linux-kernel - [PATCH] drm/v3d: Stop active perfmon if it is being destroyed

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Message-ID: <20241118221948.1758130-1-christian.gmeiner@gmail.com>
Date: Mon, 18 Nov 2024 23:19:47 +0100
From: Christian Gmeiner <christian.gmeiner@...il.com>
To: Melissa Wen <mwen@...lia.com>,
	Maíra Canal <mcanal@...lia.com>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>,
	"Juan A. Suarez Romero" <jasuarez@...lia.com>
Cc: kernel-dev@...lia.com,
	Christian Gmeiner <cgmeiner@...lia.com>,
	stable@...r.kernel.org,
	dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] drm/v3d: Stop active perfmon if it is being destroyed

From: Christian Gmeiner <cgmeiner@...lia.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@...r.kernel.org # v5.15+
Fixes: 26a4dc29b74a ("drm/v3d: Expose performance counters to userspace")
Signed-off-by: Christian Gmeiner <cgmeiner@...lia.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