Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761518AbXKQKwA (ORCPT ); Sat, 17 Nov 2007 05:52:00 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753381AbXKQKvw (ORCPT ); Sat, 17 Nov 2007 05:51:52 -0500 Received: from ogre.sisk.pl ([217.79.144.158]:59704 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752196AbXKQKvw (ORCPT ); Sat, 17 Nov 2007 05:51:52 -0500 From: "Rafael J. Wysocki" To: Franck Bui-Huu Subject: Re: apm emulation driver broken ? Date: Sat, 17 Nov 2007 12:09:07 +0100 User-Agent: KMail/1.9.6 (enterprise 20070904.708012) Cc: linux-pm@lists.linux-foundation.org, lkml References: <473EAC1A.1000205@gmail.com> <200711171059.57462.rjw@sisk.pl> In-Reply-To: <200711171059.57462.rjw@sisk.pl> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200711171209.09985.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2447 Lines: 76 On Saturday, 17 of November 2007, Rafael J. Wysocki wrote: > On Saturday, 17 of November 2007, Franck Bui-Huu wrote: > > Rafael J. Wysocki wrote: > > > However, using PF_NOFREEZE to prevent this from happening doesn't seem to be > > > a good idea. > > > > > > > Indeed but... > > > > > I'd probably use wait_event_freezable() (defined in > > > include/linux/freezer.h) for that. > > > > ...I would just revert this bits from now to make sure this driver > > work again for v2.6.24. > > I'd prefer not to. > > The PF_NOFREEZE was not present in 2.6.23 already and I wouldn't like to > reintroduce it now. > > Why do you think that using wait_event_freezable() would not work, BTW? > > > > It tries to send them fake signals and waits for them to freeze. If > > > they don't freeze within the timeout, it fails and clears their > > > TIF_FREEZE bits. > > > > But send_fake_signal() seems to wake up task in INTERRUPTIBLE state > > only. Looking at signal_wake_up(), it basically do: > > > > wake_up_state(t, TASK_INTERRUPTIBLE); > > > > What am I missing ? > > Nothing. :-) > > I didn't remember the change that made the freezer use TASK_INTERRUPTIBLE > explicitly in there (should have looked at the current code before replying). Actually, not even that one. You're right anyway. Below is a patch that IMO should fix the issue with apm_ioctl(). Greetings, Rafael --- From: Rafael J. Wysocki The code in apm_ioctl() allows user space tasks waiting for a suspend to complete to be woken up prematurely as a result of the thawing of tasks carried out by the freezer. Fix it. Signed-off-by: Rafael J. Wysocki --- drivers/char/apm-emulation.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) Index: linux-2.6/drivers/char/apm-emulation.c =================================================================== --- linux-2.6.orig/drivers/char/apm-emulation.c +++ linux-2.6/drivers/char/apm-emulation.c @@ -364,7 +364,7 @@ apm_ioctl(struct inode * inode, struct f */ flags = current->flags; - wait_event_interruptible(apm_suspend_waitqueue, + wait_event_freezable(apm_suspend_waitqueue, as->suspend_state == SUSPEND_DONE); } - 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/