WARN_ON(cpu_buffer,
+ rb_list_head(rb_list_head(head->prev)->next) != head))
return -1;
- list_for_each_entry_safe(bpage, tmp, head, list) {
+ for (tmp = rb_list_head(head->next); tmp != head; tmp = rb_list_head(tmp->next)) {
if (RB_WARN_ON(cpu_buffer,
- bpage->list.next->prev != &bpage->list))
+ rb_list_head(rb_list_head(tmp->next)->prev) != tmp))
return -1;
+
if (RB_WARN_ON(cpu_buffer,
- bpage->list.prev->next != &bpage->list))
- return -1;
- if (rb_check_list(cpu_buffer, &bpage->list))
+ rb_list_head(rb_list_head(tmp->prev)->next) != tmp))
return -1;
}
-
- rb_head_page_activate(cpu_buffer);
return 0;
}
@@ -1260,7 +1587,7 @@
}
static struct ring_buffer_per_cpu *
-rb_allocate_cpu_buffer(struct ring_buffer *buffer, long nr_pages, int cpu)
+rb_allocate_cpu_buffer(struct trace_buffer *buffer, long nr_pages, int cpu)
{
struct ring_buffer_per_cpu *cpu_buffer;
struct buffer_page *bpage;
@@ -1325,11 +1652,13 @@
struct list_head *head = cpu_buffer->pages;
struct buffer_page *bpage, *tmp;
+ irq_work_sync(&cpu_buffer->irq_work.work);
+
free_buffer_page(cpu_buffer->reader_page);
- rb_head_page_deactivate(cpu_buffer);
-
if (head) {
+ rb_head_page_deactivate(cpu_buffer);
+
list_for_each_entry_safe(bpage, tmp, head, list) {
list_del_init(&bpage->list);
free_buffer_page(bpage);
@@ -1345,16 +1674,17 @@
* __ring_buffer_alloc - allocate a new ring_buffer
* @size: the size in bytes per cpu that is needed.
* @flags: attributes to set for the ring buffer.
+ * @key: ring buffer reader_lock_key.
*
* Currently the only flag that is available is the RB_FL_OVERWRITE
* flag. This flag means that the buffer will overwrite old data
* when the buffer wraps. If this flag is not set, the buffer will
* drop data when the tail hits the head.
*/
-struct ring_buffer *__ring_buffer_alloc(unsigned long size, unsigned flags,
+struct trace_buffer *__ring_buffer_alloc(unsigned long size, unsigned flags,
struct lock_class_key *key)
{
- struct ring_buffer *buffer;
+ struct trace_buffer *buffer;
long nr_pages;
int bsize;
int cpu;
@@ -1424,11 +1754,13 @@
* @buffer: the buffer to free.
*/
void
-ring_buffer_free(struct ring_buffer *buffer)
+ring_buffer_free(struct trace_buffer *buffer)
{
int cpu;
cpuhp_state_remove_instance(CPUHP_TRACE_RB_PREPARE, &buffer->node);
+
+ irq_work_sync(&buffer->irq_work.work);
for_each_buffer_cpu(buffer, cpu)
rb_free_cpu_buffer(buffer->buffers[cpu]);
@@ -1440,18 +1772,18 @@
}
EXPORT_SYMBOL_GPL(ring_buffer_free);
-void ring_buffer_set_clock(struct ring_buffer *buffer,
+void ring_buffer_set_clock(struct trace_buffer *buffer,
u64 (*clock)(void))
{
buffer->clock = clock;
}
-void ring_buffer_set_time_stamp_abs(struct ring_buffer *buffer, bool abs)
+void ring_buffer_set_time_stamp_abs(struct trace_buffer *buffer, bool abs)
{
buffer->time_stamp_abs = abs;
}
-bool ring_buffer_time_stamp_abs(struct ring_buffer *buffer)
+bool ring_buffer_time_stamp_abs(struct trace_buffer *buffer)
{
return buffer->time_stamp_abs;
}
@@ -1509,6 +1841,8 @@
to_remove = rb_list_head(to_remove)->next;
head_bit |= (unsigned long)to_remove & RB_PAGE_HEAD;
}
+ /* Read iterators need to reset themselves when some pages removed */
+ cpu_buffer->pages_removed += nr_removed;
next_page = rb_list_head(to_remove)->next;
@@ -1529,12 +1863,6 @@
if (head_bit)
cpu_buffer->head_page = list_entry(next_page,
struct buffer_page, list);
-
- /*
- * change read pointer to make sure any read iterators reset
- * themselves
- */
- cpu_buffer->read = 0;
/* pages are removed, resume tracing and then free the pages */
atomic_dec(&cpu_buffer->record_disabled);
@@ -1563,7 +1891,8 @@
* Increment overrun to account for the lost events.
*/
local_add(page_entries, &cpu_buffer->overrun);
- local_sub(BUF_PAGE_SIZE, &cpu_buffer->entries_bytes);
+ local_sub(rb_page_commit(to_remove_page), &cpu_buffer->entries_bytes);
+ local_inc(&cpu_buffer->pages_lost);
}
/*
@@ -1689,7 +2018,7 @@
*
* Returns 0 on success and < 0 on failure.
*/
-int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size,
+int ring_buffer_resize(struct trace_buffer *buffer, unsigned long size,
int cpu_id)
{
struct ring_buffer_per_cpu *cpu_buffer;
@@ -1715,18 +2044,24 @@
size = nr_pages * BUF_PAGE_SIZE;
- /*
- * Don't succeed if resizing is disabled, as a reader might be
- * manipulating the ring buffer and is expecting a sane state while
- * this is true.
- */
- if (atomic_read(&buffer->resize_disabled))
- return -EBUSY;
-
/* prevent another thread from changing buffer sizes */
mutex_lock(&buffer->mutex);
+ atomic_inc(&buffer->resizing);
if (cpu_id == RING_BUFFER_ALL_CPUS) {
+ /*
+ * Don't succeed if resizing is disabled, as a reader might be
+ * manipulating the ring buffer and is expecting a sane state while
+ * this is true.
+ */
+ for_each_buffer_cpu(buffer, cpu) {
+ cpu_buffer = buffer->buffers[cpu];
+ if (atomic_read(&cpu_buffer->resize_disabled)) {
+ err = -EBUSY;
+ goto out_err_unlock;
+ }
+ }
+
/* calculate the pages to update */
for_each_buffer_cpu(buffer, cpu) {
cpu_buffer = buffer->buffers[cpu];
@@ -1749,6 +2084,8 @@
err = -ENOMEM;
goto out_err;
}
+
+ cond_resched();
}
get_online_cpus();
@@ -1794,6 +2131,16 @@
if (nr_pages == cpu_buffer->nr_pages)
goto out;
+ /*
+ * Don't succeed if resizing is disabled, as a reader might be
+ * manipulating the ring buffer and is expecting a sane state while
+ * this is true.
+ */
+ if (atomic_read(&cpu_buffer->resize_disabled)) {
+ err = -EBUSY;
+ goto out_err_unlock;
+ }
+
cpu_buffer->nr_pages_to_update = nr_pages -
cpu_buffer->nr_pages;
@@ -1836,7 +2183,7 @@
* There could have been a race between checking
* record_disable and incrementing it.
*/
- synchronize_sched();
+ synchronize_rcu();
for_each_buffer_cpu(buffer, cpu) {
cpu_buffer = buffer->buffers[cpu];
rb_check_pages(cpu_buffer);
@@ -1844,6 +2191,7 @@
atomic_dec(&buffer->record_disabled);
}
+ atomic_dec(&buffer->resizing);
mutex_unlock(&buffer->mutex);
return 0;
@@ -1863,12 +2211,14 @@
free_buffer_page(bpage);
}
}
+ out_err_unlock:
+ atomic_dec(&buffer->resizing);
mutex_unlock(&buffer->mutex);
return err;
}
EXPORT_SYMBOL_GPL(ring_buffer_resize);
-void ring_buffer_change_overwrite(struct ring_buffer *buffer, int val)
+void ring_buffer_change_overwrite(struct trace_buffer *buffer, int val)
{
mutex_lock(&buffer->mutex);
if (val)
@@ -1891,15 +2241,63 @@
cpu_buffer->reader_page->read);
}
-static __always_inline struct ring_buffer_event *
+static struct ring_buffer_event *
rb_iter_head_event(struct ring_buffer_iter *iter)
{
- return __rb_page_index(iter->head_page, iter->head);
-}
+ struct ring_buffer_event *event;
+ struct buffer_page *iter_head_page = iter->head_page;
+ unsigned long commit;
+ unsigned length;
-static __always_inline unsigned rb_page_commit(struct buffer_page *bpage)
-{
- return local_read(&bpage->page->commit);
+ if (iter->head != iter->next_event)
+ return iter->event;
+
+ /*
+ * When the writer goes across pages, it issues a cmpxchg which
+ * is a mb(), which will synchronize with the rmb here.
+ * (see rb_tail_page_update() and __rb_reserve_next())
+ */
+ commit = rb_page_commit(iter_head_page);
+ smp_rmb();
+
+ /* An event needs to be at least 8 bytes in size */
+ if (iter->head > commit - 8)
+ goto reset;
+
+ event = __rb_page_index(iter_head_page, iter->head);
+ length = rb_event_length(event);
+
+ /*
+ * READ_ONCE() doesn't work on functions and we don't want the
+ * compiler doing any crazy optimizations with length.
+ */
+ barrier();
+
+ if ((iter->head + length) > commit || length > BUF_MAX_DATA_SIZE)
+ /* Writer corrupted the read? */
+ goto reset;
+
+ memcpy(iter->event, event, length);
+ /*
+ * If the page stamp is still the same after this rmb() then the
+ * event was safely copied without the writer entering the page.
+ */
+ smp_rmb();
+
+ /* Make sure the page didn't change since we read this */
+ if (iter->page_stamp != iter_head_page->page->time_stamp ||
+ commit > rb_page_commit(iter_head_page))
+ goto reset;
+
+ iter->next_event = iter->head + length;
+ return iter->event;
+ reset:
+ /* Reset to the beginning */
+ iter->page_stamp = iter->read_stamp = iter->head_page->page->time_stamp;
+ iter->head = 0;
+ iter->next_event = 0;
+ iter->missed_events = 1;
+ return NULL;
}
/* Size is determined by what has been committed */
@@ -1937,8 +2335,9 @@
else
rb_inc_page(cpu_buffer, &iter->head_page);
- iter->read_stamp = iter->head_page->page->time_stamp;
+ iter->page_stamp = iter->read_stamp = iter->head_page->page->time_stamp;
iter->head = 0;
+ iter->next_event = 0;
}
/*
@@ -1987,7 +2386,8 @@
* the counters.
*/
local_add(entries, &cpu_buffer->overrun);
- local_sub(BUF_PAGE_SIZE, &cpu_buffer->entries_bytes);
+ local_sub(rb_page_commit(next_page), &cpu_buffer->entries_bytes);
+ local_inc(&cpu_buffer->pages_lost);
/*
* The entries will be zeroed out when we move the
@@ -2129,9 +2529,6 @@
event = __rb_page_index(tail_page, tail);
- /* account for padding bytes */
- local_add(BUF_PAGE_SIZE - tail, &cpu_buffer->entries_bytes);
-
/*
* Save the original length to the meta data.
* This will be used by the reader to add lost event
@@ -2145,7 +2542,8 @@
* write counter enough to allow another writer to slip
* in on this page.
* We put in a discarded commit instead, to make sure
- * that this space is not used again.
+ * that this space is not used again, and this space will
+ * not be accounted into 'entries_bytes'.
*
* If we are less than the minimum size, we don't need to
* worry about it.
@@ -2155,6 +2553,9 @@
/* Mark the rest of the page with padding */
rb_event_set_padding(event);
+
+ /* Make sure the padding is visible before the write update */
+ smp_wmb();
/* Set the write back to the previous setting */
local_sub(length, &tail_page->write);
@@ -2166,6 +2567,12 @@
event->type_len = RINGBUF_TYPE_PADDING;
/* time delta must be non zero */
event->time_delta = 1;
+
+ /* account for padding bytes */
+ local_add(BUF_PAGE_SIZE - tail, &cpu_buffer->entries_bytes);
+
+ /* Make sure the padding is visible before the tail_page->write update */
+ smp_wmb();
/* Set write to end of buffer */
length = (tail + length) - BUF_PAGE_SIZE;
@@ -2183,7 +2590,7 @@
{
struct buffer_page *tail_page = info->tail_page;
struct buffer_page *commit_page = cpu_buffer->commit_page;
- struct ring_buffer *buffer = cpu_buffer->buffer;
+ struct trace_buffer *buffer = cpu_buffer->buffer;
struct buffer_page *next_page;
int ret;
@@ -2280,8 +2687,8 @@
return NULL;
}
-/* Slow path, do not inline */
-static noinline struct ring_buffer_event *
+/* Slow path */
+static struct ring_buffer_event *
rb_add_time_stamp(struct ring_buffer_event *event, u64 delta, bool abs)
{
if (abs)
@@ -2305,13 +2712,73 @@
static inline bool rb_event_is_commit(struct ring_buffer_per_cpu *cpu_buffer,
struct ring_buffer_event *event);
+#ifndef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK
+static inline bool sched_clock_stable(void)
+{
+ return true;
+}
+#endif
+
+static void
+rb_check_timestamp(struct ring_buffer_per_cpu *cpu_buffer,
+ struct rb_event_info *info)
+{
+ u64 write_stamp;
+
+ WARN_ONCE(1, "Delta way too big! %llu ts=%llu before=%llu after=%llu write stamp=%llu\n%s",
+ (unsigned long long)info->delta,
+ (unsigned long long)info->ts,
+ (unsigned long long)info->before,
+ (unsigned long long)info->after,
+ (unsigned long long)(rb_time_read(&cpu_buffer->write_stamp, &write_stamp) ? write_stamp : 0),
+ sched_clock_stable() ? "" :
+ "If you just came from a suspend/resume,\n"
+ "please switch to the trace global clock:\n"
+ " echo global > /sys/kernel/debug/tracing/trace_clock\n"
+ "or add trace_clock=global to the kernel command line\n");
+}
+
+static void rb_add_timestamp(struct ring_buffer_per_cpu *cpu_buffer,
+ struct ring_buffer_event **event,
+ struct rb_event_info *info,
+ u64 *delta,
+ unsigned int *length)
+{
+ bool abs = info->add_timestamp &
+ (RB_ADD_STAMP_FORCE | RB_ADD_STAMP_ABSOLUTE);
+
+ if (unlikely(info->delta > (1ULL << 59))) {
+ /* did the clock go backwards */
+ if (info->before == info->after && info->before > info->ts) {
+ /* not interrupted */
+ static int once;
+
+ /*
+ * This is possible with a recalibrating of the TSC.
+ * Do not produce a call stack, but just report it.
+ */
+ if (!once) {
+ once++;
+ pr_warn("Ring buffer clock went backwards: %llu -> %llu\n",
+ info->before, info->ts);
+ }
+ } else
+ rb_check_timestamp(cpu_buffer, info);
+ if (!abs)
+ info->delta = 0;
+ }
+ *event = rb_add_time_stamp(*event, info->delta, abs);
+ *length -= RB_LEN_TIME_EXTEND;
+ *delta = 0;
+}
+
/**
* rb_update_event - update event type and data
+ * @cpu_buffer: The per cpu buffer of the @event
* @event: the event to update
- * @type: the type of event
- * @length: the size of the event field in the ring buffer
+ * @info: The info to update the @event with (contains length and delta)
*
- * Update the type and data fields of the event. The length
+ * Update the type and data fields of the @event. The length
* is the actual size that is written to the ring buffer,
* and with this, we can determine what to place into the
* data field.
@@ -2324,21 +2791,12 @@
unsigned length = info->length;
u64 delta = info->delta;
- /* Only a commit updates the timestamp */
- if (unlikely(!rb_event_is_commit(cpu_buffer, event)))
- delta = 0;
-
/*
* If we need to add a timestamp, then we
* add it to the start of the reserved space.
*/
- if (unlikely(info->add_timestamp)) {
- bool abs = ring_buffer_time_stamp_abs(cpu_buffer->buffer);
-
- event = rb_add_time_stamp(event, abs ? info->delta : delta, abs);
- length -= RB_LEN_TIME_EXTEND;
- delta = 0;
- }
+ if (unlikely(info->add_timestamp))
+ rb_add_timestamp(cpu_buffer, &event, info, &delta, &length);
event->time_delta = delta;
length -= RB_EVNT_HDR_SIZE;
@@ -2381,12 +2839,38 @@
return length;
}
-#ifndef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK
-static inline bool sched_clock_stable(void)
+static __always_inline bool
+rb_event_is_commit(struct ring_buffer_per_cpu *cpu_buffer,
+ struct ring_buffer_event *event)
{
- return true;
+ unsigned long addr = (unsigned long)event;
+ unsigned long index;
+
+ index = rb_event_index(event);
+ addr &= PAGE_MASK;
+
+ return cpu_buffer->commit_page->page == (void *)addr &&
+ rb_commit_index(cpu_buffer) == index;
}
-#endif
+
+static u64 rb_time_delta(struct ring_buffer_event *event)
+{
+ switch (event->type_len) {
+ case RINGBUF_TYPE_PADDING:
+ return 0;
+
+ case RINGBUF_TYPE_TIME_EXTEND:
+ return ring_buffer_event_time_stamp(event);
+
+ case RINGBUF_TYPE_TIME_STAMP:
+ return 0;
+
+ case RINGBUF_TYPE_DATA:
+ return event->time_delta;
+ default:
+ return 0;
+ }
+}
static inline int
rb_try_to_discard(struct ring_buffer_per_cpu *cpu_buffer,
@@ -2396,6 +2880,8 @@
struct buffer_page *bpage;
unsigned long index;
unsigned long addr;
+ u64 write_stamp;
+ u64 delta;
new_index = rb_event_index(event);
old_index = new_index + rb_event_ts_length(event);
@@ -2404,10 +2890,43 @@
bpage = READ_ONCE(cpu_buffer->tail_page);
+ delta = rb_time_delta(event);
+
+ if (!rb_time_read(&cpu_buffer->write_stamp, &write_stamp))
+ return 0;
+
+ /* Make sure the write stamp is read before testing the location */
+ barrier();
+
if (bpage->page == (void *)addr && rb_page_write(bpage) == old_index) {
unsigned long write_mask =
local_read(&bpage->write) & ~RB_WRITE_MASK;
unsigned long event_length = rb_event_length(event);
+
+ /* Something came in, can't discard */
+ if (!rb_time_cmpxchg(&cpu_buffer->write_stamp,
+ write_stamp, write_stamp - delta))
+ return 0;
+
+ /*
+ * It's possible that the event time delta is zero
+ * (has the same time stamp as the previous event)
+ * in which case write_stamp and before_stamp could
+ * be the same. In such a case, force before_stamp
+ * to be different than write_stamp. It doesn't
+ * matter what it is, as long as its different.
+ */
+ if (!delta)
+ rb_time_set(&cpu_buffer->before_stamp, 0);
+
+ /*
+ * If an event were to come in now, it would see that the
+ * write_stamp and the before_stamp are different, and assume
+ * that this event just added itself before updating
+ * the write stamp. The interrupting event will fix the
+ * write stamp for us, and use the before stamp as its delta.
+ */
+
/*
* This is on the tail page. It is possible that
* a write could come in and move the tail page
@@ -2456,19 +2975,21 @@
if (RB_WARN_ON(cpu_buffer,
rb_is_reader_page(cpu_buffer->tail_page)))
return;
+ /*
+ * No need for a memory barrier here, as the update
+ * of the tail_page did it for this page.
+ */
local_set(&cpu_buffer->commit_page->page->commit,
rb_page_write(cpu_buffer->commit_page));
rb_inc_page(cpu_buffer, &cpu_buffer->commit_page);
- /* Only update the write stamp if the page has an event */
- if (rb_page_write(cpu_buffer->commit_page))
- cpu_buffer->write_stamp =
- cpu_buffer->commit_page->page->time_stamp;
/* add barrier to keep gcc from optimizing too much */
barrier();
}
while (rb_commit_index(cpu_buffer) !=
rb_page_write(cpu_buffer->commit_page)) {
+ /* Make sure the readers see the content of what is committed. */
+ smp_wmb();
local_set(&cpu_buffer->commit_page->page->commit,
rb_page_write(cpu_buffer->commit_page));
RB_WARN_ON(cpu_buffer,
@@ -2534,62 +3055,16 @@
event->time_delta = 1;
}
-static __always_inline bool
-rb_event_is_commit(struct ring_buffer_per_cpu *cpu_buffer,
- struct ring_buffer_event *event)
-{
- unsigned long addr = (unsigned long)event;
- unsigned long index;
-
- index = rb_event_index(event);
- addr &= PAGE_MASK;
-
- return cpu_buffer->commit_page->page == (void *)addr &&
- rb_commit_index(cpu_buffer) == index;
-}
-
-static __always_inline void
-rb_update_write_stamp(struct ring_buffer_per_cpu *cpu_buffer,
- struct ring_buffer_event *event)
-{
- u64 delta;
-
- /*
- * The event first in the commit queue updates the
- * time stamp.
- */
- if (rb_event_is_commit(cpu_buffer, event)) {
- /*
- * A commit event that is first on a page
- * updates the write timestamp with the page stamp
- */
- if (!rb_event_index(event))
- cpu_buffer->write_stamp =
- cpu_buffer->commit_page->page->time_stamp;
- else if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) {
- delta = ring_buffer_event_time_stamp(event);
- cpu_buffer->write_stamp += delta;
- } else if (event->type_len == RINGBUF_TYPE_TIME_STAMP) {
- delta = ring_buffer_event_time_stamp(event);
- cpu_buffer->write_stamp = delta;
- } else
- cpu_buffer->write_stamp += event->time_delta;
- }
-}
-
static void rb_commit(struct ring_buffer_per_cpu *cpu_buffer,
struct ring_buffer_event *event)
{
local_inc(&cpu_buffer->entries);
- rb_update_write_stamp(cpu_buffer, event);
rb_end_commit(cpu_buffer);
}
static __always_inline void
-rb_wakeups(struct ring_buffer *buffer, struct ring_buffer_per_cpu *cpu_buffer)
+rb_wakeups(struct trace_buffer *buffer, struct ring_buffer_per_cpu *cpu_buffer)
{
- bool pagebusy;
-
if (buffer->irq_work.waiters_pending) {
buffer->irq_work.waiters_pending = false;
/* irq_work_queue() supplies it's own memory barriers */
@@ -2602,14 +3077,24 @@
irq_work_queue(&cpu_buffer->irq_work.work);
}
- pagebusy = cpu_buffer->reader_page == cpu_buffer->commit_page;
+ if (cpu_buffer->last_pages_touch == local_read(&cpu_buffer->pages_touched))
+ return;
- if (!pagebusy && cpu_buffer->irq_work.full_waiters_pending) {
- cpu_buffer->irq_work.wakeup_full = true;
- cpu_buffer->irq_work.full_waiters_pending = false;
- /* irq_work_queue() supplies it's own memory barriers */
- irq_work_queue(&cpu_buffer->irq_work.work);
- }
+ if (cpu_buffer->reader_page == cpu_buffer->commit_page)
+ return;
+
+ if (!cpu_buffer->irq_work.full_waiters_pending)
+ return;
+
+ cpu_buffer->last_pages_touch = local_read(&cpu_buffer->pages_touched);
+
+ if (!full_hit(buffer, cpu_buffer->cpu, cpu_buffer->shortest_full))
+ return;
+
+ cpu_buffer->irq_work.wakeup_full = true;
+ cpu_buffer->irq_work.full_waiters_pending = false;
+ /* irq_work_queue() supplies it's own memory barriers */
+ irq_work_queue(&cpu_buffer->irq_work.work);
}
/*
@@ -2727,7 +3212,7 @@
* Call this function before calling another ring_buffer_lock_reserve() and
* call ring_buffer_nest_end() after the nested ring_buffer_unlock_commit().
*/
-void ring_buffer_nest_start(struct ring_buffer *buffer)
+void ring_buffer_nest_start(struct trace_buffer *buffer)
{
struct ring_buffer_per_cpu *cpu_buffer;
int cpu;
@@ -2747,7 +3232,7 @@
* Must be called after ring_buffer_nest_start() and after the
* ring_buffer_unlock_commit().
*/
-void ring_buffer_nest_end(struct ring_buffer *buffer)
+void ring_buffer_nest_end(struct trace_buffer *buffer)
{
struct ring_buffer_per_cpu *cpu_buffer;
int cpu;
@@ -2769,7 +3254,7 @@
*
* Must be paired with ring_buffer_lock_reserve.
*/
-int ring_buffer_unlock_commit(struct ring_buffer *buffer,
+int ring_buffer_unlock_commit(struct trace_buffer *buffer,
struct ring_buffer_event *event)
{
struct ring_buffer_per_cpu *cpu_buffer;
@@ -2789,57 +3274,135 @@
}
EXPORT_SYMBOL_GPL(ring_buffer_unlock_commit);
-static noinline void
-rb_handle_timestamp(struct ring_buffer_per_cpu *cpu_buffer,
- struct rb_event_info *info)
-{
- WARN_ONCE(info->delta > (1ULL << 59),
- KERN_WARNING "Delta way too big! %llu ts=%llu write stamp = %llu\n%s",
- (unsigned long long)info->delta,
- (unsigned long long)info->ts,
- (unsigned long long)cpu_buffer->write_stamp,
- sched_clock_stable() ? "" :
- "If you just came from a suspend/resume,\n"
- "please switch to the trace global clock:\n"
- " echo global > /sys/kernel/debug/tracing/trace_clock\n"
- "or add trace_clock=global to the kernel command line\n");
- info->add_timestamp = 1;
-}
-
static struct ring_buffer_event *
__rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
struct rb_event_info *info)
{
struct ring_buffer_event *event;
struct buffer_page *tail_page;
- unsigned long tail, write;
-
- /*
- * If the time delta since the last event is too big to
- * hold in the time field of the event, then we append a
- * TIME EXTEND event ahead of the data event.
- */
- if (unlikely(info->add_timestamp))
- info->length += RB_LEN_TIME_EXTEND;
+ unsigned long tail, write, w;
+ bool a_ok;
+ bool b_ok;
/* Don't let the compiler play games with cpu_buffer->tail_page */
tail_page = info->tail_page = READ_ONCE(cpu_buffer->tail_page);
- write = local_add_return(info->length, &tail_page->write);
+
+ /*A*/ w = local_read(&tail_page->write) & RB_WRITE_MASK;
+ barrier();
+ b_ok = rb_time_read(&cpu_buffer->before_stamp, &info->before);
+ a_ok = rb_time_read(&cpu_buffer->write_stamp, &info->after);
+ barrier();
+ info->ts = rb_time_stamp(cpu_buffer->buffer);
+
+ if ((info->add_timestamp & RB_ADD_STAMP_ABSOLUTE)) {
+ info->delta = info->ts;
+ } else {
+ /*
+ * If interrupting an event time update, we may need an
+ * absolute timestamp.
+ * Don't bother if this is the start of a new page (w == 0).
+ */
+ if (unlikely(!a_ok || !b_ok || (info->before != info->after && w))) {
+ info->add_timestamp |= RB_ADD_STAMP_FORCE | RB_ADD_STAMP_EXTEND;
+ info->length += RB_LEN_TIME_EXTEND;
+ } else {
+ info->delta = info->ts - info->after;
+ if (unlikely(test_time_stamp(info->delta))) {
+ info->add_timestamp |= RB_ADD_STAMP_EXTEND;
+ info->length += RB_LEN_TIME_EXTEND;
+ }
+ }
+ }
+
+ /*B*/ rb_time_set(&cpu_buffer->before_stamp, info->ts);
+
+ /*C*/ write = local_add_return(info->length, &tail_page->write);
/* set write to only the index of the write */
write &= RB_WRITE_MASK;
+
tail = write - info->length;
+
+ /* See if we shot pass the end of this buffer page */
+ if (unlikely(write > BUF_PAGE_SIZE)) {
+ /* before and after may now different, fix it up*/
+ b_ok = rb_time_read(&cpu_buffer->before_stamp, &info->before);
+ a_ok = rb_time_read(&cpu_buffer->write_stamp, &info->after);
+ if (a_ok && b_ok && info->before != info->after)
+ (void)rb_time_cmpxchg(&cpu_buffer->before_stamp,
+ info->before, info->after);
+ return rb_move_tail(cpu_buffer, tail, info);
+ }
+
+ if (likely(tail == w)) {
+ u64 save_before;
+ bool s_ok;
+
+ /* Nothing interrupted us between A and C */
+ /*D*/ rb_time_set(&cpu_buffer->write_stamp, info->ts);
+ barrier();
+ /*E*/ s_ok = rb_time_read(&cpu_buffer->before_stamp, &save_before);
+ RB_WARN_ON(cpu_buffer, !s_ok);
+ if (likely(!(info->add_timestamp &
+ (RB_ADD_STAMP_FORCE | RB_ADD_STAMP_ABSOLUTE))))
+ /* This did not interrupt any time update */
+ info->delta = info->ts - info->after;
+ else
+ /* Just use full timestamp for inerrupting event */
+ info->delta = info->ts;
+ barrier();
+ if (unlikely(info->ts != save_before)) {
+ /* SLOW PATH - Interrupted between C and E */
+
+ a_ok = rb_time_read(&cpu_buffer->write_stamp, &info->after);
+ RB_WARN_ON(cpu_buffer, !a_ok);
+
+ /* Write stamp must only go forward */
+ if (save_before > info->after) {
+ /*
+ * We do not care about the result, only that
+ * it gets updated atomically.
+ */
+ (void)rb_time_cmpxchg(&cpu_buffer->write_stamp,
+ info->after, save_before);
+ }
+ }
+ } else {
+ u64 ts;
+ /* SLOW PATH - Interrupted between A and C */
+ a_ok = rb_time_read(&cpu_buffer->write_stamp, &info->after);
+ /* Was interrupted before here, write_stamp must be valid */
+ RB_WARN_ON(cpu_buffer, !a_ok);
+ ts = rb_time_stamp(cpu_buffer->buffer);
+ barrier();
+ /*E*/ if (write == (local_read(&tail_page->write) & RB_WRITE_MASK) &&
+ info->after < ts &&
+ rb_time_cmpxchg(&cpu_buffer->write_stamp,
+ info->after, ts)) {
+ /* Nothing came after this event between C and E */
+ info->delta = ts - info->after;
+ info->ts = ts;
+ } else {
+ /*
+ * Interrupted beween C and E:
+ * Lost the previous events time stamp. Just set the
+ * delta to zero, and this will be the same time as
+ * the event this event interrupted. And the events that
+ * came after this will still be correct (as they would
+ * have built their delta on the previous event.
+ */
+ info->delta = 0;
+ }
+ info->add_timestamp &= ~RB_ADD_STAMP_FORCE;
+ }
/*
* If this is the first commit on the page, then it has the same
* timestamp as the page itself.
*/
- if (!tail && !ring_buffer_time_stamp_abs(cpu_buffer->buffer))
+ if (unlikely(!tail && !(info->add_timestamp &
+ (RB_ADD_STAMP_FORCE | RB_ADD_STAMP_ABSOLUTE))))
info->delta = 0;
-
- /* See if we shot pass the end of this buffer page */
- if (unlikely(write > BUF_PAGE_SIZE))
- return rb_move_tail(cpu_buffer, tail, info);
/* We reserved something on the buffer */
@@ -2852,7 +3415,7 @@
* If this is the first commit on the page, then update
* its timestamp.
*/
- if (!tail)
+ if (unlikely(!tail))
tail_page->page->time_stamp = info->ts;
/* account for these added bytes */
@@ -2862,16 +3425,17 @@
}
static __always_inline struct ring_buffer_event *
-rb_reserve_next_event(struct ring_buffer *buffer,
+rb_reserve_next_event(struct trace_buffer *buffer,
struct ring_buffer_per_cpu *cpu_buffer,
unsigned long length)
{
struct ring_buffer_event *event;
struct rb_event_info info;
int nr_loops = 0;
- u64 diff;
+ int add_ts_default;
rb_start_commit(cpu_buffer);
+ /* The commit page can not change after this */
#ifdef CONFIG_RING_BUFFER_ALLOW_SWAP
/*
@@ -2889,8 +3453,16 @@
#endif
info.length = rb_calculate_event_length(length);
+
+ if (ring_buffer_time_stamp_abs(cpu_buffer->buffer)) {
+ add_ts_default = RB_ADD_STAMP_ABSOLUTE;
+ info.length += RB_LEN_TIME_EXTEND;
+ } else {
+ add_ts_default = RB_ADD_STAMP_NONE;
+ }
+
again:
- info.add_timestamp = 0;
+ info.add_timestamp = add_ts_default;
info.delta = 0;
/*
@@ -2905,35 +3477,16 @@
if (RB_WARN_ON(cpu_buffer, ++nr_loops > 1000))
goto out_fail;
- info.ts = rb_time_stamp(cpu_buffer->buffer);
- diff = info.ts - cpu_buffer->write_stamp;
-
- /* make sure this diff is calculated here */
- barrier();
-
- if (ring_buffer_time_stamp_abs(buffer)) {
- info.delta = info.ts;
- rb_handle_timestamp(cpu_buffer, &info);
- } else /* Did the write stamp get updated already? */
- if (likely(info.ts >= cpu_buffer->write_stamp)) {
- info.delta = diff;
- if (unlikely(test_time_stamp(info.delta)))
- rb_handle_timestamp(cpu_buffer, &info);
- }
-
event = __rb_reserve_next(cpu_buffer, &info);
if (unlikely(PTR_ERR(event) == -EAGAIN)) {
- if (info.add_timestamp)
+ if (info.add_timestamp & (RB_ADD_STAMP_FORCE | RB_ADD_STAMP_EXTEND))
info.length -= RB_LEN_TIME_EXTEND;
goto again;
}
- if (!event)
- goto out_fail;
-
- return event;
-
+ if (likely(event))
+ return event;
out_fail:
rb_end_commit(cpu_buffer);
return NULL;
@@ -2955,7 +3508,7 @@
* If NULL is returned, then nothing has been allocated or locked.
*/
struct ring_buffer_event *
-ring_buffer_lock_reserve(struct ring_buffer *buffer, unsigned long length)
+ring_buffer_lock_reserve(struct trace_buffer *buffer, unsigned long length)
{
struct ring_buffer_per_cpu *cpu_buffer;
struct ring_buffer_event *event;
@@ -3056,7 +3609,7 @@
* If this function is called, do not call ring_buffer_unlock_commit on
* the event.
*/
-void ring_buffer_discard_commit(struct ring_buffer *buffer,
+void ring_buffer_discard_commit(struct trace_buffer *buffer,
struct ring_buffer_event *event)
{
struct ring_buffer_per_cpu *cpu_buffer;
@@ -3079,11 +3632,6 @@
if (rb_try_to_discard(cpu_buffer, event))
goto out;
- /*
- * The commit is still visible by the reader, so we
- * must still update the timestamp.
- */
- rb_update_write_stamp(cpu_buffer, event);
out:
rb_end_commit(cpu_buffer);
@@ -3107,7 +3655,7 @@
* Note, like ring_buffer_lock_reserve, the length is the length of the data
* and not the length of the event which would hold the header.
*/
-int ring_buffer_write(struct ring_buffer *buffer,
+int ring_buffer_write(struct trace_buffer *buffer,
unsigned long length,
void *data)
{
@@ -3205,9 +3753,9 @@
* This prevents all writes to the buffer. Any attempt to write
* to the buffer after this will fail and return NULL.
*
- * The caller should call synchronize_sched() after this.
+ * The caller should call synchronize_rcu() after this.
*/
-void ring_buffer_record_disable(struct ring_buffer *buffer)
+void ring_buffer_record_disable(struct trace_buffer *buffer)
{
atomic_inc(&buffer->record_disabled);
}
@@ -3220,7 +3768,7 @@
* Note, multiple disables will need the same number of enables
* to truly enable the writing (much like preempt_disable).
*/
-void ring_buffer_record_enable(struct ring_buffer *buffer)
+void ring_buffer_record_enable(struct trace_buffer *buffer)
{
atomic_dec(&buffer->record_disabled);
}
@@ -3237,7 +3785,7 @@
* it works like an on/off switch, where as the disable() version
* must be paired with a enable().
*/
-void ring_buffer_record_off(struct ring_buffer *buffer)
+void ring_buffer_record_off(struct trace_buffer *buffer)
{
unsigned int rd;
unsigned int new_rd;
@@ -3260,7 +3808,7 @@
* it works like an on/off switch, where as the enable() version
* must be paired with a disable().
*/
-void ring_buffer_record_on(struct ring_buffer *buffer)
+void ring_buffer_record_on(struct trace_buffer *buffer)
{
unsigned int rd;
unsigned int new_rd;
@@ -3278,7 +3826,7 @@
*
* Returns true if the ring buffer is in a state that it accepts writes.
*/
-bool ring_buffer_record_is_on(struct ring_buffer *buffer)
+bool ring_buffer_record_is_on(struct trace_buffer *buffer)
{
return !atomic_read(&buffer->record_disabled);
}
@@ -3294,7 +3842,7 @@
* ring_buffer_record_disable(), as that is a temporary disabling of
* the ring buffer.
*/
-bool ring_buffer_record_is_set_on(struct ring_buffer *buffer)
+bool ring_buffer_record_is_set_on(struct trace_buffer *buffer)
{
return !(atomic_read(&buffer->record_disabled) & RB_BUFFER_OFF);
}
@@ -3307,9 +3855,9 @@
* This prevents all writes to the buffer. Any attempt to write
* to the buffer after this will fail and return NULL.
*
- * The caller should call synchronize_sched() after this.
+ * The caller should call synchronize_rcu() after this.
*/
-void ring_buffer_record_disable_cpu(struct ring_buffer *buffer, int cpu)
+void ring_buffer_record_disable_cpu(struct trace_buffer *buffer, int cpu)
{
struct ring_buffer_per_cpu *cpu_buffer;
@@ -3329,7 +3877,7 @@
* Note, multiple disables will need the same number of enables
* to truly enable the writing (much like preempt_disable).
*/
-void ring_buffer_record_enable_cpu(struct ring_buffer *buffer, int cpu)
+void ring_buffer_record_enable_cpu(struct trace_buffer *buffer, int cpu)
{
struct ring_buffer_per_cpu *cpu_buffer;
@@ -3359,7 +3907,7 @@
* @buffer: The ring buffer
* @cpu: The per CPU buffer to read from.
*/
-u64 ring_buffer_oldest_event_ts(struct ring_buffer *buffer, int cpu)
+u64 ring_buffer_oldest_event_ts(struct trace_buffer *buffer, int cpu)
{
unsigned long flags;
struct ring_buffer_per_cpu *cpu_buffer;
@@ -3388,11 +3936,11 @@
EXPORT_SYMBOL_GPL(ring_buffer_oldest_event_ts);
/**
- * ring_buffer_bytes_cpu - get the number of bytes consumed in a cpu buffer
+ * ring_buffer_bytes_cpu - get the number of bytes unconsumed in a cpu buffer
* @buffer: The ring buffer
* @cpu: The per CPU buffer to read from.
*/
-unsigned long ring_buffer_bytes_cpu(struct ring_buffer *buffer, int cpu)
+unsigned long ring_buffer_bytes_cpu(struct trace_buffer *buffer, int cpu)
{
struct ring_buffer_per_cpu *cpu_buffer;
unsigned long ret;
@@ -3412,7 +3960,7 @@
* @buffer: The ring buffer
* @cpu: The per CPU buffer to get the entries from.
*/
-unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu)
+unsigned long ring_buffer_entries_cpu(struct trace_buffer *buffer, int cpu)
{
struct ring_buffer_per_cpu *cpu_buffer;
@@ -3431,7 +3979,7 @@
* @buffer: The ring buffer
* @cpu: The per CPU buffer to get the number of overruns from
*/
-unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu)
+unsigned long ring_buffer_overrun_cpu(struct trace_buffer *buffer, int cpu)
{
struct ring_buffer_per_cpu *cpu_buffer;
unsigned long ret;
@@ -3454,7 +4002,7 @@
* @cpu: The per CPU buffer to get the number of overruns from
*/
unsigned long
-ring_buffer_commit_overrun_cpu(struct ring_buffer *buffer, int cpu)
+ring_buffer_commit_overrun_cpu(struct trace_buffer *buffer, int cpu)
{
struct ring_buffer_per_cpu *cpu_buffer;
unsigned long ret;
@@ -3476,7 +4024,7 @@
* @cpu: The per CPU buffer to get the number of overruns from
*/
unsigned long
-ring_buffer_dropped_events_cpu(struct ring_buffer *buffer, int cpu)
+ring_buffer_dropped_events_cpu(struct trace_buffer *buffer, int cpu)
{
struct ring_buffer_per_cpu *cpu_buffer;
unsigned long ret;
@@ -3497,7 +4045,7 @@
* @cpu: The per CPU buffer to get the number of events read
*/
unsigned long
-ring_buffer_read_events_cpu(struct ring_buffer *buffer, int cpu)
+ring_buffer_read_events_cpu(struct trace_buffer *buffer, int cpu)
{
struct ring_buffer_per_cpu *cpu_buffer;
@@ -3516,7 +4064,7 @@
* Returns the total number of entries in the ring buffer
* (all CPU entries)
*/
-unsigned long ring_buffer_entries(struct ring_buffer *buffer)
+unsigned long ring_buffer_entries(struct trace_buffer *buffer)
{
struct ring_buffer_per_cpu *cpu_buffer;
unsigned long entries = 0;
@@ -3539,7 +4087,7 @@
* Returns the total number of overruns in the ring buffer
* (all CPU entries)
*/
-unsigned long ring_buffer_overruns(struct ring_buffer *buffer)
+unsigned long ring_buffer_overruns(struct trace_buffer *buffer)
{
struct ring_buffer_per_cpu *cpu_buffer;
unsigned long overruns = 0;
@@ -3562,14 +4110,19 @@
/* Iterator usage is expected to have record disabled */
iter->head_page = cpu_buffer->reader_page;
iter->head = cpu_buffer->reader_page->read;
+ iter->next_event = iter->head;
iter->cache_reader_page = iter->head_page;
iter->cache_read = cpu_buffer->read;
+ iter->cache_pages_removed = cpu_buffer->pages_removed;
- if (iter->head)
+ if (iter->head) {
iter->read_stamp = cpu_buffer->read_stamp;
- else
+ iter->page_stamp = cpu_buffer->reader_page->page->time_stamp;
+ } else {
iter->read_stamp = iter->head_page->page->time_stamp;
+ iter->page_stamp = iter->read_stamp;
+ }
}
/**
@@ -3605,17 +4158,38 @@
struct buffer_page *reader;
struct buffer_page *head_page;
struct buffer_page *commit_page;
+ struct buffer_page *curr_commit_page;
unsigned commit;
+ u64 curr_commit_ts;
+ u64 commit_ts;
cpu_buffer = iter->cpu_buffer;
-
- /* Remember, trace recording is off when iterator is in use */
reader = cpu_buffer->reader_page;
head_page = cpu_buffer->head_page;
commit_page = cpu_buffer->commit_page;
- commit = rb_page_commit(commit_page);
+ commit_ts = commit_page->page->time_stamp;
- return ((iter->head_page == commit_page && iter->head == commit) ||
+ /*
+ * When the writer goes across pages, it issues a cmpxchg which
+ * is a mb(), which will synchronize with the rmb here.
+ * (see rb_tail_page_update())
+ */
+ smp_rmb();
+ commit = rb_page_commit(commit_page);
+ /* We want to make sure that the commit page doesn't change */
+ smp_rmb();
+
+ /* Make sure commit page didn't change */
+ curr_commit_page = READ_ONCE(cpu_buffer->commit_page);
+ curr_commit_ts = READ_ONCE(curr_commit_page->page->time_stamp);
+
+ /* If the commit page changed, then there's more data */
+ if (curr_commit_page != commit_page ||
+ curr_commit_ts != commit_ts)
+ return 0;
+
+ /* Still racy, as it may return a false positive, but that's OK */
+ return ((iter->head_page == commit_page && iter->head >= commit) ||
(iter->head_page == reader && commit_page == head_page &&
head_page->read == commit &&
iter->head == rb_page_commit(cpu_buffer->reader_page)));
@@ -3647,7 +4221,7 @@
return;
default:
- BUG();
+ RB_WARN_ON(cpu_buffer, 1);
}
return;
}
@@ -3677,7 +4251,7 @@
return;
default:
- BUG();
+ RB_WARN_ON(iter->cpu_buffer, 1);
}
return;
}
@@ -3786,12 +4360,14 @@
goto spin;
/*
- * Yeah! We succeeded in replacing the page.
+ * Yay! We succeeded in replacing the page.
*
* Now make the new head point back to the reader page.
*/
rb_list_head(reader->list.next)->prev = &cpu_buffer->reader_page->list;
rb_inc_page(cpu_buffer, &cpu_buffer->head_page);
+
+ local_inc(&cpu_buffer->pages_read);
/* Finally update the reader page to the new head */
cpu_buffer->reader_page = reader;
@@ -3811,6 +4387,38 @@
arch_spin_unlock(&cpu_buffer->lock);
local_irq_restore(flags);
+
+ /*
+ * The writer has preempt disable, wait for it. But not forever
+ * Although, 1 second is pretty much "forever"
+ */
+#define USECS_WAIT 1000000
+ for (nr_loops = 0; nr_loops < USECS_WAIT; nr_loops++) {
+ /* If the write is past the end of page, a writer is still updating it */
+ if (likely(!reader || rb_page_write(reader) <= BUF_PAGE_SIZE))
+ break;
+
+ udelay(1);
+
+ /* Get the latest version of the reader write value */
+ smp_rmb();
+ }
+
+ /* The writer is not moving forward? Something is wrong */
+ if (RB_WARN_ON(cpu_buffer, nr_loops == USECS_WAIT))
+ reader = NULL;
+
+ /*
+ * Make sure we see any padding after the write update
+ * (see rb_reset_tail()).
+ *
+ * In addition, a writer may be writing on the reader page
+ * if the page has not been fully filled, so the read barrier
+ * is also needed to make sure we see the content of what is
+ * committed by the writer (see rb_set_commit_to_write()).
+ */
+ smp_rmb();
+
return reader;
}
@@ -3836,20 +4444,28 @@
length = rb_event_length(event);
cpu_buffer->reader_page->read += length;
+ cpu_buffer->read_bytes += length;
}
static void rb_advance_iter(struct ring_buffer_iter *iter)
{
struct ring_buffer_per_cpu *cpu_buffer;
- struct ring_buffer_event *event;
- unsigned length;
cpu_buffer = iter->cpu_buffer;
+
+ /* If head == next_event then we need to jump to the next event */
+ if (iter->head == iter->next_event) {
+ /* If the event gets overwritten again, there's nothing to do */
+ if (rb_iter_head_event(iter) == NULL)
+ return;
+ }
+
+ iter->head = iter->next_event;
/*
* Check if we are at the end of the buffer.
*/
- if (iter->head >= rb_page_size(iter->head_page)) {
+ if (iter->next_event >= rb_page_size(iter->head_page)) {
/* discarded commits can make the page empty */
if (iter->head_page == cpu_buffer->commit_page)
return;
@@ -3857,27 +4473,7 @@
return;
}
- event = rb_iter_head_event(iter);
-
- length = rb_event_length(event);
-
- /*
- * This should not be called to advance the header if we are
- * at the tail of the buffer.
- */
- if (RB_WARN_ON(cpu_buffer,
- (iter->head_page == cpu_buffer->commit_page) &&
- (iter->head + length > rb_commit_index(cpu_buffer))))
- return;
-
- rb_update_iter_read_stamp(iter, event);
-
- iter->head += length;
-
- /* check for end of page padding */
- if ((iter->head >= rb_page_size(iter->head_page)) &&
- (iter->head_page != cpu_buffer->commit_page))
- rb_inc_iter(iter);
+ rb_update_iter_read_stamp(iter, iter->event);
}
static int rb_lost_events(struct ring_buffer_per_cpu *cpu_buffer)
@@ -3951,7 +4547,7 @@
return event;
default:
- BUG();
+ RB_WARN_ON(cpu_buffer, 1);
}
return NULL;
@@ -3961,7 +4557,7 @@
static struct ring_buffer_event *
rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts)
{
- struct ring_buffer *buffer;
+ struct trace_buffer *buffer;
struct ring_buffer_per_cpu *cpu_buffer;
struct ring_buffer_event *event;
int nr_loops = 0;
@@ -3973,12 +4569,13 @@
buffer = cpu_buffer->buffer;
/*
- * Check if someone performed a consuming read to
- * the buffer. A consuming read invalidates the iterator
- * and we need to reset the iterator in this case.
+ * Check if someone performed a consuming read to the buffer
+ * or removed some pages from the buffer. In these cases,
+ * iterator was invalidated and we need to reset it.
*/
if (unlikely(iter->cache_read != cpu_buffer->read ||
- iter->cache_reader_page != cpu_buffer->reader_page))
+ iter->cache_reader_page != cpu_buffer->reader_page ||
+ iter->cache_pages_removed != cpu_buffer->pages_removed))
rb_iter_reset(iter);
again:
@@ -3986,14 +4583,13 @@
return NULL;
/*
- * We repeat when a time extend is encountered or we hit
- * the end of the page. Since the time extend is always attached
- * to a data event, we should never loop more than three times.
- * Once for going to next page, once on time extend, and
- * finally once to get the event.
- * (We never hit the following condition more than thrice).
+ * As the writer can mess with what the iterator is trying
+ * to read, just give up if we fail to get an event after
+ * three tries. The iterator is not as reliable when reading
+ * the ring buffer with an active write as the consumer is.
+ * Do not warn if the three failures is reached.
*/
- if (RB_WARN_ON(cpu_buffer, ++nr_loops > 3))
+ if (++nr_loops > 3)
return NULL;
if (rb_per_cpu_empty(cpu_buffer))
@@ -4005,6 +4601,8 @@
}
event = rb_iter_head_event(iter);
+ if (!event)
+ goto again;
switch (event->type_len) {
case RINGBUF_TYPE_PADDING:
@@ -4039,7 +4637,7 @@
return event;
default:
- BUG();
+ RB_WARN_ON(cpu_buffer, 1);
}
return NULL;
@@ -4089,7 +4687,7 @@
* not consume the data.
*/
struct ring_buffer_event *
-ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts,
+ring_buffer_peek(struct trace_buffer *buffer, int cpu, u64 *ts,
unsigned long *lost_events)
{
struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu];
@@ -4114,6 +4712,20 @@
return event;
}
+
+/** ring_buffer_iter_dropped - report if there are dropped events
+ * @iter: The ring buffer iterator
+ *
+ * Returns true if there was dropped events since the last peek.
+ */
+bool ring_buffer_iter_dropped(struct ring_buffer_iter *iter)
+{
+ bool ret = iter->missed_events != 0;
+
+ iter->missed_events = 0;
+ return ret;
+}
+EXPORT_SYMBOL_GPL(ring_buffer_iter_dropped);
/**
* ring_buffer_iter_peek - peek at the next event to be read
@@ -4153,7 +4765,7 @@
* and eventually empty the ring buffer if the producer is slower.
*/
struct ring_buffer_event *
-ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts,
+ring_buffer_consume(struct trace_buffer *buffer, int cpu, u64 *ts,
unsigned long *lost_events)
{
struct ring_buffer_per_cpu *cpu_buffer;
@@ -4213,7 +4825,7 @@
* This overall must be paired with ring_buffer_read_finish.
*/
struct ring_buffer_iter *
-ring_buffer_read_prepare(struct ring_buffer *buffer, int cpu, gfp_t flags)
+ring_buffer_read_prepare(struct trace_buffer *buffer, int cpu, gfp_t flags)
{
struct ring_buffer_per_cpu *cpu_buffer;
struct ring_buffer_iter *iter;
@@ -4221,16 +4833,21 @@
if (!cpumask_test_cpu(cpu, buffer->cpumask))
return NULL;
- iter = kmalloc(sizeof(*iter), flags);
+ iter = kzalloc(sizeof(*iter), flags);
if (!iter)
return NULL;
+
+ iter->event = kmalloc(BUF_MAX_DATA_SIZE, flags);
+ if (!iter->event) {
+ kfree(iter);
+ return NULL;
+ }
cpu_buffer = buffer->buffers[cpu];
iter->cpu_buffer = cpu_buffer;
- atomic_inc(&buffer->resize_disabled);
- atomic_inc(&cpu_buffer->record_disabled);
+ atomic_inc(&cpu_buffer->resize_disabled);
return iter;
}
@@ -4246,7 +4863,7 @@
void
ring_buffer_read_prepare_sync(void)
{
- synchronize_sched();
+ synchronize_rcu();
}
EXPORT_SYMBOL_GPL(ring_buffer_read_prepare_sync);
@@ -4303,48 +4920,38 @@
rb_check_pages(cpu_buffer);
raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
- atomic_dec(&cpu_buffer->record_disabled);
- atomic_dec(&cpu_buffer->buffer->resize_disabled);
+ atomic_dec(&cpu_buffer->resize_disabled);
+ kfree(iter->event);
kfree(iter);
}
EXPORT_SYMBOL_GPL(ring_buffer_read_finish);
/**
- * ring_buffer_read - read the next item in the ring buffer by the iterator
+ * ring_buffer_iter_advance - advance the iterator to the next location
* @iter: The ring buffer iterator
- * @ts: The time stamp of the event read.
*
- * This reads the next event in the ring buffer and increments the iterator.
+ * Move the location of the iterator such that the next read will
+ * be the next location of the iterator.
*/
-struct ring_buffer_event *
-ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts)
+void ring_buffer_iter_advance(struct ring_buffer_iter *iter)
{
- struct ring_buffer_event *event;
struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer;
unsigned long flags;
raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags);
- again:
- event = rb_iter_peek(iter, ts);
- if (!event)
- goto out;
-
- if (event->type_len == RINGBUF_TYPE_PADDING)
- goto again;
rb_advance_iter(iter);
- out:
- raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
- return event;
+ raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
}
-EXPORT_SYMBOL_GPL(ring_buffer_read);
+EXPORT_SYMBOL_GPL(ring_buffer_iter_advance);
/**
* ring_buffer_size - return the size of the ring buffer (in bytes)
* @buffer: The ring buffer.
+ * @cpu: The CPU to get ring buffer size from.
*/
-unsigned long ring_buffer_size(struct ring_buffer *buffer, int cpu)
+unsigned long ring_buffer_size(struct trace_buffer *buffer, int cpu)
{
/*
* Earlier, this method returned
@@ -4359,28 +4966,34 @@
}
EXPORT_SYMBOL_GPL(ring_buffer_size);
+static void rb_clear_buffer_page(struct buffer_page *page)
+{
+ local_set(&page->write, 0);
+ local_set(&page->entries, 0);
+ rb_init_page(page->page);
+ page->read = 0;
+}
+
static void
rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer)
{
+ struct buffer_page *page;
+
rb_head_page_deactivate(cpu_buffer);
cpu_buffer->head_page
= list_entry(cpu_buffer->pages, struct buffer_page, list);
- local_set(&cpu_buffer->head_page->write, 0);
- local_set(&cpu_buffer->head_page->entries, 0);
- local_set(&cpu_buffer->head_page->page->commit, 0);
-
- cpu_buffer->head_page->read = 0;
+ rb_clear_buffer_page(cpu_buffer->head_page);
+ list_for_each_entry(page, cpu_buffer->pages, list) {
+ rb_clear_buffer_page(page);
+ }
cpu_buffer->tail_page = cpu_buffer->head_page;
cpu_buffer->commit_page = cpu_buffer->head_page;
INIT_LIST_HEAD(&cpu_buffer->reader_page->list);
INIT_LIST_HEAD(&cpu_buffer->new_pages);
- local_set(&cpu_buffer->reader_page->write, 0);
- local_set(&cpu_buffer->reader_page->entries, 0);
- local_set(&cpu_buffer->reader_page->page->commit, 0);
- cpu_buffer->reader_page->read = 0;
+ rb_clear_buffer_page(cpu_buffer->reader_page);
local_set(&cpu_buffer->entries_bytes, 0);
local_set(&cpu_buffer->overrun, 0);
@@ -4389,38 +5002,28 @@
local_set(&cpu_buffer->entries, 0);
local_set(&cpu_buffer->committing, 0);
local_set(&cpu_buffer->commits, 0);
+ local_set(&cpu_buffer->pages_touched, 0);
+ local_set(&cpu_buffer->pages_lost, 0);
+ local_set(&cpu_buffer->pages_read, 0);
+ cpu_buffer->last_pages_touch = 0;
+ cpu_buffer->shortest_full = 0;
cpu_buffer->read = 0;
cpu_buffer->read_bytes = 0;
- cpu_buffer->write_stamp = 0;
- cpu_buffer->read_stamp = 0;
+ rb_time_set(&cpu_buffer->write_stamp, 0);
+ rb_time_set(&cpu_buffer->before_stamp, 0);
cpu_buffer->lost_events = 0;
cpu_buffer->last_overrun = 0;
rb_head_page_activate(cpu_buffer);
+ cpu_buffer->pages_removed = 0;
}
-/**
- * ring_buffer_reset_cpu - reset a ring buffer per CPU buffer
- * @buffer: The ring buffer to reset a per cpu buffer of
- * @cpu: The CPU buffer to be reset
- */
-void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu)
+/* Must have disabled the cpu buffer then done a synchronize_rcu */
+static void reset_disabled_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer)
{
- struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu];
unsigned long flags;
-
- if (!cpumask_test_cpu(cpu, buffer->cpumask))
- return;
- /* prevent another thread from changing buffer sizes */
- mutex_lock(&buffer->mutex);
-
- atomic_inc(&buffer->resize_disabled);
- atomic_inc(&cpu_buffer->record_disabled);
-
- /* Make sure all commits have finished */
- synchronize_sched();
raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags);
@@ -4435,24 +5038,115 @@
out:
raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
+}
+
+/**
+ * ring_buffer_reset_cpu - reset a ring buffer per CPU buffer
+ * @buffer: The ring buffer to reset a per cpu buffer of
+ * @cpu: The CPU buffer to be reset
+ */
+void ring_buffer_reset_cpu(struct trace_buffer *buffer, int cpu)
+{
+ struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu];
+
+ if (!cpumask_test_cpu(cpu, buffer->cpumask))
+ return;
+
+ /* prevent another thread from changing buffer sizes */
+ mutex_lock(&buffer->mutex);
+
+ atomic_inc(&cpu_buffer->resize_disabled);
+ atomic_inc(&cpu_buffer->record_disabled);
+
+ /* Make sure all commits have finished */
+ synchronize_rcu();
+
+ reset_disabled_cpu_buffer(cpu_buffer);
atomic_dec(&cpu_buffer->record_disabled);
- atomic_dec(&buffer->resize_disabled);
+ atomic_dec(&cpu_buffer->resize_disabled);
mutex_unlock(&buffer->mutex);
}
EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu);
+/* Flag to ensure proper resetting of atomic variables */
+#define RESET_BIT (1 << 30)
+
+/**
+ * ring_buffer_reset_cpu - reset a ring buffer per CPU buffer
+ * @buffer: The ring buffer to reset a per cpu buffer of
+ * @cpu: The CPU buffer to be reset
+ */
+void ring_buffer_reset_online_cpus(struct trace_buffer *buffer)
+{
+ struct ring_buffer_per_cpu *cpu_buffer;
+ int cpu;
+
+ /* prevent another thread from changing buffer sizes */
+ mutex_lock(&buffer->mutex);
+
+ for_each_online_buffer_cpu(buffer, cpu) {
+ cpu_buffer = buffer->buffers[cpu];
+
+ atomic_add(RESET_BIT, &cpu_buffer->resize_disabled);
+ atomic_inc(&cpu_buffer->record_disabled);
+ }
+
+ /* Make sure all commits have finished */
+ synchronize_rcu();
+
+ for_each_buffer_cpu(buffer, cpu) {
+ cpu_buffer = buffer->buffers[cpu];
+
+ /*
+ * If a CPU came online during the synchronize_rcu(), then
+ * ignore it.
+ */
+ if (!(atomic_read(&cpu_buffer->resize_disabled) & RESET_BIT))
+ continue;
+
+ reset_disabled_cpu_buffer(cpu_buffer);
+
+ atomic_dec(&cpu_buffer->record_disabled);
+ atomic_sub(RESET_BIT, &cpu_buffer->resize_disabled);
+ }
+
+ mutex_unlock(&buffer->mutex);
+}
+
/**
* ring_buffer_reset - reset a ring buffer
* @buffer: The ring buffer to reset all cpu buffers
*/
-void ring_buffer_reset(struct ring_buffer *buffer)
+void ring_buffer_reset(struct trace_buffer *buffer)
{
+ struct ring_buffer_per_cpu *cpu_buffer;
int cpu;
- for_each_buffer_cpu(buffer, cpu)
- ring_buffer_reset_cpu(buffer, cpu);
+ /* prevent another thread from changing buffer sizes */
+ mutex_lock(&buffer->mutex);
+
+ for_each_buffer_cpu(buffer, cpu) {
+ cpu_buffer = buffer->buffers[cpu];
+
+ atomic_inc(&cpu_buffer->resize_disabled);
+ atomic_inc(&cpu_buffer->record_disabled);
+ }
+
+ /* Make sure all commits have finished */
+ synchronize_rcu();
+
+ for_each_buffer_cpu(buffer, cpu) {
+ cpu_buffer = buffer->buffers[cpu];
+
+ reset_disabled_cpu_buffer(cpu_buffer);
+
+ atomic_dec(&cpu_buffer->record_disabled);
+ atomic_dec(&cpu_buffer->resize_disabled);
+ }
+
+ mutex_unlock(&buffer->mutex);
}
EXPORT_SYMBOL_GPL(ring_buffer_reset);
@@ -4460,7 +5154,7 @@
* rind_buffer_empty - is the ring buffer empty?
* @buffer: The ring buffer to test
*/
-bool ring_buffer_empty(struct ring_buffer *buffer)
+bool ring_buffer_empty(struct trace_buffer *buffer)
{
struct ring_buffer_per_cpu *cpu_buffer;
unsigned long flags;
@@ -4490,7 +5184,7 @@
* @buffer: The ring buffer
* @cpu: The CPU buffer to test
*/
-bool ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu)
+bool ring_buffer_empty_cpu(struct trace_buffer *buffer, int cpu)
{
struct ring_buffer_per_cpu *cpu_buffer;
unsigned long flags;
@@ -4516,14 +5210,15 @@
* ring_buffer_swap_cpu - swap a CPU buffer between two ring buffers
* @buffer_a: One buffer to swap with
* @buffer_b: The other buffer to swap with
+ * @cpu: the CPU of the buffers to swap
*
* This function is useful for tracers that want to take a "snapshot"
* of a CPU buffer and has another back up buffer lying around.
* it is expected that the tracer handles the cpu buffer not being
* used at the moment.
*/
-int ring_buffer_swap_cpu(struct ring_buffer *buffer_a,
- struct ring_buffer *buffer_b, int cpu)
+int ring_buffer_swap_cpu(struct trace_buffer *buffer_a,
+ struct trace_buffer *buffer_b, int cpu)
{
struct ring_buffer_per_cpu *cpu_buffer_a;
struct ring_buffer_per_cpu *cpu_buffer_b;
@@ -4555,7 +5250,7 @@
goto out;
/*
- * We can't do a synchronize_sched here because this
+ * We can't do a synchronize_rcu here because this
* function can be called in atomic context.
* Normally this will be called from the same CPU as cpu.
* If not it's up to the caller to protect this.
@@ -4567,6 +5262,15 @@
if (local_read(&cpu_buffer_a->committing))
goto out_dec;
if (local_read(&cpu_buffer_b->committing))
+ goto out_dec;
+
+ /*
+ * When resize is in progress, we cannot swap it because
+ * it will mess the state of the cpu buffer.
+ */
+ if (atomic_read(&buffer_a->resizing))
+ goto out_dec;
+ if (atomic_read(&buffer_b->resizing))
goto out_dec;
buffer_a->buffers[cpu] = cpu_buffer_b;
@@ -4602,7 +5306,7 @@
* Returns:
* The page allocated, or ERR_PTR
*/
-void *ring_buffer_alloc_read_page(struct ring_buffer *buffer, int cpu)
+void *ring_buffer_alloc_read_page(struct trace_buffer *buffer, int cpu)
{
struct ring_buffer_per_cpu *cpu_buffer;
struct buffer_data_page *bpage = NULL;
@@ -4649,12 +5353,17 @@
*
* Free a page allocated from ring_buffer_alloc_read_page.
*/
-void ring_buffer_free_read_page(struct ring_buffer *buffer, int cpu, void *data)
+void ring_buffer_free_read_page(struct trace_buffer *buffer, int cpu, void *data)
{
- struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu];
+ struct ring_buffer_per_cpu *cpu_buffer;
struct buffer_data_page *bpage = data;
struct page *page = virt_to_page(bpage);
unsigned long flags;
+
+ if (!buffer || !buffer->buffers || !buffer->buffers[cpu])
+ return;
+
+ cpu_buffer = buffer->buffers[cpu];
/* If the page is still in use someplace else, we can't reuse it */
if (page_ref_count(page) > 1)
@@ -4709,7 +5418,7 @@
* >=0 if data has been transferred, returns the offset of consumed data.
* <0 if no data has been transferred.
*/
-int ring_buffer_read_page(struct ring_buffer *buffer,
+int ring_buffer_read_page(struct trace_buffer *buffer,
void **data_page, size_t len, int cpu, int full)
{
struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu];
@@ -4770,7 +5479,15 @@
unsigned int pos = 0;
unsigned int size;
- if (full)
+ /*
+ * If a full page is expected, this can still be returned
+ * if there's been a previous partial read and the
+ * rest of the page can be read and the commit page is off
+ * the reader page.
+ */
+ if (full &&
+ (!read || (len < (commit - read)) ||
+ cpu_buffer->reader_page == cpu_buffer->commit_page))
goto out_unlock;
if (len > (commit - read))
@@ -4819,7 +5536,7 @@
} else {
/* update the entry counter */
cpu_buffer->read += rb_page_entries(reader);
- cpu_buffer->read_bytes += BUF_PAGE_SIZE;
+ cpu_buffer->read_bytes += rb_page_commit(reader);
/* swap the pages */
rb_init_page(bpage);
@@ -4880,12 +5597,12 @@
*/
int trace_rb_cpu_prepare(unsigned int cpu, struct hlist_node *node)
{
- struct ring_buffer *buffer;
+ struct trace_buffer *buffer;
long nr_pages_same;
int cpu_i;
unsigned long nr_pages;
- buffer = container_of(node, struct ring_buffer, node);
+ buffer = container_of(node, struct trace_buffer, node);
if (cpumask_test_cpu(cpu, buffer->cpumask))
return 0;
@@ -4935,7 +5652,7 @@
static struct task_struct *rb_threads[NR_CPUS] __initdata;
struct rb_test_data {
- struct ring_buffer *buffer;
+ struct trace_buffer *buffer;
unsigned long events;
unsigned long bytes_written;
unsigned long bytes_alloc;
@@ -4983,7 +5700,7 @@
cnt = data->cnt + (nested ? 27 : 0);
/* Multiply cnt by ~e, to make some unique increment */
- size = (data->cnt * 68 / 25) % (sizeof(rb_string) - 1);
+ size = (cnt * 68 / 25) % (sizeof(rb_string) - 1);
len = size + sizeof(struct rb_item);
@@ -5077,10 +5794,15 @@
static __init int test_ringbuffer(void)
{
struct task_struct *rb_hammer;
- struct ring_buffer *buffer;
+ struct trace_buffer *buffer;
int cpu;
int ret = 0;
+ if (security_locked_down(LOCKDOWN_TRACEFS)) {
+ pr_warn("Lockdown is enabled, skipping ring buffer tests\n");
+ return 0;
+ }
+
pr_info("Running ring buffer tests...\n");
buffer = ring_buffer_alloc(RB_TEST_BUFFER_SIZE, RB_FL_OVERWRITE);
--
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