From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Hutchings Subject: Re: [PATCH 1/3] pci: VPD access timeout increase Date: Thu, 4 Sep 2008 15:19:46 +0100 Message-ID: <20080904141944.GE7908@solarflare.com> References: <20080827204626.4b65862f@extreme> <20080828111323.GI7908@solarflare.com> <20080903155713.7fab2e19@extreme> <20080904125219.GJ2772@parisc-linux.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Stephen Hemminger , Jesse Barnes , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-pci@vger.kernel.org To: Matthew Wilcox Return-path: Received: from smarthost01.mail.zen.net.uk ([212.23.3.140]:54624 "EHLO smarthost01.mail.zen.net.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750958AbYIDOTx (ORCPT ); Thu, 4 Sep 2008 10:19:53 -0400 Content-Disposition: inline In-Reply-To: <20080904125219.GJ2772@parisc-linux.org> Sender: netdev-owner@vger.kernel.org List-ID: Matthew Wilcox wrote: > On Wed, Sep 03, 2008 at 03:57:13PM -0700, Stephen Hemminger wrote: > > Accessing the VPD area can take a long time. There are comments in the > > SysKonnect vendor driver that it can take up to 25ms. The existing vpd > > access code fails consistently on my hardware. > > Wow, that's slow. If you were to try to read all 32k, it'd take more > than three minutes! (I presume it doesn't actually have as much as 32k). > > > Change the access routines to: > > * use a mutex rather than spinning with IRQ's disabled and lock held > > * have a longer timeout > > * call schedule while spinning to provide some responsivness > > I agree with your approach, but have one minor comment: > > > - spin_lock_irq(&vpd->lock); > > + mutex_lock(&vpd->lock); > > This should be: > > + if (mutex_lock_interruptible(&vpd->lock)) > + return -EINTR; [...] This is fine for the sysfs case, but not if this is called during device probe - we don't want signals to modprobe to break device initialisation, do we? Ben. -- Ben Hutchings, Senior Software Engineer, Solarflare Communications Not speaking for my employer; that's the marketing department's job. They asked us to note that Solarflare product names are trademarked.