From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754479Ab1IBS2X (ORCPT ); Fri, 2 Sep 2011 14:28:23 -0400 Received: from mail-pz0-f42.google.com ([209.85.210.42]:48944 "EHLO mail-pz0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754356Ab1IBS2M (ORCPT ); Fri, 2 Sep 2011 14:28:12 -0400 From: Tejun Heo To: oleg@redhat.com, matthltc@us.ibm.com, rjw@sisk.pl, paul@paulmenage.org Cc: containers@lists.linux-foundation.org, linux-pm@lists.linux-foundation.org, linux-kernel@vger.kernel.org, Tejun Heo Subject: [PATCH 3/6] freezer: restructure __refrigerator() Date: Sat, 3 Sep 2011 03:27:47 +0900 Message-Id: <1314988070-12244-4-git-send-email-tj@kernel.org> X-Mailer: git-send-email 1.7.6 In-Reply-To: <1314988070-12244-1-git-send-email-tj@kernel.org> References: <1314988070-12244-1-git-send-email-tj@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If another freeze happens before all tasks leave FROZEN state after being thawed, the freezer can see the existing FROZEN and consider the tasks to be frozen but they can clear FROZEN without checking the new freezing(). Oleg suggested restructuring __refrigerator() such that there's single condition check section inside freezer_lock and sigpending is cleared afterwards, which fixes the problem and simplifies the code. Restructure accordingly. -v2: Frozen loop exited without releasing freezer_lock. Fixed. Signed-off-by: Tejun Heo Reported-by: Oleg Nesterov Cc: "Rafael J. Wysocki" --- kernel/freezer.c | 29 +++++++++++------------------ 1 files changed, 11 insertions(+), 18 deletions(-) diff --git a/kernel/freezer.c b/kernel/freezer.c index 466ea6b..ebee1ab 100644 --- a/kernel/freezer.c +++ b/kernel/freezer.c @@ -52,36 +52,29 @@ bool __refrigerator(bool check_kthr_stop) /* Hmm, should we be allowed to suspend when there are realtime processes around? */ bool was_frozen = false; - long save; + long save = current->state; - /* - * No point in checking freezing() again - the caller already did. - * Proceed to enter FROZEN. - */ - spin_lock_irq(&freezer_lock); - current->flags |= PF_FROZEN; - spin_unlock_irq(&freezer_lock); - - save = current->state; pr_debug("%s entered refrigerator\n", current->comm); - spin_lock_irq(¤t->sighand->siglock); - recalc_sigpending(); /* We sent fake signal, clean it up */ - spin_unlock_irq(¤t->sighand->siglock); - for (;;) { set_current_state(TASK_UNINTERRUPTIBLE); + + spin_lock_irq(&freezer_lock); + current->flags |= PF_FROZEN; if (!freezing(current) || (check_kthr_stop && kthread_should_stop())) + current->flags &= ~PF_FROZEN; + spin_unlock_irq(&freezer_lock); + + if (!(current->flags & PF_FROZEN)) break; was_frozen = true; schedule(); } - /* leave FROZEN */ - spin_lock_irq(&freezer_lock); - current->flags &= ~PF_FROZEN; - spin_unlock_irq(&freezer_lock); + spin_lock_irq(¤t->sighand->siglock); + recalc_sigpending(); /* We sent fake signal, clean it up */ + spin_unlock_irq(¤t->sighand->siglock); pr_debug("%s left refrigerator\n", current->comm); -- 1.7.6