[PATCH v9 24/26] drm/xe: forcewake debugfs open fails on xe_forcewake_get failure

[Nilawar, Badal]

On 14-10-2024 13:25, Himal Prasad Ghimiray wrote:
> A failure in xe_force_wake_get() no longer increments the domain's
> refcount. Therefore, if xe_force_wake_get() fails during forcewake
> debugfs open, return an error. This ensures there are no valid file
> descriptors to close via forcewake debugfs, preventing refcount
> mismanagement.
> 
> v3
> - return xe_wakeref_t instead of int in xe_force_wake_get()
> 
> v5
> - return unsigned int from xe_force_wake_get()
> 
> v6
> - Use helper xe_force_wake_ref_has_domain()
> to determine the status of the call.
> 
> Cc: Badal Nilawar <badal.nilawar at intel.com>
> Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
> Cc: Lucas De Marchi <lucas.demarchi at intel.com>
> Signed-off-by: Himal Prasad Ghimiray <himal.prasad.ghimiray at intel.com>
> ---
>   drivers/gpu/drm/xe/xe_debugfs.c | 27 +++++++++++++++++++++++----
>   1 file changed, 23 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_debugfs.c b/drivers/gpu/drm/xe/xe_debugfs.c
> index fe4319eb13fd..492b4877433f 100644
> --- a/drivers/gpu/drm/xe/xe_debugfs.c
> +++ b/drivers/gpu/drm/xe/xe_debugfs.c
> @@ -90,13 +90,32 @@ static int forcewake_open(struct inode *inode, struct file *file)
>   {
>   	struct xe_device *xe = inode->i_private;
>   	struct xe_gt *gt;
> -	u8 id;
> +	u8 id, last_gt;
> +	unsigned int fw_ref;
>   
>   	xe_pm_runtime_get(xe);
> -	for_each_gt(gt, xe, id)
> -		XE_WARN_ON(xe_force_wake_get(gt_to_fw(gt), XE_FORCEWAKE_ALL));
> +	for_each_gt(gt, xe, id) {
> +		last_gt = id;
> +
> +		fw_ref = xe_force_wake_get(gt_to_fw(gt), XE_FORCEWAKE_ALL);
> +		if (!xe_force_wake_ref_has_domain(fw_ref, XE_FORCEWAKE_ALL))
> +			goto err_fw_get;
> +	}
>   
>   	return 0;
> +
> +err_fw_get:
> +	for_each_gt(gt, xe, id) {
> +		if (id < last_gt)
> +			xe_force_wake_put(gt_to_fw(gt), XE_FORCEWAKE_ALL);
> +		else if (id == last_gt)
> +			xe_force_wake_put(gt_to_fw(gt), fw_ref);
> +		else
> +			break;
> +	}
> +
> +	xe_pm_runtime_put(xe);
> +	return -ETIMEDOUT;
>   }
>   
>   static int forcewake_release(struct inode *inode, struct file *file)
> @@ -106,7 +125,7 @@ static int forcewake_release(struct inode *inode, struct file *file)
>   	u8 id;
>   
>   	for_each_gt(gt, xe, id)
> -		XE_WARN_ON(xe_force_wake_put(gt_to_fw(gt), XE_FORCEWAKE_ALL));
> +		xe_force_wake_put(gt_to_fw(gt), XE_FORCEWAKE_ALL);

LGTM
Reviewed-by: Badal Nilawar <badal.nilawar at intel.com>

Regards,
Badal

>   	xe_pm_runtime_put(xe);
>   
>   	return 0;