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

[Anshuman Khandual <anshuman.khandual@arm.com>]

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>