From mboxrd@z Thu Jan 1 00:00:00 1970 From: Elias Oltmanns Subject: Re: [PATCH 3/4] ide: Implement disk shock protection support Date: Fri, 12 Sep 2008 13:55:17 +0200 Message-ID: <87ljxxy3x6.fsf@denkblock.local> References: <87wshzplvk.fsf@denkblock.local> <200809012129.14979.bzolnier@gmail.com> <87ljy90zin.fsf@denkblock.local> <200809051933.38888.bzolnier@gmail.com> <87vdx1y9gv.fsf@denkblock.local> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from nebensachen.de ([195.34.83.29]:52357 "EHLO mail.nebensachen.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752083AbYILL4l (ORCPT ); Fri, 12 Sep 2008 07:56:41 -0400 In-Reply-To: <87vdx1y9gv.fsf@denkblock.local> (Elias Oltmanns's message of "Fri, 12 Sep 2008 11:55:28 +0200") Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Bartlomiej Zolnierkiewicz Cc: Alan Cox , Andrew Morton , Jeff Garzik , Randy Dunlap , Tejun Heo , linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org Elias Oltmanns wrote: > Bartlomiej Zolnierkiewicz wrote: [...] >> Since Tejun already raised concerns about multiplexing per-device >> and per-port settings I'm not repeating them here. Please just >> remember to backport fixes from libata version to ide one. > > For the sake of consistency, I've always tried to make ide and libata > behave alike (or as close to it as possible). However, the final version > of the libata patch is very hard to mimc in ide. Therefore, I wonder > whether we can do in ide what we'd really like to do in libata > eventually. The patch below is a real per-device implementation of the > unload feature. However, I'd like you to confirm the crucial assumption > underlying this patch: a port reset is the only way a device can > interfere with another device on the same port. In particular, I haven't > made an effort to understand pnp and similar stuff completely, but from > a first glance I got the impression that these things are done per-port > rather than per-device and that nothing sinister will happen behind our > back. In short, can you confirm the following: > > Condition: device A on a port is parked (implies there is at least one > request on the queue of that device, i.e we hold a > reference to the device and thus to the port). > Assumption: nothing will disturb the device because resets due to > command failure / timeouts on device B are deferred (see my > patch) and spurious commands like IDENTIFY (or whatever > actions may be related to pnp and the like) are not > performed while the device is sleeping and a request is > waiting on the queue. Sorry for spamming you again, but I forgot to mention one more thing: In my hardware environment, I cannot easily test the code in do_reset1() which is supposed to defer resets if necessary. Since we have something very similar in libata (which I have tested), I'm quite confident that everything will work out nicely. Still, you may want to pay special attention to this piece of code. Regards, Elias