linux-kernel - Re: [PATCH v1 1/5] dma: Add QorIQ qDMA engine driver support

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 18 Aug 2016 10:16:03 +0100
From:	Russell King - ARM Linux <linux@...linux.org.uk>
To:	Yuan Yao <yao.yuan@...escale.com>
Cc:	vinod.koul@...el.com, robh+dt@...nel.org, dan.j.williams@...el.com,
	mark.rutland@....com, shawnguo@...nel.org, leoyang.li@....com,
	dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, Yuan Yao <yao.yuan@....com>
Subject: Re: [PATCH v1 1/5] dma: Add QorIQ qDMA engine driver support

On Thu, Aug 18, 2016 at 02:38:44PM +0800, Yuan Yao wrote:
> +			spin_lock(&fsl_comp->qchan->vchan.lock);
> +			if (status == DMA_COMPLETE)
> +				vchan_cookie_complete(&fsl_comp->vdesc);
> +			fsl_comp->qchan->status = status;

This is buggy - if the DMA has finished processing it, even if it
finished in error, it must _complete_ the transaction.  Completion is
not the same as being successful - it means that the DMA is no longer
processing the cookie.

The issue here is that when the _following_ transaction completes
successfully, _this_ transaction will effectively be marked as complete
due to the way the cookie system works.

So... to get this straight - "completion" means "I have finished
processing this transaction".  It does not mean "I successfully
processed this transaction without any errors."

-- 
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.