Re: [PATCH v5 4/4] DMA: Freescale: eliminate a compiling warning

From: Scott Wood
Date: Wed Jul 24 2013 - 15:33:53 EST

On 07/24/2013 01:21:09 AM, hongbo.zhang@xxxxxxxxxxxxx wrote:
From: Hongbo Zhang <hongbo.zhang@xxxxxxxxxxxxx>

The variable cookie is initialized in a list_for_each_entry loop, if(unlikely)
the list is empty, this variable will be used uninitialized, so we get a gcc
compiling warning about this. This patch fixes this defect by setting an
initial value to the varialble cookie.

Signed-off-by: Hongbo Zhang <hongbo.zhang@xxxxxxxxxxxxx>
drivers/dma/fsldma.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c
index 16a9a48..14d68a4 100644
--- a/drivers/dma/fsldma.c
+++ b/drivers/dma/fsldma.c
@@ -406,7 +406,7 @@ static dma_cookie_t fsl_dma_tx_submit(struct dma_async_tx_descriptor *tx)
struct fsl_desc_sw *desc = tx_to_fsl_desc(tx);
struct fsl_desc_sw *child;
unsigned long flags;
- dma_cookie_t cookie;
+ dma_cookie_t cookie = 0;

spin_lock_irqsave(&chan->desc_lock, flags);

This patch is unrelated to the rest of the patch series...

What are the semantics of this function if there are multiple entries in the list? Returning the last cookie seems a bit odd.

Is zero the proper error value? include/linux/dmaengine.h suggests that cookies should be < 0 to indicate error.

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