Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932616AbWBTOqm (ORCPT ); Mon, 20 Feb 2006 09:46:42 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932537AbWBTOql (ORCPT ); Mon, 20 Feb 2006 09:46:41 -0500 Received: from mail.tv-sign.ru ([213.234.233.51]:49362 "EHLO several.ru") by vger.kernel.org with ESMTP id S932616AbWBTOqa (ORCPT ); Mon, 20 Feb 2006 09:46:30 -0500 Message-ID: <43F9E85E.4D7C2967@tv-sign.ru> Date: Mon, 20 Feb 2006 19:03:42 +0300 From: Oleg Nesterov X-Mailer: Mozilla 4.76 [en] (X11; U; Linux 2.2.20 i686) X-Accept-Language: en MIME-Version: 1.0 To: Andrew Morton Cc: linux-kernel@vger.kernel.org, Ingo Molnar , "Paul E. McKenney" , "Eric W. Biederman" , Roland McGrath Subject: [PATCH 2/2] copy_process: cleanup bad_fork_cleanup_signal Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3156 Lines: 99 __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 --- 2.6.16-rc3/include/linux/sched.h~2_SGNL 2006-02-20 00:38:57.000000000 +0300 +++ 2.6.16-rc3/include/linux/sched.h 2006-02-20 02:01:27.000000000 +0300 @@ -1141,7 +1141,7 @@ extern void flush_thread(void); extern void exit_thread(void); extern void exit_files(struct task_struct *); -extern void exit_signal(struct task_struct *); +extern void __cleanup_signal(struct signal_struct *); extern void __exit_signal(struct task_struct *); extern void __exit_sighand(struct task_struct *); extern void exit_itimers(struct signal_struct *); --- 2.6.16-rc3/kernel/fork.c~2_SGNL 2006-02-20 00:38:39.000000000 +0300 +++ 2.6.16-rc3/kernel/fork.c 2006-02-20 02:02:38.000000000 +0300 @@ -870,6 +870,22 @@ static inline int copy_signal(unsigned l return 0; } +void __cleanup_signal(struct signal_struct *sig) +{ + exit_thread_group_keys(sig); + kmem_cache_free(signal_cachep, sig); +} + +static inline void cleanup_signal(struct task_struct *tsk) +{ + struct signal_struct *sig = tsk->signal; + + atomic_dec(&sig->live); + + if (atomic_dec_and_test(&sig->count)) + __cleanup_signal(sig); +} + static inline void copy_flags(unsigned long clone_flags, struct task_struct *p) { unsigned long new_flags = p->flags; @@ -1194,10 +1210,9 @@ bad_fork_cleanup_mm: if (p->mm) mmput(p->mm); bad_fork_cleanup_signal: - exit_signal(p); + cleanup_signal(p); bad_fork_cleanup_sighand: - if (p->sighand) - __exit_sighand(p); + __exit_sighand(p); bad_fork_cleanup_fs: exit_fs(p); /* blocking */ bad_fork_cleanup_files: --- 2.6.16-rc3/kernel/signal.c~2_SGNL 2006-02-20 00:37:34.000000000 +0300 +++ 2.6.16-rc3/kernel/signal.c 2006-02-20 02:02:03.000000000 +0300 @@ -395,23 +395,10 @@ void __exit_signal(struct task_struct *t 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. */ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/