[PATCH 1/1] coresight: trbe: Fix return value check in arm_trbe_register_coresight_cpu()

[PATCH 1/1] coresight: trbe: Fix return value check in arm_trbe_register_coresight_cpu()

[Zhen Lei]

Function devm_kzalloc() returns NULL instead of ERR_PTR() when it fails.
The IS_ERR() test in the return value check should be replaced with NULL
test.

Fixes: 39744738a67d ("coresight: trbe: Allocate platform data per device")
Fixes: 3fbf7f011f24 ("coresight: sink: Add TRBE driver")
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
---
 drivers/hwtracing/coresight/coresight-trbe.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c
index 96a32b213669940..93fe9860acf16bd 100644
--- a/drivers/hwtracing/coresight/coresight-trbe.c
+++ b/drivers/hwtracing/coresight/coresight-trbe.c
@@ -1266,7 +1266,7 @@ static void arm_trbe_register_coresight_cpu(struct trbe_drvdata *drvdata, int cp
 	 * into the device for that purpose.
 	 */
 	desc.pdata = devm_kzalloc(dev, sizeof(*desc.pdata), GFP_KERNEL);
-	if (IS_ERR(desc.pdata))
+	if (!desc.pdata)
 		goto cpu_clear;
 
 	desc.type = CORESIGHT_DEV_TYPE_SINK;
-- 
2.34.1

Re: [PATCH 1/1] coresight: trbe: Fix return value check in arm_trbe_register_coresight_cpu()

[James Clark]

On 18/10/2024 3:08 pm, Zhen Lei wrote:
> Function devm_kzalloc() returns NULL instead of ERR_PTR() when it fails.
> The IS_ERR() test in the return value check should be replaced with NULL
> test.
> 
> Fixes: 39744738a67d ("coresight: trbe: Allocate platform data per device")
> Fixes: 3fbf7f011f24 ("coresight: sink: Add TRBE driver")

I don't think the code that this patches exists in 3fbf7f011f24, but it 
looks ok for 39744738a67d.

> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
> ---
>   drivers/hwtracing/coresight/coresight-trbe.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c
> index 96a32b213669940..93fe9860acf16bd 100644
> --- a/drivers/hwtracing/coresight/coresight-trbe.c
> +++ b/drivers/hwtracing/coresight/coresight-trbe.c
> @@ -1266,7 +1266,7 @@ static void arm_trbe_register_coresight_cpu(struct trbe_drvdata *drvdata, int cp
>   	 * into the device for that purpose.
>   	 */
>   	desc.pdata = devm_kzalloc(dev, sizeof(*desc.pdata), GFP_KERNEL);
> -	if (IS_ERR(desc.pdata))
> +	if (!desc.pdata)
>   		goto cpu_clear;
>   
>   	desc.type = CORESIGHT_DEV_TYPE_SINK;


Reviewed-by: James Clark <james.clark@linaro.org>

Re: [PATCH] coresight: trbe: Fix return value check in arm_trbe_register_coresight_cpu()

[Markus Elfring]

…
> The IS_ERR() test in the return value check should be replaced with NULL test.
…

How do you think about to convert such a change description into
an imperative wording?
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst?h=v6.12-rc3#n94

Regards,
Markus

Re: [PATCH 1/1] coresight: trbe: Fix return value check in arm_trbe_register_coresight_cpu()

[Anshuman Khandual]

On 10/18/24 19:38, Zhen Lei wrote:
> Function devm_kzalloc() returns NULL instead of ERR_PTR() when it fails.

Right, devm_kzalloc() calls devm_kmalloc() with additional __GFP_ZERO which
returns NULL on error.

> The IS_ERR() test in the return value check should be replaced with NULL
> test.
> 
> Fixes: 39744738a67d ("coresight: trbe: Allocate platform data per device")
> Fixes: 3fbf7f011f24 ("coresight: sink: Add TRBE driver")

Actually this problem is caused by the following commit which had replaced
coresight_get_platform_data() with devm_kzalloc() for a dummy 'desc.pdata'
allocation. Earlier IS_ERR() test for the return value, was correct for
coresight_get_platform_data() which returns ERR_PTR() on error, but then
it should have been changed for devm_kzalloc() into a NULL check instead.

4277f035d227 ("coresight: trbe: Add a representative coresight_platform_data for TRBE")

Please add "Fixes:" tag for the above commit instead.

> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
> ---
>  drivers/hwtracing/coresight/coresight-trbe.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c
> index 96a32b213669940..93fe9860acf16bd 100644
> --- a/drivers/hwtracing/coresight/coresight-trbe.c
> +++ b/drivers/hwtracing/coresight/coresight-trbe.c
> @@ -1266,7 +1266,7 @@ static void arm_trbe_register_coresight_cpu(struct trbe_drvdata *drvdata, int cp
>  	 * into the device for that purpose.
>  	 */
>  	desc.pdata = devm_kzalloc(dev, sizeof(*desc.pdata), GFP_KERNEL);
> -	if (IS_ERR(desc.pdata))
> +	if (!desc.pdata)
>  		goto cpu_clear;
>  
>  	desc.type = CORESIGHT_DEV_TYPE_SINK;

Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>

Re: [PATCH 1/1] coresight: trbe: Fix return value check in arm_trbe_register_coresight_cpu()

[Leizhen (ThunderTown)]

On 2024/10/21 10:58, Anshuman Khandual wrote:
> 
> 
> On 10/18/24 19:38, Zhen Lei wrote:
>> Function devm_kzalloc() returns NULL instead of ERR_PTR() when it fails.
> 
> Right, devm_kzalloc() calls devm_kmalloc() with additional __GFP_ZERO which
> returns NULL on error.
> 
>> The IS_ERR() test in the return value check should be replaced with NULL
>> test.
>>
>> Fixes: 39744738a67d ("coresight: trbe: Allocate platform data per device")
>> Fixes: 3fbf7f011f24 ("coresight: sink: Add TRBE driver")
> 
> Actually this problem is caused by the following commit which had replaced
> coresight_get_platform_data() with devm_kzalloc() for a dummy 'desc.pdata'
> allocation. Earlier IS_ERR() test for the return value, was correct for
> coresight_get_platform_data() which returns ERR_PTR() on error, but then
> it should have been changed for devm_kzalloc() into a NULL check instead.
> 
> 4277f035d227 ("coresight: trbe: Add a representative coresight_platform_data for TRBE")
> 
> Please add "Fixes:" tag for the above commit instead.

Yes, you're right. In retrospect, I probably found 3fbf7f011f24 just by
searching for IS_ERR(). I will update and post v2. Thanks.

> 
>> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
>> ---
>>  drivers/hwtracing/coresight/coresight-trbe.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c
>> index 96a32b213669940..93fe9860acf16bd 100644
>> --- a/drivers/hwtracing/coresight/coresight-trbe.c
>> +++ b/drivers/hwtracing/coresight/coresight-trbe.c
>> @@ -1266,7 +1266,7 @@ static void arm_trbe_register_coresight_cpu(struct trbe_drvdata *drvdata, int cp
>>  	 * into the device for that purpose.
>>  	 */
>>  	desc.pdata = devm_kzalloc(dev, sizeof(*desc.pdata), GFP_KERNEL);
>> -	if (IS_ERR(desc.pdata))
>> +	if (!desc.pdata)
>>  		goto cpu_clear;
>>  
>>  	desc.type = CORESIGHT_DEV_TYPE_SINK;
> 
> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
> 
> .
> 

-- 
Regards,
  Zhen Lei