Messages in this thread | | | Date | Thu, 23 May 2013 13:51:29 +0300 | Subject | Re: [PATCH] dmatest: abort transfers immediately when asked for | From | Andy Shevchenko <> |
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On Thu, May 23, 2013 at 1:09 PM, Vinod Koul <vinod.koul@intel.com> wrote: > On Tue, May 21, 2013 at 08:24:15PM +0300, Andy Shevchenko wrote: >> On Tue, May 21, 2013 at 6:11 PM, Will Deacon <will.deacon@arm.com> wrote: >> > On Tue, May 21, 2013 at 01:33:17PM +0100, Andy Shevchenko wrote: >> >> When thread is going to be stopped we have to unconditionally terminate all >> >> ongoing transfers. Otherwise it would be possible that callback function will >> >> be called on the next interrupt and will try to access to already freed >> >> structures. >> >> >> >> The patch introduces specific error message for this, though it doesn't >> >> increase the counter of the failed tests. >> >> >> > Thanks for persevering with this! Although this patch definitely fixes the >> > panic I was seeing, I now observe buffer verification failures in subsequent >> > test runs after an aborted run: >> >> I think the description to the commit adfa543e "dmatest: don't use >> set_freezable_with_signal()" may shed light on this. >> >> The background (if I got it correctly) is in race with done flag. So, >> we got a callback call from the DMA engine, but we don't know which >> transfer triggers it. >> I might be wrong. This is just an assumption. >> >> Have you ever see such behaviour on pre v3.10-rc1 kernels? (I mean >> with old dmatest module) > Terminate shouldnt cause the issue with buffer verfication, can you try this on > dw_dmac, do you see similar failures on verfication?
I saw the similar errors on dw_dmac on Intel Medfield device. Anyway, I checked another approach with Will. For now I will send a quick fix that prevents tester to abort an ongoing transfer. In future we could implement a robust logic when transfers can be interrupted at any time.
-- With Best Regards, Andy Shevchenko
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