Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754082AbYGaJEs (ORCPT ); Thu, 31 Jul 2008 05:04:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752499AbYGaJEj (ORCPT ); Thu, 31 Jul 2008 05:04:39 -0400 Received: from mx1.redhat.com ([66.187.233.31]:45781 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752496AbYGaJEi (ORCPT ); Thu, 31 Jul 2008 05:04:38 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit From: Roland McGrath To: Andrew Morton , Linus Torvalds Cc: Ulrich Drepper , linux-kernel@vger.kernel.org Subject: [PATCH] tracehook: fix exit_signal=0 case X-fcc: ~/Mail/linus X-windows: it could happen to you. Message-Id: <20080731090409.8D32A154263@magilla.localdomain> Date: Thu, 31 Jul 2008 02:04:09 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4463 Lines: 102 My commit 2b2a1ff64afbadac842bbc58c5166962cf4f7664 introduced a regression (sorry about that) for the odd case of exit_signal=0 (e.g. clone_flags=0). This is not a normal use, but it's used by a case in the glibc test suite. Dying with exit_signal=0 sends no signal, but it's supposed to wake up a parent's blocked wait*() calls (unlike the delayed_group_leader case). This fixes tracehook_notify_death() and its caller to distinguish a "signal 0" wakeup from the delayed_group_leader case (with no wakeup). Signed-off-by: Roland McGrath --- include/linux/tracehook.h | 21 +++++++++++++-------- kernel/exit.c | 6 +++--- 2 files changed, 16 insertions(+), 11 deletions(-) diff --git a/include/linux/tracehook.h b/include/linux/tracehook.h index b187558..1253283 100644 --- a/include/linux/tracehook.h +++ b/include/linux/tracehook.h @@ -493,16 +493,21 @@ static inline int tracehook_notify_jctl(int notify, int why) * @death_cookie: value to pass to tracehook_report_death() * @group_dead: nonzero if this was the last thread in the group to die * - * Return the signal number to send our parent with do_notify_parent(), or - * zero to send no signal and leave a zombie, or -1 to self-reap right now. + * A return value >= 0 means call do_notify_parent() with that signal + * number. Negative return value can be %DEATH_REAP to self-reap right + * now, or %DEATH_DELAYED_GROUP_LEADER to a zombie without notifying our + * parent. Note that a return value of 0 means a do_notify_parent() call + * that sends no signal, but still wakes up a parent blocked in wait*(). * * Called with write_lock_irq(&tasklist_lock) held. */ +#define DEATH_REAP -1 +#define DEATH_DELAYED_GROUP_LEADER -2 static inline int tracehook_notify_death(struct task_struct *task, void **death_cookie, int group_dead) { if (task->exit_signal == -1) - return task->ptrace ? SIGCHLD : -1; + return task->ptrace ? SIGCHLD : DEATH_REAP; /* * If something other than our normal parent is ptracing us, then @@ -512,21 +517,21 @@ static inline int tracehook_notify_death(struct task_struct *task, if (thread_group_empty(task) && !ptrace_reparented(task)) return task->exit_signal; - return task->ptrace ? SIGCHLD : 0; + return task->ptrace ? SIGCHLD : DEATH_DELAYED_GROUP_LEADER; } /** * tracehook_report_death - task is dead and ready to be reaped * @task: @current task now exiting - * @signal: signal number sent to parent, or 0 or -1 + * @signal: return value from tracheook_notify_death() * @death_cookie: value passed back from tracehook_notify_death() * @group_dead: nonzero if this was the last thread in the group to die * * Thread has just become a zombie or is about to self-reap. If positive, * @signal is the signal number just sent to the parent (usually %SIGCHLD). - * If @signal is -1, this thread will self-reap. If @signal is 0, this is - * a delayed_group_leader() zombie. The @death_cookie was passed back by - * tracehook_notify_death(). + * If @signal is %DEATH_REAP, this thread will self-reap. If @signal is + * %DEATH_DELAYED_GROUP_LEADER, this is a delayed_group_leader() zombie. + * The @death_cookie was passed back by tracehook_notify_death(). * * If normal reaping is not inhibited, @task->exit_state might be changing * in parallel. diff --git a/kernel/exit.c b/kernel/exit.c index eb4d647..38ec406 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -911,10 +911,10 @@ static void exit_notify(struct task_struct *tsk, int group_dead) tsk->exit_signal = SIGCHLD; signal = tracehook_notify_death(tsk, &cookie, group_dead); - if (signal > 0) + if (signal >= 0) signal = do_notify_parent(tsk, signal); - tsk->exit_state = signal < 0 ? EXIT_DEAD : EXIT_ZOMBIE; + tsk->exit_state = signal == DEATH_REAP ? EXIT_DEAD : EXIT_ZOMBIE; /* mt-exec, de_thread() is waiting for us */ if (thread_group_leader(tsk) && @@ -927,7 +927,7 @@ static void exit_notify(struct task_struct *tsk, int group_dead) tracehook_report_death(tsk, signal, cookie, group_dead); /* If the process is dead, release it - nobody will wait for it */ - if (signal < 0) + if (signal == DEATH_REAP) release_task(tsk); } -- 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/