Messages in this thread | | | Date | Fri, 18 Apr 2014 11:34:50 -0500 | From | Joel Fernandes <> | Subject | Re: [PATCH] [FIX] dmaengine: virt-dma: Free descriptor after callback |
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On 04/18/2014 03:50 AM, Russell King - ARM Linux wrote: > On Thu, Apr 17, 2014 at 07:56:50PM -0500, Joel Fernandes wrote: >> Free the vd (virt descriptor) after the callback is called. In EDMA driver >> atleast which uses virt-dma, we make use of the desc during the callback and if >> its dangerously freed before the callback is called. I also noticed this in >> omap-dma dmaengine driver. > > You've missed the vital bit of information: why do you make use of the > descriptor afterwards? You shouldn't. omap-dma doesn't either. > > Once clients submit their request to DMA engine, they must not hold any > kind of reference to the descriptor other than the cookie. >
Sorry, I confused edma/omap-dma callbacks for virt dma callbacks.
Anyway, I think there is still a chance in edma that we refer to the echan->edesc pointer later on after virt-dma calls the free (in edma_execute), so I'll just NULL that out to be safe and submit a patch. Thanks.
regards, -Joel
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