Messages in this thread Patch in this message | | | Subject | [RFC, 2.6.26.2-rc1] posix timers: release_posix_timer: kill the bogus put_task_struct(->it_process) | Date | Sat, 2 Aug 2008 23:45:20 +0200 | From | Oliver Pinter <> |
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It is an RFC for sending this patch for stable, when this patch needed, then send ACK and CC stable, if not then send NAK.
--- From 96347e7759e2e433c427defa0fa1adfc8cce6226 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov <oleg@tv-sign.ru> Date: Fri, 25 Jul 2008 01:47:27 -0700 Subject: [PATCH] posix timers: release_posix_timer: kill the bogus put_task_struct(->it_process);
[ Upstream commit 96347e7759e2e433c427defa0fa1adfc8cce6226 ]
release_posix_timer() can't be called with ->it_process != NULL. Once sys_timer_create() sets ->it_process it must not call release_posix_timer(), otherwise we can race with another thread doing sys_timer_delete(), this timer is visible to idr_find() and unlocked.
The same is true for two other callers (actually, for any possible caller), sys_timer_delete() and itimer_delete(). They must clear ->it_process before unlock_timer() + release_posix_timer().
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Acked-by: Roland McGrath <roland@redhat.com> Cc: john stultz <johnstul@us.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Roland McGrath <roland@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> CC: Oliver Pinter <oliver.pntr@gmail.com>
diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c index 17f5326..9a21681 100644 --- a/kernel/posix-timers.c +++ b/kernel/posix-timers.c @@ -449,9 +449,6 @@ static void release_posix_timer(struct k_itimer *tmr, int it_id_set) spin_unlock_irqrestore(&idr_lock, flags); } sigqueue_free(tmr->sigq); - if (unlikely(tmr->it_process) && - tmr->it_sigev_notify == (SIGEV_SIGNAL|SIGEV_THREAD_ID)) - put_task_struct(tmr->it_process); kmem_cache_free(posix_timers_cache, tmr); }
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