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authorOleg Nesterov <oleg@tv-sign.ru>2006-06-15 20:11:43 +0400
committerLinus Torvalds <torvalds@g5.osdl.org>2006-06-17 10:52:13 -0700
commit30f1e3dd8c72abda343bcf415f7d8894a02b4290 (patch)
tree68ef326814e3b8e6ba0159cc451cef4b71695ea3 /kernel/exit.c
parent[PATCH] check_process_timers: fix possible lockup (diff)
downloadlinux-dev-30f1e3dd8c72abda343bcf415f7d8894a02b4290.tar.xz
linux-dev-30f1e3dd8c72abda343bcf415f7d8894a02b4290.zip
[PATCH] run_posix_cpu_timers: remove a bogus BUG_ON()
do_exit() clears ->it_##clock##_expires, but nothing prevents another cpu to attach the timer to exiting process after that. arm_timer() tries to protect against this race, but the check is racy. 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 cleanuped in __exit_signal()->posix_cpu_timers_exit{,_group}(), so we can just return from irq. John Stultz recently confirmed this bug, see http://marc.theaimsgroup.com/?l=linux-kernel&m=115015841413687 Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'kernel/exit.c')
-rw-r--r--kernel/exit.c8
1 files changed, 0 insertions, 8 deletions
diff --git a/kernel/exit.c b/kernel/exit.c
index e95b93282210..e06d0c10a24e 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -881,14 +881,6 @@ fastcall NORET_TYPE void do_exit(long code)
tsk->flags |= PF_EXITING;
- /*
- * Make sure we don't try to process any timer firings
- * while we are already exiting.
- */
- tsk->it_virt_expires = cputime_zero;
- tsk->it_prof_expires = cputime_zero;
- tsk->it_sched_expires = 0;
-
if (unlikely(in_atomic()))
printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
current->comm, current->pid,