2016-10-19 15:41:08

by Arnd Bergmann

Subject: [PATCH] dmaengine: st_fdma: fix uninitialized variable access

The newly added st_fdma driver introduces a build warning for
allmodconfig when we add '-Wmaybe-uninitialized':

drivers/dma/st_fdma.c: In function 'st_fdma_probe':
drivers/dma/st_fdma.c:777:5: error: 'ret' may be used uninitialized in this function [-Werror=maybe-uninitialized]

The warning is correct, though this can't happen in practice
as the check is redundant (we don't get to this function if
the pointer is NULL). Even if the function were called with a
NULL of_node, the check is not needed because of_property_read_u32
can deal with a NULL argument by returning an error.

Removing the unnecessary code simplifies the function and avoids
the condition that we get the warning for.

Fixes: 6b4cd727eaf1 ("dmaengine: st_fdma: Add STMicroelectronics FDMA engine driver support")
Signed-off-by: Arnd Bergmann <[email protected]>
---
drivers/dma/st_fdma.c | 14 ++------------
1 file changed, 2 insertions(+), 12 deletions(-)

diff --git a/drivers/dma/st_fdma.c b/drivers/dma/st_fdma.c
index 515e1d4c43e8..232d3547a6a3 100644
--- a/drivers/dma/st_fdma.c
+++ b/drivers/dma/st_fdma.c
@@ -720,21 +720,11 @@ static int st_fdma_parse_dt(struct platform_device *pdev,
const struct st_fdma_driverdata *drvdata,
struct st_fdma_dev *fdev)
{
- struct device_node *np = pdev->dev.of_node;
- int ret;
-
- if (!np)
- goto err;
-
- ret = of_property_read_u32(np, "dma-channels", &fdev->nr_channels);
- if (ret)
- goto err;
-
snprintf(fdev->fw_name, FW_NAME_SIZE, "fdma_%s_%d.elf",
drvdata->name, drvdata->id);

-err:
- return ret;
+ return of_property_read_u32(pdev->dev.of_node, "dma-channels",
+ &fdev->nr_channels);
}
#define FDMA_DMA_BUSWIDTHS (BIT(DMA_SLAVE_BUSWIDTH_1_BYTE) | \
BIT(DMA_SLAVE_BUSWIDTH_2_BYTES) | \
--
2.9.0

2016-10-19 14:32:09

by Peter Griffin

Subject: Re: [PATCH] dmaengine: st_fdma: fix uninitialized variable access

Hi Arnd,

On Wed, 19 Oct 2016, Arnd Bergmann wrote:

> The newly added st_fdma driver introduces a build warning for
> allmodconfig when we add '-Wmaybe-uninitialized':
>
> drivers/dma/st_fdma.c: In function 'st_fdma_probe':
> drivers/dma/st_fdma.c:777:5: error: 'ret' may be used uninitialized in this function [-Werror=maybe-uninitialized]
>
> The warning is correct, though this can't happen in practice
> as the check is redundant (we don't get to this function if
> the pointer is NULL). Even if the function were called with a
> NULL of_node, the check is not needed because of_property_read_u32
> can deal with a NULL argument by returning an error.
>
> Removing the unnecessary code simplifies the function and avoids
> the condition that we get the warning for.
>
> Fixes: 6b4cd727eaf1 ("dmaengine: st_fdma: Add STMicroelectronics FDMA engine driver support")
> Signed-off-by: Arnd Bergmann <[email protected]>
> ---

Acked-by: Peter Griffin <[email protected]>

regards,

Peter.

2016-10-19 14:32:48

by Vinod Koul

Subject: Re: [PATCH] dmaengine: st_fdma: fix uninitialized variable access

On Wed, Oct 19, 2016 at 02:09:10PM +0200, Arnd Bergmann wrote:
> The newly added st_fdma driver introduces a build warning for
> allmodconfig when we add '-Wmaybe-uninitialized':
>
> drivers/dma/st_fdma.c: In function 'st_fdma_probe':
> drivers/dma/st_fdma.c:777:5: error: 'ret' may be used uninitialized in this function [-Werror=maybe-uninitialized]
>
> The warning is correct, though this can't happen in practice
> as the check is redundant (we don't get to this function if
> the pointer is NULL). Even if the function were called with a
> NULL of_node, the check is not needed because of_property_read_u32
> can deal with a NULL argument by returning an error.
>
> Removing the unnecessary code simplifies the function and avoids
> the condition that we get the warning for.

Applied, thanks

--
~Vinod