Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261912AbVANEzk (ORCPT ); Thu, 13 Jan 2005 23:55:40 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261906AbVANEzj (ORCPT ); Thu, 13 Jan 2005 23:55:39 -0500 Received: from smtp.nuvox.net ([64.89.70.9]:16212 "EHLO smtp04.gnvlscdb.sys.nuvox.net") by vger.kernel.org with ESMTP id S261894AbVANEzU (ORCPT ); Thu, 13 Jan 2005 23:55:20 -0500 Subject: Re: [UPDATE PATCH] ieee1394/sbp2: use ssleep() instead of schedule_timeout() From: Dan Dennedy To: Nishanth Aravamudan Cc: Stefan Richter , Linux1394-Devel , kj , lkml , Ben Collins In-Reply-To: <20050110173945.GB3099@us.ibm.com> References: <20050107213400.GD2924@us.ibm.com> <17a9eec54394ded0a28295a6548a5c65@localhost> <20050110173945.GB3099@us.ibm.com> Content-Type: text/plain Date: Thu, 13 Jan 2005 23:52:55 -0500 Message-Id: <1105678375.7830.81.camel@kino.dennedy.org> Mime-Version: 1.0 X-Mailer: Evolution 2.0.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2846 Lines: 62 On Mon, 2005-01-10 at 09:39 -0800, Nishanth Aravamudan wrote: > On Sun, Jan 09, 2005 at 10:01:21AM +0100, Stefan Richter wrote: > > Nishanth Aravamudan wrote: > > >Description: Use ssleep() instead of schedule_timeout() to guarantee > > >the task > > >delays as expected. The existing code should not really need to run in > > >TASK_INTERRUPTIBLE, as there is no check for signals (or even an > > >early return > > >value whatsoever). ssleep() takes care of these issues. > > > > >--- 2.6.10-v/drivers/ieee1394/sbp2.c 2004-12-24 13:34:00.000000000 > > >-0800 > > >+++ 2.6.10/drivers/ieee1394/sbp2.c 2005-01-05 14:23:05.000000000 -0800 > > >@@ -902,8 +902,7 @@ alloc_fail: > > > * connected to the sbp2 device being removed. That host would > > > * have a certain amount of time to relogin before the sbp2 device > > > * allows someone else to login instead. One second makes sense. */ > > >- set_current_state(TASK_INTERRUPTIBLE); > > >- schedule_timeout(HZ); > > >+ ssleep(1); > > > > Maybe the current code is _deliberately_ accepting interruption by > > signals but trying to complete sbp2_probe() anyway. However it seems > > more plausible to me to abort the device probe, for example like this: > > if (msleep_interruptible(1000)) { > > sbp2_remove_device(scsi_id); > > return -EINTR; > > } > > You might be right, but I'd like to get Ben's input on this, as I honeslty am Don't hold your breath waiting for Ben's input. However, I would like to get one of the two proposed committed and tested by more users as this is a sore spot. I am not in a position at this time to fully research and test to make a call. > unsure. To be fair, I am trying to audit all usage of schedule_timeout() and the > semantic interpretation (to me) of using TASK_INTERRUPTIBLE is that you wish to > sleep a certain amount of time, but also are prepared for an early return on > either signals or wait-queue events. msleep_interruptible() cleanly removes this > second issue, but still requires the caller to respond appropriately if there is > a return value. Hence, I like your change. I think it makes the most sense. > Since I didn't/don't know how the device works, I was not able to make the > change myself. Thanks for your input! Sounds like a sign-off. Any other input before I request Stefan to make the final decision? > > Anyway, signal handling does not appear to be critical there. > > Just out of curiousity, doesn't that run the risk, though, of > signal_pending(current) being true for quite a bit of time following the > timeout? How much of this is "curiosity" vs a real risk? - 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/