drm/msm: Fix debugfs deadlock

In normal cases the gem obj lock is acquired first before mm_lock.  The
exception is iterating the various object lists.  In the shrinker path,
deadlock is avoided by using msm_gem_trylock() and skipping over objects
that cannot be locked.  But for debugfs the straightforward thing is to
split things out into a separate list of all objects protected by it's
own lock.

Fixes: d984457b31c4 ("drm/msm: Add priv->mm_lock to protect active/inactive lists")
Signed-off-by: Rob Clark <robdclark@chromium.org>
Tested-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20210401012722.527712-4-robdclark@gmail.com
Signed-off-by: Rob Clark <robdclark@chromium.org>

1 files changed, 3 insertions, 11 deletions

diff --git a/drivers/gpu/drm/msm/msm_debugfs.c b/drivers/gpu/drm/msm/msm_debugfs.c
index 85ad0babc326..d611cc8e54a4 100644
--- a/drivers/gpu/drm/msm/msm_debugfs.c
+++ b/drivers/gpu/drm/msm/msm_debugfs.c
@@ -111,23 +111,15 @@ static const struct file_operations msm_gpu_fops = {
 static int msm_gem_show(struct drm_device *dev, struct seq_file *m)
 {
 	struct msm_drm_private *priv = dev->dev_private;
-	struct msm_gpu *gpu = priv->gpu;
 	int ret;
 
-	ret = mutex_lock_interruptible(&priv->mm_lock);
+	ret = mutex_lock_interruptible(&priv->obj_lock);
 	if (ret)
 		return ret;
 
-	if (gpu) {
-		seq_printf(m, "Active Objects (%s):\n", gpu->name);
-		msm_gem_describe_objects(&gpu->active_list, m);
-	}
-
-	seq_printf(m, "Inactive Objects:\n");
-	msm_gem_describe_objects(&priv->inactive_dontneed, m);
-	msm_gem_describe_objects(&priv->inactive_willneed, m);
+	msm_gem_describe_objects(&priv->objects, m);
 
-	mutex_unlock(&priv->mm_lock);
+	mutex_unlock(&priv->obj_lock);
 
 	return 0;
 }