Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934524Ab3CHSBT (ORCPT ); Fri, 8 Mar 2013 13:01:19 -0500 Received: from mx1.redhat.com ([209.132.183.28]:16545 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759889Ab3CHSBQ (ORCPT ); Fri, 8 Mar 2013 13:01:16 -0500 Date: Fri, 8 Mar 2013 18:59:20 +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: change wait_for_dump_helpers() to use wait_event_interruptible() Message-ID: <20130308175920.GA26332@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130308175852.GA26300@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 Content-Length: 1768 Lines: 56 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. Change this code to use use wait_event_interruptible(), this can also help to make this wait freezable. 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. Signed-off-by: Oleg Nesterov --- fs/coredump.c | 15 +++++++++------ 1 files changed, 9 insertions(+), 6 deletions(-) diff --git a/fs/coredump.c b/fs/coredump.c index 477f393..667413c 100644 --- a/fs/coredump.c +++ b/fs/coredump.c @@ -439,17 +439,20 @@ 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); - } + /* + * We actually want wait_event_freezable() but then we need + * to clear TIF_SIGPENDING and improve dump_interrupted(). + */ + wait_event_interruptible(pipe->wait, pipe->readers == 1); + pipe_lock(pipe); pipe->readers--; pipe->writers++; pipe_unlock(pipe); - } /* -- 1.5.5.1 -- 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/