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| author | Roland McGrath <roland@redhat.com> | 2005-10-21 15:03:29 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2005-10-21 15:38:08 -0700 |
| commit | 25f407f0b668f5e4ebd5d13e1fb4306ba6427ead (patch) | |
| tree | 10d8661419da9e0d6be6d22ef319582d052c4a26 | |
| parent | 9465bee863bc4c6cf1566c12d6f92a8133e3da5c (diff) | |
| download | lwn-25f407f0b668f5e4ebd5d13e1fb4306ba6427ead.tar.gz lwn-25f407f0b668f5e4ebd5d13e1fb4306ba6427ead.zip | |
[PATCH] Call exit_itimers from do_exit, not __exit_signal
When I originally moved exit_itimers into __exit_signal, that was the only
place where we could reliably know it was the last thread in the group
dying, without races. Since then we've gotten the signal_struct.live
counter, and do_exit can reliably do group-wide cleanup work.
This patch moves the call to do_exit, where it's made without locks. This
avoids the deadlock issues that the old __exit_signal code's comment talks
about, and the one that Oleg found recently with process CPU timers.
[ This replaces e03d13e985d48ac4885382c9e3b1510c78bd047f, which is why
it was just reverted. ]
Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
| -rw-r--r-- | kernel/exit.c | 1 | ||||
| -rw-r--r-- | kernel/posix-timers.c | 2 | ||||
| -rw-r--r-- | kernel/signal.c | 14 |
3 files changed, 3 insertions, 14 deletions
diff --git a/kernel/exit.c b/kernel/exit.c index 43077732619b..3b25b182d2be 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -843,6 +843,7 @@ fastcall NORET_TYPE void do_exit(long code) group_dead = atomic_dec_and_test(&tsk->signal->live); if (group_dead) { del_timer_sync(&tsk->signal->real_timer); + exit_itimers(tsk->signal); acct_process(code); } exit_mm(tsk); diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c index b7b532acd9fc..dda3cda73c77 100644 --- a/kernel/posix-timers.c +++ b/kernel/posix-timers.c @@ -1157,7 +1157,7 @@ retry_delete: } /* - * This is called by __exit_signal, only when there are no more + * This is called by do_exit or de_thread, only when there are no more * references to the shared signal_struct. */ void exit_itimers(struct signal_struct *sig) diff --git a/kernel/signal.c b/kernel/signal.c index 50c992643771..f2b96b08fb44 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -397,20 +397,8 @@ void __exit_signal(struct task_struct *tsk) flush_sigqueue(&tsk->pending); if (sig) { /* - * We are cleaning up the signal_struct here. We delayed - * calling exit_itimers until after flush_sigqueue, just in - * case our thread-local pending queue contained a queued - * timer signal that would have been cleared in - * exit_itimers. When that called sigqueue_free, it would - * attempt to re-take the tasklist_lock and deadlock. This - * can never happen if we ensure that all queues the - * timer's signal might be queued on have been flushed - * first. The shared_pending queue, and our own pending - * queue are the only queues the timer could be on, since - * there are no other threads left in the group and timer - * signals are constrained to threads inside the group. + * We are cleaning up the signal_struct here. */ - exit_itimers(sig); exit_thread_group_keys(sig); kmem_cache_free(signal_cachep, sig); } |