From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [PATCH 2/4 v2] libata: Implement disk shock protection support Date: Fri, 19 Sep 2008 07:15:10 -0700 Message-ID: <48D3B3EE.70702@gmail.com> References: <87d4j2n3dn.fsf@denkblock.local> <20080917163144.9870.97008.stgit@denkblock.local> <48D147E2.3020601@gmail.com> <87skrwmpng.fsf@denkblock.local> <48D3979F.10305@gmail.com> <87ljxokz67.fsf@denkblock.local> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from wa-out-1112.google.com ([209.85.146.183]:57829 "EHLO wa-out-1112.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750927AbYISOQu (ORCPT ); Fri, 19 Sep 2008 10:16:50 -0400 Received: by wa-out-1112.google.com with SMTP id j37so345599waf.23 for ; Fri, 19 Sep 2008 07:16:49 -0700 (PDT) In-Reply-To: <87ljxokz67.fsf@denkblock.local> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Elias Oltmanns Cc: Bartlomiej Zolnierkiewicz , Jeff Garzik , Randy Dunlap , linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org Elias Oltmanns wrote: >> This should basically work but completion isn't really designed for >> this type of continuous events where single consumption should clear >> all pending events. INIT_COMPLETION comes close but it doesn't lock, >> so can't guarantee anything. What's necessary is the counterpart for >> complete_all() for the wait. > > You are right that it isn't designed for this use case and my approach > is somewhat hackish. Still, it really does exactly what we want. Please > note that ap->park_req_pending is protected by the host lock; the call > to complete() is atomic wrt the setting of ATA_EH_PARK for one of the > devices on the port and so is the call to INIT_COMPLETION() wrt clearing > ATA_EH_PARK requests for *all* devices on the port. > >> Well, anyways, I think the issue is slightly out of scope for this >> patch and the only side effect is possibly looping over the do {} >> while () block several times unnecessarily on certain cases, so I >> think just noting about it should be enough for now. >> >> Can you please add explanation above wait_for_complete_timeout() that >> all done counts should be cleared here but aren't and as a result the >> loop might repeat determinate number of times unnecessarily and resend >> as proper patch? > > Well, we don't really care about the done count after > wait_for_completion_timeout() has returned. All that matters is that the > done counter is cleared when all ATA_EH_PARK actions have been pulled in > which happens at the start of each cycle over the loop. > > Perhaps I should add comments to this effect before > wait_for_completion_timeout() as well as INIT_COMPLETION()? Ah... I missed the pull_park_action part. Yes, in that case, it's correct now but I would really appreciate you explain amply what's going on inside the pull function and why it's needed. Thanks. -- tejun