Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756176AbYJJJhm (ORCPT ); Fri, 10 Oct 2008 05:37:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752442AbYJJJhc (ORCPT ); Fri, 10 Oct 2008 05:37:32 -0400 Received: from nebensachen.de ([195.34.83.29]:41151 "EHLO mail.nebensachen.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751991AbYJJJhb (ORCPT ); Fri, 10 Oct 2008 05:37:31 -0400 X-Hashcash: 1:20:081010:jens.axboe@oracle.com::CTIqV40G7HDO2Hie:00000000000000000000000000000000000000005rt9 X-Hashcash: 1:20:081010:bzolnier@gmail.com::EPD+jDlT0LUSea3l:000000000000000000000000000000000000000000027DW X-Hashcash: 1:20:081010:linux-ide@vger.kernel.org::pMZK3GP0e+QJvKFF:000000000000000000000000000000000000BJBh X-Hashcash: 1:20:081010:linux-kernel@vger.kernel.org::S542GWDpAJrsYwGB:00000000000000000000000000000000010YF From: Elias Oltmanns To: Jens Axboe Cc: Bartlomiej Zolnierkiewicz , linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 4/7] ide: ide_hwgroup_t.rq doesn't need an ide_lock held References: <20081008202930.19112.90371.sendpatchset@localhost.localdomain> <20081008203002.19112.519.sendpatchset@localhost.localdomain> <87abdcg86j.fsf@denkblock.local> <20081010090116.GX19428@kernel.dk> Date: Fri, 10 Oct 2008 11:37:22 +0200 In-Reply-To: <20081010090116.GX19428@kernel.dk> (Jens Axboe's message of "Fri, 10 Oct 2008 11:01:17 +0200") Message-ID: <87wsggdc4t.fsf@denkblock.local> User-Agent: Gnus/5.110007 (No Gnus v0.7) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1674 Lines: 48 Jens Axboe wrote: > On Fri, Oct 10 2008, Elias Oltmanns wrote: >> Bartlomiej Zolnierkiewicz wrote: > >> > From: Bartlomiej Zolnierkiewicz >> > Subject: [PATCH] ide: ide_hwgroup_t.rq doesn't need an ide_lock held >> > >> > While at it: >> > - no need to check for hwgroup presence in ide_dump_opcode() >> > >> > Signed-off-by: Bartlomiej Zolnierkiewicz >> > --- >> [...] >> > Index: b/drivers/ide/ide-io.c >> > =================================================================== >> > --- a/drivers/ide/ide-io.c >> > +++ b/drivers/ide/ide-io.c >> [...] >> > @@ -274,7 +269,11 @@ static void ide_complete_pm_request (ide >> > drive->dev_flags &= ~IDE_DFLAG_BLOCKED; >> > blk_start_queue(drive->queue); >> > } >> > - HWGROUP(drive)->rq = NULL; >> > + spin_unlock_irqrestore(&ide_lock, flags); >> > + >> > + drive->hwif->hwgroup->rq = NULL; >> > + >> > + spin_lock_irqsave(&ide_lock, flags); >> > if (__blk_end_request(rq, 0, 0)) >> > BUG(); >> > spin_unlock_irqrestore(&ide_lock, flags); >> >> Is it really an improvement to release the lock here? > > And more importantly, is it even safe? What serializes ->rq assignments > and checks without the ide_lock? Looks fishy. Well, I haven't quite made up my mind whether it'll work in all cases, but I think the hwgroup->busy flag is supposed to take care of that. Regards, Elias -- 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/