From: Christian Gmeiner <cgmeiner@igalia.com>

If the active performance monitor (v3d->active_perfmon) is being
destroyed, stop it first. Currently, the active perfmon is not
stopped during destruction, leaving the v3d->active_perfmon pointer
stale. This can lead to undefined behavior and instability.

This patch ensures that the active perfmon is stopped before being
destroyed, aligning with the behavior introduced in commit
7d1fd3638ee3 ("drm/v3d: Stop the active perfmon before being destroyed").

Cc: stable@vger.kernel.org # v5.15+
Fixes: 26a4dc29b74a ("drm/v3d: Expose performance counters to userspace")
Signed-off-by: Christian Gmeiner <cgmeiner@igalia.com>
---
 drivers/gpu/drm/v3d/v3d_perfmon.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/v3d/v3d_perfmon.c b/drivers/gpu/drm/v3d/v3d_perfmon.c
index 00cd081d7873..909288d43f2f 100644
--- a/drivers/gpu/drm/v3d/v3d_perfmon.c
+++ b/drivers/gpu/drm/v3d/v3d_perfmon.c
@@ -383,6 +383,7 @@ int v3d_perfmon_destroy_ioctl(struct drm_device *dev, void *data,
 {
 	struct v3d_file_priv *v3d_priv = file_priv->driver_priv;
 	struct drm_v3d_perfmon_destroy *req = data;
+	struct v3d_dev *v3d = v3d_priv->v3d;
 	struct v3d_perfmon *perfmon;
 
 	mutex_lock(&v3d_priv->perfmon.lock);
@@ -392,6 +393,10 @@ int v3d_perfmon_destroy_ioctl(struct drm_device *dev, void *data,
 	if (!perfmon)
 		return -EINVAL;
 
+	/* If the active perfmon is being destroyed, stop it first */
+	if (perfmon == v3d->active_perfmon)
+		v3d_perfmon_stop(v3d, perfmon, false);
+
 	v3d_perfmon_put(perfmon);
 
 	return 0;
-- 
2.47.0

Hi Christian,

On 18/11/24 19:19, Christian Gmeiner wrote:
> From: Christian Gmeiner <cgmeiner@igalia.com>
> 
> If the active performance monitor (v3d->active_perfmon) is being
> destroyed, stop it first. Currently, the active perfmon is not
> stopped during destruction, leaving the v3d->active_perfmon pointer
> stale. This can lead to undefined behavior and instability.
> 
> This patch ensures that the active perfmon is stopped before being
> destroyed, aligning with the behavior introduced in commit
> 7d1fd3638ee3 ("drm/v3d: Stop the active perfmon before being destroyed").
> 
> Cc: stable@vger.kernel.org # v5.15+
> Fixes: 26a4dc29b74a ("drm/v3d: Expose performance counters to userspace")
> Signed-off-by: Christian Gmeiner <cgmeiner@igalia.com>

Applied to misc/kernel.git (drm-misc-next).

Maxime, Thomas, if possible, could you cherry-pick this commit to be 
included in 6.13? Thanks!

Best Regards,
- Maíra

> ---
>   drivers/gpu/drm/v3d/v3d_perfmon.c | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/gpu/drm/v3d/v3d_perfmon.c b/drivers/gpu/drm/v3d/v3d_perfmon.c
> index 00cd081d7873..909288d43f2f 100644
> --- a/drivers/gpu/drm/v3d/v3d_perfmon.c
> +++ b/drivers/gpu/drm/v3d/v3d_perfmon.c
> @@ -383,6 +383,7 @@ int v3d_perfmon_destroy_ioctl(struct drm_device *dev, void *data,
>   {
>   	struct v3d_file_priv *v3d_priv = file_priv->driver_priv;
>   	struct drm_v3d_perfmon_destroy *req = data;
> +	struct v3d_dev *v3d = v3d_priv->v3d;
>   	struct v3d_perfmon *perfmon;
>   
>   	mutex_lock(&v3d_priv->perfmon.lock);
> @@ -392,6 +393,10 @@ int v3d_perfmon_destroy_ioctl(struct drm_device *dev, void *data,
>   	if (!perfmon)
>   		return -EINVAL;
>   
> +	/* If the active perfmon is being destroyed, stop it first */
> +	if (perfmon == v3d->active_perfmon)
> +		v3d_perfmon_stop(v3d, perfmon, false);
> +
>   	v3d_perfmon_put(perfmon);
>   
>   	return 0;