Date: Sun, 4 Apr 2004 13:22:30 -0700 (PDT) From: Doug Ambrisko <ambrisko@ambrisko.com> To: =?ISO-8859-1?Q?S=F8ren_Schmidt?= <sos@DeepCore.dk> Cc: current@freebsd.org Subject: Re: Intel SATA ICH5/5R 6300ESB support patches Message-ID: <200404042022.i34KMU8C039893@ambrisko.com> In-Reply-To: <40706E1B.4010004@DeepCore.dk>
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Søren Schmidt writes: | Poul-Henning Kamp wrote: | > In message <200404042002.i34K2nop038808@ambrisko.com>, Doug Ambrisko writes: | > | >>S?ren 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. | | Actually I've solved this very differently by now, the problem was the | handling of the "in flight" request, that could cause bidone to be | called twice (which is plain wrong)... Sounds good, Doug A.
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