[PATCH] spi: rockchip: fix warning of static check

[PATCH] spi: rockchip: fix warning of static check

[Shawn Lin]

Let's improve the check with -EPROBE_DEFER, otherwise
we may pass on null pointer to PTR_ERR. That causes the
static checker warning: passing zero to 'PTR_ERR'.

Reported-by: Dan Carpenter <dan.carpenter-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
Cc: Doug Anderson <dianders-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
Cc: Dan Carpenter <dan.carpenter-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
Signed-off-by: Shawn Lin <shawn.lin-TNX95d0MmH7DzftRWevZcw@public.gmane.org>
---

 drivers/spi/spi-rockchip.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/spi/spi-rockchip.c b/drivers/spi/spi-rockchip.c
index bfeb0d4..2cb36d9 100644
--- a/drivers/spi/spi-rockchip.c
+++ b/drivers/spi/spi-rockchip.c
@@ -726,20 +726,24 @@ static int rockchip_spi_probe(struct platform_device *pdev)
 	rs->dma_tx.ch = dma_request_slave_channel(rs->dev, "tx");
 	if (IS_ERR_OR_NULL(rs->dma_tx.ch)) {
 		/* Check tx to see if we need defer probing driver */
-		if (PTR_ERR(rs->dma_tx.ch) == -EPROBE_DEFER) {
+		if (rs->dma_tx.ch == ERR_PTR(-EPROBE_DEFER)) {
 			ret = -EPROBE_DEFER;
 			goto err_get_fifo_len;
 		}
 		dev_warn(rs->dev, "Failed to request TX DMA channel\n");
+		rs->dma_tx.ch = NULL;
 	}
 
 	rs->dma_rx.ch = dma_request_slave_channel(rs->dev, "rx");
-	if (!rs->dma_rx.ch) {
-		if (rs->dma_tx.ch) {
+	if (IS_ERR_OR_NULL(rs->dma_rx.ch)) {
+		if (rs->dma_tx.ch == ERR_PTR(-EPROBE_DEFER)) {
 			dma_release_channel(rs->dma_tx.ch);
 			rs->dma_tx.ch = NULL;
+			ret = -EPROBE_DEFER;
+			goto err_get_fifo_len;
 		}
 		dev_warn(rs->dev, "Failed to request RX DMA channel\n");
+		rs->dma_rx.ch = NULL;
 	}
 
 	if (rs->dma_tx.ch && rs->dma_rx.ch) {
-- 
2.3.7


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Re: [PATCH] spi: rockchip: fix warning of static check

[Vladimir Zapolskiy]

Hi Shawn,

On 22.03.2016 13:36, Shawn Lin wrote:
> Let's improve the check with -EPROBE_DEFER, otherwise
> we may pass on null pointer to PTR_ERR. That causes the
> static checker warning: passing zero to 'PTR_ERR'.
> 
> Reported-by: Dan Carpenter <dan.carpenter-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
> Cc: Doug Anderson <dianders-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
> Cc: Dan Carpenter <dan.carpenter-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
> Signed-off-by: Shawn Lin <shawn.lin-TNX95d0MmH7DzftRWevZcw@public.gmane.org>
> ---
> 
>  drivers/spi/spi-rockchip.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/spi/spi-rockchip.c b/drivers/spi/spi-rockchip.c
> index bfeb0d4..2cb36d9 100644
> --- a/drivers/spi/spi-rockchip.c
> +++ b/drivers/spi/spi-rockchip.c
> @@ -726,20 +726,24 @@ static int rockchip_spi_probe(struct platform_device *pdev)
>  	rs->dma_tx.ch = dma_request_slave_channel(rs->dev, "tx");
>  	if (IS_ERR_OR_NULL(rs->dma_tx.ch)) {
>  		/* Check tx to see if we need defer probing driver */
> -		if (PTR_ERR(rs->dma_tx.ch) == -EPROBE_DEFER) {
> +		if (rs->dma_tx.ch == ERR_PTR(-EPROBE_DEFER)) {

won't it be easier to change dma_request_slave_channel() to
dma_request_chan() or dma_request_slave_channel_reason() and replace strange
IS_ERR_OR_NULL() check with IS_ERR() one?

AFAIU that's almost what has been suggested by Doug and it is a better
fix than this one published.

At the moment check for IS_ERR_OR_NULL() is too aggressive and quite
confusing, because dma_request_slave_channel() never returns NULL.

>  			ret = -EPROBE_DEFER;
>  			goto err_get_fifo_len;
>  		}
>  		dev_warn(rs->dev, "Failed to request TX DMA channel\n");
> +		rs->dma_tx.ch = NULL;
>  	}
>  
>  	rs->dma_rx.ch = dma_request_slave_channel(rs->dev, "rx");
> -	if (!rs->dma_rx.ch) {
> -		if (rs->dma_tx.ch) {
> +	if (IS_ERR_OR_NULL(rs->dma_rx.ch)) {
> +		if (rs->dma_tx.ch == ERR_PTR(-EPROBE_DEFER)) {

Same as above.

>  			dma_release_channel(rs->dma_tx.ch);
>  			rs->dma_tx.ch = NULL;
> +			ret = -EPROBE_DEFER;
> +			goto err_get_fifo_len;
>  		}
>  		dev_warn(rs->dev, "Failed to request RX DMA channel\n");
> +		rs->dma_rx.ch = NULL;
>  	}
>  
>  	if (rs->dma_tx.ch && rs->dma_rx.ch) {
> 

--
With best wishes,
Vladimir
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Re: [PATCH] spi: rockchip: fix warning of static check

[Vladimir Zapolskiy]

On 22.03.2016 14:56, Vladimir Zapolskiy wrote:
> Hi Shawn,
> 
> On 22.03.2016 13:36, Shawn Lin wrote:
>> Let's improve the check with -EPROBE_DEFER, otherwise
>> we may pass on null pointer to PTR_ERR. That causes the
>> static checker warning: passing zero to 'PTR_ERR'.
>>
>> Reported-by: Dan Carpenter <dan.carpenter-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
>> Cc: Doug Anderson <dianders-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
>> Cc: Dan Carpenter <dan.carpenter-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
>> Signed-off-by: Shawn Lin <shawn.lin-TNX95d0MmH7DzftRWevZcw@public.gmane.org>
>> ---
>>
>>  drivers/spi/spi-rockchip.c | 10 +++++++---
>>  1 file changed, 7 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/spi/spi-rockchip.c b/drivers/spi/spi-rockchip.c
>> index bfeb0d4..2cb36d9 100644
>> --- a/drivers/spi/spi-rockchip.c
>> +++ b/drivers/spi/spi-rockchip.c
>> @@ -726,20 +726,24 @@ static int rockchip_spi_probe(struct platform_device *pdev)
>>  	rs->dma_tx.ch = dma_request_slave_channel(rs->dev, "tx");
>>  	if (IS_ERR_OR_NULL(rs->dma_tx.ch)) {
>>  		/* Check tx to see if we need defer probing driver */
>> -		if (PTR_ERR(rs->dma_tx.ch) == -EPROBE_DEFER) {
>> +		if (rs->dma_tx.ch == ERR_PTR(-EPROBE_DEFER)) {
> 
> won't it be easier to change dma_request_slave_channel() to
> dma_request_chan() or dma_request_slave_channel_reason() and replace strange
> IS_ERR_OR_NULL() check with IS_ERR() one?
> 
> AFAIU that's almost what has been suggested by Doug and it is a better
> fix than this one published.
> 
> At the moment check for IS_ERR_OR_NULL() is too aggressive and quite
> confusing, because dma_request_slave_channel() never returns NULL.

Sorry for a typo, never returns IS_ERR() of course.

>>  			ret = -EPROBE_DEFER;
>>  			goto err_get_fifo_len;
>>  		}
>>  		dev_warn(rs->dev, "Failed to request TX DMA channel\n");
>> +		rs->dma_tx.ch = NULL;
>>  	}
>>  
>>  	rs->dma_rx.ch = dma_request_slave_channel(rs->dev, "rx");
>> -	if (!rs->dma_rx.ch) {
>> -		if (rs->dma_tx.ch) {
>> +	if (IS_ERR_OR_NULL(rs->dma_rx.ch)) {
>> +		if (rs->dma_tx.ch == ERR_PTR(-EPROBE_DEFER)) {
> 
> Same as above.
> 
>>  			dma_release_channel(rs->dma_tx.ch);
>>  			rs->dma_tx.ch = NULL;
>> +			ret = -EPROBE_DEFER;
>> +			goto err_get_fifo_len;
>>  		}
>>  		dev_warn(rs->dev, "Failed to request RX DMA channel\n");
>> +		rs->dma_rx.ch = NULL;
>>  	}
>>  
>>  	if (rs->dma_tx.ch && rs->dma_rx.ch) {
>>
> 

--
With best wishes,
Vladimir

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Re: [PATCH] spi: rockchip: fix warning of static check

[Doug Anderson]

Hi,

On Tue, Mar 22, 2016 at 4:36 AM, Shawn Lin <shawn.lin-TNX95d0MmH7DzftRWevZcw@public.gmane.org> wrote:
> Let's improve the check with -EPROBE_DEFER, otherwise
> we may pass on null pointer to PTR_ERR. That causes the
> static checker warning: passing zero to 'PTR_ERR'.
>
> Reported-by: Dan Carpenter <dan.carpenter-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
> Cc: Doug Anderson <dianders-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
> Cc: Dan Carpenter <dan.carpenter-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
> Signed-off-by: Shawn Lin <shawn.lin-TNX95d0MmH7DzftRWevZcw@public.gmane.org>
> ---
>
>  drivers/spi/spi-rockchip.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/spi/spi-rockchip.c b/drivers/spi/spi-rockchip.c
> index bfeb0d4..2cb36d9 100644
> --- a/drivers/spi/spi-rockchip.c
> +++ b/drivers/spi/spi-rockchip.c
> @@ -726,20 +726,24 @@ static int rockchip_spi_probe(struct platform_device *pdev)
>         rs->dma_tx.ch = dma_request_slave_channel(rs->dev, "tx");

Please change from:
  dma_request_slave_channel()
to:
  dma_request_chan()

The first will never return -EPROBE_DEFER.  The second will.

>         if (IS_ERR_OR_NULL(rs->dma_tx.ch)) {

Once you've changed to dma_request_chan(), change IS_ERR_OR_NULL() to
just IS_ERR().  dma_request_chan() never returns NULL.

>                 /* Check tx to see if we need defer probing driver */
> -               if (PTR_ERR(rs->dma_tx.ch) == -EPROBE_DEFER) {
> +               if (rs->dma_tx.ch == ERR_PTR(-EPROBE_DEFER)) {

Once you've changed to use dma_request_chan(), no need to change this
line.  Leave it as it was.

>                         ret = -EPROBE_DEFER;
>                         goto err_get_fifo_len;
>                 }
>                 dev_warn(rs->dev, "Failed to request TX DMA channel\n");
> +               rs->dma_tx.ch = NULL;
>         }
>
>         rs->dma_rx.ch = dma_request_slave_channel(rs->dev, "rx");
> -       if (!rs->dma_rx.ch) {
> -               if (rs->dma_tx.ch) {
> +       if (IS_ERR_OR_NULL(rs->dma_rx.ch)) {
> +               if (rs->dma_tx.ch == ERR_PTR(-EPROBE_DEFER)) {
>                         dma_release_channel(rs->dma_tx.ch);
>                         rs->dma_tx.ch = NULL;
> +                       ret = -EPROBE_DEFER;
> +                       goto err_get_fifo_len;
>                 }
>                 dev_warn(rs->dev, "Failed to request RX DMA channel\n");
> +               rs->dma_rx.ch = NULL;

Same comments apply to the rx path.
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