mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-22 17:01:14 +00:00
sched: fix TASK_WAKEKILL vs SIGKILL race
schedule() has the special "TASK_INTERRUPTIBLE && signal_pending()" case, this allows us to do current->state = TASK_INTERRUPTIBLE; schedule(); without fear to sleep with pending signal. However, the code like current->state = TASK_KILLABLE; schedule(); is not right, schedule() doesn't take TASK_WAKEKILL into account. This means that mutex_lock_killable(), wait_for_completion_killable(), down_killable(), schedule_timeout_killable() can miss SIGKILL (and btw the second SIGKILL has no effect). Introduce the new helper, signal_pending_state(), and change schedule() to use it. Hopefully it will have more users, that is why the task's state is passed separately. Note this "__TASK_STOPPED | __TASK_TRACED" check in signal_pending_state(). This is needed to preserve the current behaviour (ptrace_notify). I hope this check will be removed soon, but this (afaics good) change needs the separate discussion. The fast path is "(state & (INTERRUPTIBLE | WAKEKILL)) + signal_pending(p)", basically the same that schedule() does now. However, this patch of course bloats schedule(). Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
parent
39b945a37b
commit
16882c1e96
2 changed files with 15 additions and 4 deletions
|
@ -2026,6 +2026,19 @@ static inline int fatal_signal_pending(struct task_struct *p)
|
|||
return signal_pending(p) && __fatal_signal_pending(p);
|
||||
}
|
||||
|
||||
static inline int signal_pending_state(long state, struct task_struct *p)
|
||||
{
|
||||
if (!(state & (TASK_INTERRUPTIBLE | TASK_WAKEKILL)))
|
||||
return 0;
|
||||
if (!signal_pending(p))
|
||||
return 0;
|
||||
|
||||
if (state & (__TASK_STOPPED | __TASK_TRACED))
|
||||
return 0;
|
||||
|
||||
return (state & TASK_INTERRUPTIBLE) || __fatal_signal_pending(p);
|
||||
}
|
||||
|
||||
static inline int need_resched(void)
|
||||
{
|
||||
return unlikely(test_thread_flag(TIF_NEED_RESCHED));
|
||||
|
|
|
@ -4159,12 +4159,10 @@ asmlinkage void __sched schedule(void)
|
|||
clear_tsk_need_resched(prev);
|
||||
|
||||
if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
|
||||
if (unlikely((prev->state & TASK_INTERRUPTIBLE) &&
|
||||
signal_pending(prev))) {
|
||||
if (unlikely(signal_pending_state(prev->state, prev)))
|
||||
prev->state = TASK_RUNNING;
|
||||
} else {
|
||||
else
|
||||
deactivate_task(rq, prev, 1);
|
||||
}
|
||||
switch_count = &prev->nvcsw;
|
||||
}
|
||||
|
||||
|
|
Loading…
Reference in a new issue