Re: [PATCH v3 4/8] DMA: Freescale: add fsl_dma_free_descriptor() to reduce code duplication

[Hongbo Zhang <hongbo.zhang@xxxxxxxxxxxxx>]

On 04/10/2014 07:29 PM, Andy Shevchenko wrote:
> On Thu, 2014-04-10 at 15:10 +0800, hongbo.zhang@xxxxxxxxxxxxx wrote:
> > From: Hongbo Zhang <hongbo.zhang@xxxxxxxxxxxxx>
> >
> > There are several places where descriptors are freed using identical code.
> > This patch puts this code into a function to reduce code duplication.
> >
> > Signed-off-by: Hongbo Zhang <hongbo.zhang@xxxxxxxxxxxxx>
> > Signed-off-by: Qiang Liu <qiang.liu@xxxxxxxxxxxxx>
> > ---
> >   drivers/dma/fsldma.c |   30 ++++++++++++++++++------------
> >   1 file changed, 18 insertions(+), 12 deletions(-)
> >
> > diff --git a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c
> > index b71cc04..b5a0ffa 100644
> > --- a/drivers/dma/fsldma.c
> > +++ b/drivers/dma/fsldma.c
> > @@ -418,6 +418,19 @@ static dma_cookie_t fsl_dma_tx_submit(struct dma_async_tx_descriptor *tx)
> >   }
> >   
> >   /**
> > + * fsl_dma_free_descriptor - Free descriptor from channel's DMA pool.
> > + * @chan : Freescale DMA channel
> > + * @desc: descriptor to be freed
> > + */
> > +static void fsl_dma_free_descriptor(struct fsldma_chan *chan,
> > +		struct fsl_desc_sw *desc)
> > +{
> > +	list_del(&desc->node);
> > +	chan_dbg(chan, "LD %p free\n", desc);
> > +	dma_pool_free(chan->desc_pool, desc, desc->async_tx.phys);
> > +}
> > +
> > +/**
> >    * fsl_dma_alloc_descriptor - Allocate descriptor from channel's DMA pool.
> >    * @chan : Freescale DMA channel
> >    *
> > @@ -489,11 +502,8 @@ static void fsldma_free_desc_list(struct fsldma_chan *chan,
> >   {
> >   	struct fsl_desc_sw *desc, *_desc;
> >   
> > -	list_for_each_entry_safe(desc, _desc, list, node) {
> > -		list_del(&desc->node);
> > -		chan_dbg(chan, "LD %p free\n", desc);
> > -		dma_pool_free(chan->desc_pool, desc, desc->async_tx.phys);
> > -	}
> > +	list_for_each_entry_safe(desc, _desc, list, node)
> > +		fsl_dma_free_descriptor(chan, desc);
> >   }
> >   
> >   static void fsldma_free_desc_list_reverse(struct fsldma_chan *chan,
> > @@ -501,11 +511,8 @@ static void fsldma_free_desc_list_reverse(struct fsldma_chan *chan,
> >   {
> >   	struct fsl_desc_sw *desc, *_desc;
> >   
> > -	list_for_each_entry_safe_reverse(desc, _desc, list, node) {
> > -		list_del(&desc->node);
> > -		chan_dbg(chan, "LD %p free\n", desc);
> > -		dma_pool_free(chan->desc_pool, desc, desc->async_tx.phys);
> > -	}
> > +	list_for_each_entry_safe_reverse(desc, _desc, list, node)
> > +		fsl_dma_free_descriptor(chan, desc);
> >   }
> >   
> >   /**
> > @@ -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().

> >   }
> >   
> >   /**



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