From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759148AbYG0URa (ORCPT ); Sun, 27 Jul 2008 16:17:30 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757773AbYG0URW (ORCPT ); Sun, 27 Jul 2008 16:17:22 -0400 Received: from www.tglx.de ([62.245.132.106]:48239 "EHLO www.tglx.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757740AbYG0URV (ORCPT ); Sun, 27 Jul 2008 16:17:21 -0400 Date: Sun, 27 Jul 2008 22:15:57 +0200 (CEST) From: Thomas Gleixner To: Linus Torvalds cc: Andrew Morton , LKML , Ingo Molnar , Oleg Nesterov Subject: [GIT pull] timer fixes for .27 Message-ID: User-Agent: Alpine 1.10 (LFD 962 2008-03-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Linus, please pull timer fixes from ssh://master.kernel.org/pub/scm/linux/kernel/git/x86/linux-2.6-tip.git timers/urgent Thanks, tglx ---- Oleg Nesterov (2): posix-timers: fix posix_timer_event() vs dequeue_signal() race posix-timers: do_schedule_next_timer: fix the setting of ->si_overrun posix-timers.c | 19 ++++++++++++++----- signal.c | 1 + 2 files changed, 15 insertions(+), 5 deletions(-) diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c index dbd8398..0ffaeb0 100644 --- a/kernel/posix-timers.c +++ b/kernel/posix-timers.c @@ -289,21 +289,29 @@ void do_schedule_next_timer(struct siginfo *info) else schedule_next_timer(timr); - info->si_overrun = timr->it_overrun_last; + info->si_overrun += timr->it_overrun_last; } if (timr) unlock_timer(timr, flags); } -int posix_timer_event(struct k_itimer *timr,int si_private) +int posix_timer_event(struct k_itimer *timr, int si_private) { - memset(&timr->sigq->info, 0, sizeof(siginfo_t)); + /* + * FIXME: if ->sigq is queued we can race with + * dequeue_signal()->do_schedule_next_timer(). + * + * If dequeue_signal() sees the "right" value of + * si_sys_private it calls do_schedule_next_timer(). + * We re-queue ->sigq and drop ->it_lock(). + * do_schedule_next_timer() locks the timer + * and re-schedules it while ->sigq is pending. + * Not really bad, but not that we want. + */ timr->sigq->info.si_sys_private = si_private; - /* Send signal to the process that owns this timer.*/ timr->sigq->info.si_signo = timr->it_sigev_signo; - timr->sigq->info.si_errno = 0; timr->sigq->info.si_code = SI_TIMER; timr->sigq->info.si_tid = timr->it_id; timr->sigq->info.si_value = timr->it_sigev_value; @@ -435,6 +443,7 @@ static struct k_itimer * alloc_posix_timer(void) kmem_cache_free(posix_timers_cache, tmr); tmr = NULL; } + memset(&tmr->sigq->info, 0, sizeof(siginfo_t)); return tmr; } diff --git a/kernel/signal.c b/kernel/signal.c index 72bb4f5..13fab98 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -1280,6 +1280,7 @@ int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group) q->info.si_overrun++; goto out; } + q->info.si_overrun = 0; signalfd_notify(t, sig); pending = group ? &t->signal->shared_pending : &t->pending;