Date: Fri, 18 Apr 2014 09:50:19 +0100
From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Joel Fernandes <joelf@ti.com>
Cc: dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-omap@vger.kernel.org,
        davinci-linux-open-source@linux.davincidsp.com,
        Vinod Koul <vinod.koul@intel.com>,
        Dan Williams <dan.j.williams@intel.com>
Subject: Re: [PATCH] [FIX] dmaengine: virt-dma: Free descriptor after
	callback
Message-ID: <20140418085019.GN27282@n2100.arm.linux.org.uk>
References: <1397782610-7370-1-git-send-email-joelf@ti.com>
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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.

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