From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Bottomley Subject: Re: [PATCH] SCSI: increase default timeout for INQUIRY Date: Thu, 12 Mar 2009 10:15:49 -0500 Message-ID: <1236870949.3248.13.camel@localhost.localdomain> References: <20090312151206.GC14425@parisc-linux.org> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: Received: from accolon.hansenpartnership.com ([76.243.235.52]:60284 "EHLO accolon.hansenpartnership.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755681AbZCLPPz (ORCPT ); Thu, 12 Mar 2009 11:15:55 -0400 In-Reply-To: <20090312151206.GC14425@parisc-linux.org> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Matthew Wilcox Cc: Alan Stern , Paul Wellner Bou , SCSI development list On Thu, 2009-03-12 at 09:12 -0600, Matthew Wilcox wrote: > On Thu, Mar 12, 2009 at 11:08:51AM -0400, Alan Stern wrote: > > It's hard to see how this could cause any signficant problems, unless > > somebody actually depends on INQUIRY timing out. > > Erm, like doing a scan of a bus? With 15 devices to probe, you've > increased the time from 15 * 3 = 45 seconds to 15 * 20 = 300 seconds. > That's not cool ;-( > > Maybe we could default this in the transport or something so USB can > override it. Well, no, this is the overall command timeout. Each bus (that's scannable) has its own timeout. For instance, on a parallel bus this is 250ms per device ... don't respond in that time, we return DID_NO_CONNECT. I think what Alan is saying is that some USB devices will take >5s to respond to an initial inquiry. Remember that USB isn't actually a scannable bus. We get told there's a device there and we have to send an INQUIRY to classify it. James