From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759388Ab3BXRdl (ORCPT ); Sun, 24 Feb 2013 12:33:41 -0500 Received: from mx1.redhat.com ([209.132.183.28]:43494 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759370Ab3BXRdj (ORCPT ); Sun, 24 Feb 2013 12:33:39 -0500 Date: Sun, 24 Feb 2013 18:32:09 +0100 From: Oleg Nesterov To: Andrew Morton Cc: Mandeep Singh Baines , Neil Horman , "Rafael J. Wysocki" , Tejun Heo , linux-kernel@vger.kernel.org Subject: [PATCH 3/3] coredump: make wait_for_dump_helpers() freezable Message-ID: <20130224173209.GA32209@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130224173144.GA32179@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org wait_for_dump_helpers() calls wake_up/kill_fasync from inside the wait_event-like loop. This is not needed and in fact this is not strictly correct, we can/should do this only once after we change pipe->writers. We could even check if it becomes zero. With this change it is trivial to convert this code to use wait_event_freezable() and make this function freezable/killable, only SIGKILL can set TIF_SIGPENDING. With this patch we check pipe->readers without pipe_lock(), this is fine. Once we see pipe->readers == 1 we know that the handler decremented the counter, this is all we need. Note: wait_event_freezable() is "strange", perhaps it should be changed or simply removed. In the latter case we can change this code again to use freezer_do_not_count + wait_event_interruptible. Signed-off-by: Oleg Nesterov --- fs/coredump.c | 12 ++++++------ 1 files changed, 6 insertions(+), 6 deletions(-) diff --git a/fs/coredump.c b/fs/coredump.c index 4f3c8d1..284d841 100644 --- a/fs/coredump.c +++ b/fs/coredump.c @@ -32,6 +32,7 @@ #include #include #include +#include #include #include @@ -428,17 +429,16 @@ static void wait_for_dump_helpers(struct file *file) pipe_lock(pipe); pipe->readers++; pipe->writers--; + wake_up_interruptible_sync(&pipe->wait); + kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); + pipe_unlock(pipe); - while ((pipe->readers > 1) && (!signal_pending(current))) { - wake_up_interruptible_sync(&pipe->wait); - kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); - pipe_wait(pipe); - } + wait_event_freezable(pipe->wait, pipe->readers == 1); + pipe_lock(pipe); pipe->readers--; pipe->writers++; pipe_unlock(pipe); - } /* -- 1.5.5.1