From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Dave Young" Subject: Re: [PATCH][-mm] reclassify sg_sysfs_class for lockdep Date: Thu, 29 May 2008 08:45:43 +0800 Message-ID: References: <20080527101009.GA3015@darkstar.te-china.tietoenator.com> <1211985600.3445.14.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1211985600.3445.14.camel@localhost.localdomain> Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org To: James Bottomley Cc: akpm@linux-foundation.org, greg@kroah.com, matthew@wil.cx, kay.sievers@vrfy.org, linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org List-Id: linux-scsi@vger.kernel.org On Wed, May 28, 2008 at 10:40 PM, James Bottomley wrote: > On Tue, 2008-05-27 at 18:10 +0800, Dave Young wrote: >> As register sg_interface, the sg_add will be called, which then will >> add device to sg_sysfs_class. This will cause lockdep warning, >> please see following email >> >> In this case the locks are from diffrent classi, one is sdev_class, >> another is sg_sysfs_class >> >> Here reclassify the sg_sysfs_class for lockdep > > This isn't really a generic solution, is it? It only works because we > currently only have two users of the interface functions, so if we > reclassify one they look separate to lockdep. It will fall over again > if we ever get another one. > > Surely the correct fix is to initialise lockdep for the mutex the same > way we did for the semaphore in class_register() (which does exactly the > same locking without triggering lockdep)? That way we'll also fix the > problem for other conversions of semaphore->mutex. Matthew & greg did the work already. >>From my original idea I don't want to do this for all classes, and I would think it as a rare case. Regards dave