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 -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
