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[PATCH] copy_process: cleanup bad_fork_cleanup_signal

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__exit_signal() does important cleanups atomically under ->siglock.  It is
also called from copy_process's error path.  This is not good, for example we
can't move __unhash_process() under ->siglock for that reason.

We should not mix these 2 paths, just look at ugly 'if (p->sighand)' under
'bad_fork_cleanup_sighand:' label.  For copy_process() case it is sufficient
to just backout copy_signal(), nothing more.

Again, nobody can see this task yet.  For CLONE_THREAD case we just decrement
signal->count, otherwise nobody can see this ->signal and we can free it
lockless.

This patch assumes it is safe to do exit_thread_group_keys() without
tasklist_lock.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Oleg Nesterov 2006-03-28 16:11:16 -08:00 • committed by Linus Torvalds
parent 7001510d0c
commit 6b3934ef52
4 changed files with 21 additions and 20 deletions
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15
kernel/signal.c
View file

@ -395,23 +395,10 @@ void __exit_signal(struct task_struct *tsk)
clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
flush_sigqueue(&tsk->pending);
if (sig) {
/*
* We are cleaning up the signal_struct here.
*/
exit_thread_group_keys(sig);
kmem_cache_free(signal_cachep, sig);
__cleanup_signal(sig);
}
}
void exit_signal(struct task_struct *tsk)
{
atomic_dec(&tsk->signal->live);
write_lock_irq(&tasklist_lock);
__exit_signal(tsk);
write_unlock_irq(&tasklist_lock);
}
/*
* Flush all handlers for a task.
*/