On Fri, Apr 18, 2014 at 11:34:50AM -0500, Joel Fernandes wrote: > 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. Yes, that would be the right way :) While looking at this, I see it is not called out specfically in documentation, will update that as well -- ~Vinod -- 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
