Re: [PATCH 5/9] media: platform: amd: use refcount_t instead of atomic_t

[Bin Du <Bin.Du@amd.com>]

On 6/29/2026 11:51 PM, Nirujogi, Pratap wrote:
> 
> 
> On 6/29/2026 7:30 AM, Ricardo Ribalda wrote:
>> [You don't often get email from ribalda@chromium.org. Learn why this
>> is important at https://aka.ms/LearnAboutSenderIdentification ]
>>
>> Caution: This message originated from an External Source. Use proper
>> caution when opening attachments, clicking links, or responding.
>>
>>
>> We are using the refcnt variable for refcounting. Use the refcount_t
>> type instead, as it has support for saturation and underflow.
>>
>> This also makes cocci happier, as it will fix the following warning:
>> ./platform/amd/isp4/isp4_subdev.c:394:6-25: WARNING:
>> atomic_dec_and_test variation before object free at line 395.
>>
>> Fixes: 4c5feef6a62c ("media: platform: amd: Add isp4 fw and hw
>> interface")
>> Cc: stable@vger.kernel.org
>> Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
>> ---
>>   drivers/media/platform/amd/isp4/isp4_interface.c | 4 ++--
>>   drivers/media/platform/amd/isp4/isp4_interface.h | 2 +-
>>   drivers/media/platform/amd/isp4/isp4_subdev.c    | 2 +-
>>   3 files changed, 4 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/media/platform/amd/isp4/isp4_interface.c b/
>> drivers/media/platform/amd/isp4/isp4_interface.c
>> index 8d73f66bb42c..00a817909292 100644
>> --- a/drivers/media/platform/amd/isp4/isp4_interface.c
>> +++ b/drivers/media/platform/amd/isp4/isp4_interface.c
>> @@ -375,7 +375,7 @@ static int isp4if_send_fw_cmd(struct
>> isp4_interface *ispif, u32 cmd_id,
>>                          return -ENOMEM;
>>
>>                  /* Get two references: one for the resp thread, one
>> for us */
>> -               atomic_set(&ele->refcnt, 2);
>> +               refcount_set(&ele->refcnt, 2);
>>                  init_completion(&ele->cmd_done);
>>          }
>>
>> @@ -455,7 +455,7 @@ static int isp4if_send_fw_cmd(struct
>> isp4_interface *ispif, u32 cmd_id,
>>
>>   put_ele_ref:
>>          /* Don't free the command if we didn't put the last reference */
>> -       if (ele && atomic_dec_return(&ele->refcnt))
>> +       if (ele && !refcount_dec_and_test(&ele->refcnt))
>>                  ele = NULL;
>>
>>   free_ele:
>> diff --git a/drivers/media/platform/amd/isp4/isp4_interface.h b/
>> drivers/media/platform/amd/isp4/isp4_interface.h
>> index ce3ac9b9e5cd..04db71cd54e6 100644
>> --- a/drivers/media/platform/amd/isp4/isp4_interface.h
>> +++ b/drivers/media/platform/amd/isp4/isp4_interface.h
>> @@ -68,7 +68,7 @@ struct isp4if_cmd_element {
>>          u32 seq_num;
>>          u32 cmd_id;
>>          struct completion cmd_done;
>> -       atomic_t refcnt;
>> +       refcount_t refcnt;
>>   };
>>
>>   struct isp4_interface {
>> diff --git a/drivers/media/platform/amd/isp4/isp4_subdev.c b/drivers/
>> media/platform/amd/isp4/isp4_subdev.c
>> index 48deea79ce6c..2a8bc1207843 100644
>> --- a/drivers/media/platform/amd/isp4/isp4_subdev.c
>> +++ b/drivers/media/platform/amd/isp4/isp4_subdev.c
>> @@ -391,7 +391,7 @@ static void isp4sd_fw_resp_cmd_done(struct
>> isp4_subdev *isp_subdev,
>>
>>          if (ele) {
>>                  complete(&ele->cmd_done);
>> -               if (atomic_dec_and_test(&ele->refcnt))
>> +               if (refcount_dec_and_test(&ele->refcnt))
>>                          kfree(ele);
>>          }
>>   }
>>
>> -- 
>> 2.55.0.rc0.799.gd6f94ed593-goog
>>
> 
> Reviewed-by: Pratap Nirujogi <pratap.nirujogi@amd.com>
> 
> Thanks,
> Pratap
> 
> 

Reviewed-by: Bin Du <bin.du@amd.com>

Regards,
Bin