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/signal.c | 105 ++++++----------------------------------------------
1 files changed, 12 insertions(+), 93 deletions(-)
diff --git a/kernel/kernel/signal.c b/kernel/kernel/signal.c
index e302702..f6ecd01 100644
--- a/kernel/kernel/signal.c
+++ b/kernel/kernel/signal.c
@@ -20,7 +20,6 @@
#include <linux/sched/task.h>
#include <linux/sched/task_stack.h>
#include <linux/sched/cputime.h>
-#include <linux/sched/rt.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/proc_fs.h>
@@ -408,30 +407,13 @@
task_set_jobctl_pending(task, mask | JOBCTL_STOP_PENDING);
}
-static inline struct sigqueue *get_task_cache(struct task_struct *t)
-{
- struct sigqueue *q = t->sigqueue_cache;
-
- if (cmpxchg(&t->sigqueue_cache, q, NULL) != q)
- return NULL;
- return q;
-}
-
-static inline int put_task_cache(struct task_struct *t, struct sigqueue *q)
-{
- if (cmpxchg(&t->sigqueue_cache, NULL, q) == NULL)
- return 0;
- return 1;
-}
-
/*
* allocate a new signal queue record
* - this may be called without locks if and only if t == current, otherwise an
* appropriate lock must be held to stop the target task from exiting
*/
static struct sigqueue *
-__sigqueue_do_alloc(int sig, struct task_struct *t, gfp_t flags,
- int override_rlimit, int fromslab)
+__sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
{
struct sigqueue *q = NULL;
struct user_struct *user;
@@ -453,10 +435,7 @@
rcu_read_unlock();
if (override_rlimit || likely(sigpending <= task_rlimit(t, RLIMIT_SIGPENDING))) {
- if (!fromslab)
- q = get_task_cache(t);
- if (!q)
- q = kmem_cache_alloc(sigqueue_cachep, flags);
+ q = kmem_cache_alloc(sigqueue_cachep, flags);
} else {
print_dropped_signal(sig);
}
@@ -473,13 +452,6 @@
return q;
}
-static struct sigqueue *
-__sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags,
- int override_rlimit)
-{
- return __sigqueue_do_alloc(sig, t, flags, override_rlimit, 0);
-}
-
static void __sigqueue_free(struct sigqueue *q)
{
if (q->flags & SIGQUEUE_PREALLOC)
@@ -487,21 +459,6 @@
if (atomic_dec_and_test(&q->user->sigpending))
free_uid(q->user);
kmem_cache_free(sigqueue_cachep, q);
-}
-
-static void sigqueue_free_current(struct sigqueue *q)
-{
- struct user_struct *up;
-
- if (q->flags & SIGQUEUE_PREALLOC)
- return;
-
- up = q->user;
- if (rt_prio(current->normal_prio) && !put_task_cache(current, q)) {
- if (atomic_dec_and_test(&up->sigpending))
- free_uid(up);
- } else
- __sigqueue_free(q);
}
void flush_sigqueue(struct sigpending *queue)
@@ -514,21 +471,6 @@
list_del_init(&q->list);
__sigqueue_free(q);
}
-}
-
-/*
- * Called from __exit_signal. Flush tsk->pending and
- * tsk->sigqueue_cache
- */
-void flush_task_sigqueue(struct task_struct *tsk)
-{
- struct sigqueue *q;
-
- flush_sigqueue(&tsk->pending);
-
- q = get_task_cache(tsk);
- if (q)
- kmem_cache_free(sigqueue_cachep, q);
}
/*
@@ -655,7 +597,7 @@
(info->si_code == SI_TIMER) &&
(info->si_sys_private);
- sigqueue_free_current(first);
+ __sigqueue_free(first);
} else {
/*
* Ok, it wasn't in the queue. This must be
@@ -691,8 +633,6 @@
{
bool resched_timer = false;
int signr;
-
- WARN_ON_ONCE(tsk != current);
/* We only dequeue private signals from ourselves, we don't let
* signalfd steal them
@@ -1377,34 +1317,6 @@
struct k_sigaction *action;
int sig = info->si_signo;
- /*
- * On some archs, PREEMPT_RT has to delay sending a signal from a trap
- * since it can not enable preemption, and the signal code's spin_locks
- * turn into mutexes. Instead, it must set TIF_NOTIFY_RESUME which will
- * send the signal on exit of the trap.
- */
-#ifdef ARCH_RT_DELAYS_SIGNAL_SEND
- if (in_atomic()) {
- struct task_struct *t = current;
-
- if (WARN_ON_ONCE(t->forced_info.si_signo))
- return 0;
-
- if (is_si_special(info)) {
- WARN_ON_ONCE(info != SEND_SIG_PRIV);
- t->forced_info.si_signo = info->si_signo;
- t->forced_info.si_errno = 0;
- t->forced_info.si_code = SI_KERNEL;
- t->forced_info.si_pid = 0;
- t->forced_info.si_uid = 0;
- } else {
- t->forced_info = *info;
- }
-
- set_tsk_thread_flag(t, TIF_NOTIFY_RESUME);
- return 0;
- }
-#endif
spin_lock_irqsave(&t->sighand->siglock, flags);
action = &t->sighand->action[sig-1];
ignored = action->sa.sa_handler == SIG_IGN;
@@ -1907,8 +1819,7 @@
*/
struct sigqueue *sigqueue_alloc(void)
{
- /* Preallocated sigqueue objects always from the slabcache ! */
- struct sigqueue *q = __sigqueue_do_alloc(-1, current, GFP_KERNEL, 0, 1);
+ struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
if (q)
q->flags |= SIGQUEUE_PREALLOC;
@@ -2294,8 +2205,16 @@
if (gstop_done && ptrace_reparented(current))
do_notify_parent_cldstop(current, false, why);
+ /*
+ * Don't want to allow preemption here, because
+ * sys_ptrace() needs this task to be inactive.
+ *
+ * XXX: implement read_unlock_no_resched().
+ */
+ preempt_disable();
read_unlock(&tasklist_lock);
cgroup_enter_frozen();
+ preempt_enable_no_resched();
freezable_schedule();
cgroup_leave_frozen(true);
} else {
--
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