From owner-freebsd-usb@FreeBSD.ORG Wed May 25 15:22:29 2011 Return-Path: Delivered-To: freebsd-usb@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 8C06C106564A for ; Wed, 25 May 2011 15:22:29 +0000 (UTC) (envelope-from hselasky@freebsd.org) Received: from swip.net (mailfe03.c2i.net [212.247.154.66]) by mx1.freebsd.org (Postfix) with ESMTP id 18DDF8FC08 for ; Wed, 25 May 2011 15:22:28 +0000 (UTC) X-Cloudmark-Score: 0.000000 [] X-Cloudmark-Analysis: v=1.1 cv=0KkIQGagYCvnrzE3Z2Lmid87OPdbX6VLcZYwAuLMZ50= c=1 sm=1 a=SvYTsOw2Z4kA:10 a=4j0xZboyc7kA:10 a=dBRESv0yCI8A:10 a=N659UExz7-8A:10 a=CL8lFSKtTFcA:10 a=i9M/sDlu2rpZ9XS819oYzg==:17 a=9V2TONt1Lu6oPUjB0NEA:9 a=pILNOxqGKmIA:10 a=i9M/sDlu2rpZ9XS819oYzg==:117 Received: from [188.126.198.129] (account mc467741@c2i.net HELO laptop002.hselasky.homeunix.org) by mailfe03.swip.net (CommuniGate Pro SMTP 5.2.19) with ESMTPA id 131752424; Wed, 25 May 2011 17:12:24 +0200 Received-SPF: softfail receiver=mailfe03.swip.net; client-ip=188.126.198.129; envelope-from=hselasky@freebsd.org From: Hans Petter Selasky To: Andriy Gapon Date: Wed, 25 May 2011 17:11:09 +0200 User-Agent: KMail/1.13.5 (FreeBSD/8.2-STABLE; KDE/4.4.5; amd64; ; ) References: <86FB7D63AF95574BB762C0C3E1F269150D8B14AB@RTPMVEXC1-PRD.hq.netapp.com> <4DDD19C4.6090705@FreeBSD.org> In-Reply-To: <4DDD19C4.6090705@FreeBSD.org> X-Face: *nPdTl_}RuAI6^PVpA02T?$%Xa^>@hE0uyUIoiha$pC:9TVgl.Oq, NwSZ4V"|LR.+tj}g5 %V,x^qOs~mnU3]Gn; cQLv&.N>TrxmSFf+p6(30a/{)KUU!s}w\IhQBj}[g}bj0I3^glmC( :AuzV9:.hESm-x4h240C`9=w MIME-Version: 1.0 Content-Type: Text/Plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Message-Id: <201105251711.09594.hselasky@freebsd.org> Cc: "Shah, Vishal" , "Ranaweera, Samantha" , "Faylor, Christopher" , "freebsd-usb@FreeBSD.org" Subject: Re: System hang in USB umass module while processing panic X-BeenThere: freebsd-usb@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: FreeBSD support for USB List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 25 May 2011 15:22:29 -0000 On Wednesday 25 May 2011 17:01:24 Andriy Gapon wrote: > on 19/05/2011 22:27 Shah, Vishal said the following: > > In FreeBSD 8 USB driver, commands are asynchronously sent from umass > > layer onto the wire, in other words, multiple threads are involved > > before the command is sent from the umass layer all the way to the wire. > > Since the usb_proc is not scheduled current process keeps waiting for > > the command to complete, hence the hang. Is this a known issue? If yes, > > is there a fix available? Are there any plans of adding a synchronous > > path to send the command to the device? Any information regarding this > > issue is much appreciated. > > From your description this sounds like a problem in USB driver. > I am not an expert in USB code, looks like some polling prodding would have > to be added there (if it's not there yet). Hans Petter may be a better > contact for this issue. > I am not sure if I can help you more. Hi, The umass driver is being polled during panic. If some command is hanging on a USB device then USB cannot do anything about it. Only the CAM layer can abort the SCSI command, because the USB layer doesn't know if it is the dump device or not? Sometimes the command timeouts are rather longs so waiting until the command times out might work to get a core dump. --HPS