Date: Sun, 4 Apr 2004 13:21:38 -0700 (PDT) From: Doug Ambrisko <ambrisko@ambrisko.com> To: Poul-Henning Kamp <phk@phk.freebsd.dk> Cc: =?ISO-8859-1?Q?S=F8ren_Schmidt?= <sos@DeepCore.dk> Subject: Re: Intel SATA ICH5/5R 6300ESB support patches Message-ID: <200404042021.i34KLcVT039830@ambrisko.com> In-Reply-To: <1839.1081109842@critter.freebsd.dk>
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Poul-Henning Kamp writes: | In message <200404042002.i34K2nop038808@ambrisko.com>, Doug Ambrisko writes: | >Søren Schmidt writes: | | >| > I put in a patch for geom for bio_taskqueue_remove. Since ata code | >| > schedules bio_task it need to be cancelled when we abort and call | >| > biodone. If we don't cancel this task then when the task is | >| > run later we get a double free in UMA since we have cleaned up | >| > twice and called biodone twice for the same request. | | Sos@ forwarded that patch and it won't fly, it has no chance of | working reliably on multi-cpu machines: | | There is no guarantee that the task is still on the queue by the | time you try to remove it, and if is not, it is likely to be because | another CPU is already waiting for a lock in the ata driver in the | bio_taskqueue handler function, so we have no way to cancel that | other CPU's activity. | | The correct solution is to not do the biodone when you cancel, but | let the already scheduled bio_taskqueue event to do so. Okay, I'll look at the ata code so that it only does it once. Thanks, Doug A.
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