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

["Nirujogi, Pratap" <pnirujog@amd.com>]

On 6/29/2026 7:30 AM, Ricardo Ribalda wrote:
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> 
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> 
> 
> 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