linux-kernel - Re: [PATCH v3 4/8] DMA: Freescale: add fsl_dma_free

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Message-ID: <1397482830.11914.126.camel@smile.fi.intel.com>
Date:	Mon, 14 Apr 2014 16:40:30 +0300
From:	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:	Hongbo Zhang <hongbo.zhang@...escale.com>
Cc:	vkoul@...radead.org, dan.j.williams@...el.com,
	dmaengine@...r.kernel.org, scottwood@...escale.com,
	leo.li@...escale.com, linuxppc-dev@...ts.ozlabs.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 4/8] DMA: Freescale: add fsl_dma_free_descriptor() to
 reduce code duplication

On Fri, 2014-04-11 at 16:14 +0800, Hongbo Zhang wrote:
> On 04/10/2014 07:29 PM, Andy Shevchenko wrote:
> > On Thu, 2014-04-10 at 15:10 +0800, hongbo.zhang@...escale.com wrote:

[]

> >> @@ -819,8 +826,7 @@ static void fsldma_cleanup_descriptor(struct fsldma_chan *chan,
> >>   	dma_run_dependencies(txd);
> >>   
> >>   	dma_descriptor_unmap(txd);
> >> -	chan_dbg(chan, "LD %p free\n", desc);
> >> -	dma_pool_free(chan->desc_pool, desc, txd->phys);
> >> +	fsl_dma_free_descriptor(chan, desc);
> > Here is no list_del() call since it's been called in dma_do_tasklet().
> > What will be the result of double list_del() against the same node?
> 
> Not clear with your point.
> This patch is only introducing a common fsl_dma_free_descriptor() to 
> reduce code duplication. And later in the patch 6/8 the 
> fsldma_cleanup_descriptor() is replaced by fsldma_cleanup_descriptorS().

In the last case you could have a broken kernel which will fails on
double list_del(). I think it's better to leave this one untouched and
you may remove it later.

Or move this patch after you have removed that lines.

-- 
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Intel Finland Oy

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