Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753299Ab0BWRCJ (ORCPT ); Tue, 23 Feb 2010 12:02:09 -0500 Received: from smtp1.linux-foundation.org ([140.211.169.13]:41336 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753297Ab0BWRCF (ORCPT ); Tue, 23 Feb 2010 12:02:05 -0500 Date: Tue, 23 Feb 2010 09:00:58 -0800 (PST) From: Linus Torvalds X-X-Sender: torvalds@localhost.localdomain To: Greg KH cc: Stefan Bader , Greg KH , Kiyoshi Ueda , linux-kernel@vger.kernel.org, stable-review@kernel.org, alan@lxorguk.ukuu.org.uk, Junichi Nomura , akpm@linux-foundation.org, stable@kernel.org, Alasdair G Kergon Subject: Re: [Stable-review] [93/93] dm mpath: fix stall when requeueing io In-Reply-To: <20100223153326.GA4275@kroah.com> Message-ID: References: <20100219163257.186977438@kvm.kroah.org> <4B815A3D.9040402@canonical.com> <20100223153326.GA4275@kroah.com> User-Agent: Alpine 2.00 (LFD 1167 2008-08-23) 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: 1404 Lines: 38 On Tue, 23 Feb 2010, Greg KH wrote: > On Sun, Feb 21, 2010 at 05:07:25PM +0100, Stefan Bader wrote: > > > > > > Signed-off-by: Kiyoshi Ueda > > > Signed-off-by: Jun'ichi Nomura > > > Signed-off-by: Alasdair G Kergon > > > > > > blk_start_request(rq); > > > spin_unlock(q->queue_lock); > > > - map_request(ti, rq, md); > > > + if (map_request(ti, rq, md)) > > > + goto requeued; > > > spin_lock_irq(q->queue_lock); > > > } > > > > While looking over the code I also noticed that the spinlock is dropped with > > spin_unlock and then reacquired with spin_lock_irq. Isn't the irq version too > > much in that case? Or was the intention to have interrupts enabled when unlocking? > > Ick, thanks for the review. I'll drop this patch for now and fix it up > in the next release if needed. This part of the commentary seems to be relevant for mainline too. According to git logs, this spin_unlock/spin_lock_irq imbalance goes back to commit cec47e3d4a (last June). Maybe there's some reason for it, but it does look odd. Ueda-san, Nomura-san, Alasdair? Comments? Linus -- 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/