From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sergei Shtylyov Subject: Re: [BUG] ide dma_timer_expiry, then hard lockup Date: Tue, 19 Jun 2007 20:10:25 +0400 Message-ID: <4677FFF1.2010308@ru.mvista.com> References: <20070618175713.GD5836@austin.ibm.com> <4677E30B.4020101@ru.mvista.com> <20070619150502.GO5836@austin.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from h155.mvista.com ([63.81.120.155]:38321 "EHLO imap.sh.mvista.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1753723AbXFSQIm (ORCPT ); Tue, 19 Jun 2007 12:08:42 -0400 In-Reply-To: <20070619150502.GO5836@austin.ibm.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Linas Vepstas Cc: Stuart_Hayes@Dell.com, linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org Hello. Linas Vepstas wrote: >>Stuart_Hayes@Dell.com wrote: >>>I think reading the IDE status register clears the interrupt in the IDE >>>device, which might be causing the drive to think it's OK to generate >>>another interrupt. >> This is not how IDE drives are supposed to act -- they won't proceed any >>further until "interrupt pending" condition is cleared, so these aren't >>supposed to be "stacked". This behavior however is not strictly specified >>by ATA standards IIRC, but I can't readily imagine such situaltion anyway >>unless tagged command queueing (which is not supported by IDE core) and/or >>ATAPI command overlapping is in action... > The problem only manifests during high io load; perhaps a missing mutex > somewhere is blasting one thing too many out to the hard drive? Hm... not sure about this. >>>This could either cause it to get stuck trying to >>>service an interrupt that is never getting cleared as you suggested, or >>>possibly when the next IRQ comes in the IDE IRQ handler gets stuck >>>waiting for a spinlock that the code you're looking at already owns...? >> I could also imagine the HPT366 chip going mad and stalling the reads if >>the taskfile regs forever because of the incomplete DMA or even the drive >>going mad and not replying to I/O cycles with proper -IORDY handshake (i.e. >>holding it low all the time)... > In my case, ctrl-alt-sysrq doesn't work, which makes it hard to debug. > I'm thinking that trying to debug libata is a better idea, rather than > investing time in ide, right? Although at the moment, libata works even > less; see other email. Which makes me think this really is some *hardware* issue. > --linas MBR, Sergei