diff options
author | Oleg Nesterov <oleg@tv-sign.ru> | 2005-10-24 14:34:03 +0400 |
---|---|---|
committer | Linus Torvalds <torvalds@g5.osdl.org> | 2005-10-24 19:12:35 +0400 |
commit | 3de463c7d9d58f8cf3395268230cb20a4c15bffa (patch) | |
tree | 20ba1584eefb7ed75f6f8536f40e55966294cf4f /kernel/posix-cpu-timers.c | |
parent | 108150ea78003044e41150c75259447b2c0953b6 (diff) | |
download | linux-3de463c7d9d58f8cf3395268230cb20a4c15bffa.tar.xz |
[PATCH] posix-timers: remove false BUG_ON() from run_posix_cpu_timers()
do_exit() clears ->it_##clock##_expires, but nothing prevents
another cpu to attach the timer to exiting process after that.
After exit_notify() does 'write_unlock_irq(&tasklist_lock)' and
before do_exit() calls 'schedule() local timer interrupt can find
tsk->exit_state != 0. If that state was EXIT_DEAD (or another cpu
does sys_wait4) interrupted task has ->signal == NULL.
At this moment exiting task has no pending cpu timers, they were cleaned
up in __exit_signal()->posix_cpu_timers_exit{,_group}(), so we can just
return from irq.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'kernel/posix-cpu-timers.c')
-rw-r--r-- | kernel/posix-cpu-timers.c | 36 |
1 files changed, 18 insertions, 18 deletions
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c index 30ab39a27736..ccb04683bf18 100644 --- a/kernel/posix-cpu-timers.c +++ b/kernel/posix-cpu-timers.c @@ -1285,30 +1285,30 @@ void run_posix_cpu_timers(struct task_struct *tsk) #undef UNEXPIRED - BUG_ON(tsk->exit_state); - /* * Double-check with locks held. */ read_lock(&tasklist_lock); - spin_lock(&tsk->sighand->siglock); + if (likely(tsk->signal != NULL)) { + spin_lock(&tsk->sighand->siglock); - /* - * Here we take off tsk->cpu_timers[N] and tsk->signal->cpu_timers[N] - * all the timers that are firing, and put them on the firing list. - */ - check_thread_timers(tsk, &firing); - check_process_timers(tsk, &firing); + /* + * Here we take off tsk->cpu_timers[N] and tsk->signal->cpu_timers[N] + * all the timers that are firing, and put them on the firing list. + */ + check_thread_timers(tsk, &firing); + check_process_timers(tsk, &firing); - /* - * We must release these locks before taking any timer's lock. - * There is a potential race with timer deletion here, as the - * siglock now protects our private firing list. We have set - * the firing flag in each timer, so that a deletion attempt - * that gets the timer lock before we do will give it up and - * spin until we've taken care of that timer below. - */ - spin_unlock(&tsk->sighand->siglock); + /* + * We must release these locks before taking any timer's lock. + * There is a potential race with timer deletion here, as the + * siglock now protects our private firing list. We have set + * the firing flag in each timer, so that a deletion attempt + * that gets the timer lock before we do will give it up and + * spin until we've taken care of that timer below. + */ + spin_unlock(&tsk->sighand->siglock); + } read_unlock(&tasklist_lock); /* |