Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764021AbXK3C6p (ORCPT ); Thu, 29 Nov 2007 21:58:45 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1764043AbXK3C6W (ORCPT ); Thu, 29 Nov 2007 21:58:22 -0500 Received: from netrider.rowland.org ([192.131.102.5]:2972 "HELO netrider.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1764019AbXK3C6V (ORCPT ); Thu, 29 Nov 2007 21:58:21 -0500 Date: Thu, 29 Nov 2007 21:58:20 -0500 (EST) From: Alan Stern X-X-Sender: stern@netrider.rowland.org To: Linus Torvalds cc: Mark Lord , Greg KH , Andrew Morton , , Linux Kernel Subject: Re: [linux-usb-devel] [PATCH] base/class.c: prevent ooops due to insert/remove race (v3) In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1834 Lines: 49 On Thu, 29 Nov 2007, Linus Torvalds wrote: > Heh. It definitely hasn't gotten lost by "the git software". No, it sure hasn't. In fact it was staring me right in the face and I didn't realize it. > In fact, with > the kinds of hints you already gave, git makes it really _trivial_ to find > it. > > Here's what you do: > > git log v2.6.23.. --author=Wilcox > > and then just search for "scan_mutex", in the hope that Matthew wrote a > nice commit message. And yes, he did, so in less than a blink you get: > > commit 6b7f123f378743d739377871c0cbfbaf28c7d25a > Author: Matthew Wilcox > Date: Tue Jun 26 15:18:51 2007 -0600 > > [SCSI] Fix async scanning double-add problems > > Stress-testing and some thought has revealed some places where > asynchronous scanning needs some more attention to locking. > > - Since async_scan is a bit, we need to hold the host_lock while > modifying it to prevent races against other CPUs modifying the word > that bit is in. This is probably a theoretical race for the moment, > but other patches may change that. > - The async_scan bit means not only that this host is being scanned > asynchronously, but that all the devices attached to this host are not > yet added to sysfs. So we must ensure that this bit is always in sync. > I've chosen to do this with the scan_mutex since it's already acquired > in most of the right places. > ... > > which I assume is the commit you're talking about. Yep, that's the one. Alan Stern - 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/