drm/msm: Add debugfs to trigger shrinker

Just for the purposes of testing.  Write to it the # of objects to scan,
read back the # freed.

Signed-off-by: Rob Clark <robdclark@chromium.org>
Link: https://lore.kernel.org/r/20210614150618.729610-1-robdclark@gmail.com
Signed-off-by: Rob Clark <robdclark@chromium.org>

drivers/gpu/drm/msm/msm_debugfs.c

@@ -108,6 +108,31 @@ static const struct file_operations msm_gpu_fops = {
 	.release = msm_gpu_release,
 };
 
+static unsigned long last_shrink_freed;
+
+static int
+shrink_get(void *data, u64 *val)
+{
+	*val = last_shrink_freed;
+
+	return 0;
+}
+
+static int
+shrink_set(void *data, u64 val)
+{
+	struct drm_device *dev = data;
+
+	last_shrink_freed = msm_gem_shrinker_shrink(dev, val);
+
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(shrink_fops,
+			shrink_get, shrink_set,
+			"0x%08llx\n");
+
+
 static int msm_gem_show(struct drm_device *dev, struct seq_file *m)
 {
 	struct msm_drm_private *priv = dev->dev_private;
@@ -229,6 +254,9 @@ void msm_debugfs_init(struct drm_minor *minor)
 	debugfs_create_u32("hangcheck_period_ms", 0600, minor->debugfs_root,
 		&priv->hangcheck_period);
 
+	debugfs_create_file("shrink", S_IRWXU, minor->debugfs_root,
+		dev, &shrink_fops);
+
 	if (priv->kms && priv->kms->funcs->debugfs_init)
 		priv->kms->funcs->debugfs_init(priv->kms, minor);
 }

drivers/gpu/drm/msm/msm_drv.h

@@ -299,6 +299,10 @@ bool msm_use_mmu(struct drm_device *dev);
 int msm_ioctl_gem_submit(struct drm_device *dev, void *data,
 		struct drm_file *file);
 
+#ifdef CONFIG_DEBUG_FS
+unsigned long msm_gem_shrinker_shrink(struct drm_device *dev, unsigned long nr_to_scan);
+#endif
+
 void msm_gem_shrinker_init(struct drm_device *dev);
 void msm_gem_shrinker_cleanup(struct drm_device *dev);
 

drivers/gpu/drm/msm/msm_gem_shrinker.c

@@ -145,6 +145,24 @@ msm_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc)
 	return (freed > 0) ? freed : SHRINK_STOP;
 }
 
+#ifdef CONFIG_DEBUG_FS
+unsigned long
+msm_gem_shrinker_shrink(struct drm_device *dev, unsigned long nr_to_scan)
+{
+	struct msm_drm_private *priv = dev->dev_private;
+	struct shrink_control sc = {
+		.nr_to_scan = nr_to_scan,
+	};
+	int ret;
+
+	fs_reclaim_acquire(GFP_KERNEL);
+	ret = msm_gem_shrinker_scan(&priv->shrinker, &sc);
+	fs_reclaim_release(GFP_KERNEL);
+
+	return ret;
+}
+#endif
+
 /* since we don't know any better, lets bail after a few
  * and if necessary the shrinker will be invoked again.
  * Seems better than unmapping *everything*