[PATCH v4 25/48] drm/panfrost: dynamically allocate the drm-panfrost shrinker

[Qi Zheng via Linux-erofs]

In preparation for implementing lockless slab shrink, use new APIs to
dynamically allocate the drm-panfrost shrinker, so that it can be freed
asynchronously using kfree_rcu(). Then it doesn't need to wait for RCU
read-side critical section when releasing the struct panfrost_device.

Signed-off-by: Qi Zheng <zhengqi.a...@bytedance.com>
Reviewed-by: Steven Price <steven.pr...@arm.com>
---
 drivers/gpu/drm/panfrost/panfrost_device.h    |  2 +-
 drivers/gpu/drm/panfrost/panfrost_drv.c       |  6 +++-
 drivers/gpu/drm/panfrost/panfrost_gem.h       |  2 +-
 .../gpu/drm/panfrost/panfrost_gem_shrinker.c  | 30 +++++++++++--------
 4 files changed, 25 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/panfrost/panfrost_device.h 
b/drivers/gpu/drm/panfrost/panfrost_device.h
index b0126b9fbadc..e667e5689353 100644
--- a/drivers/gpu/drm/panfrost/panfrost_device.h
+++ b/drivers/gpu/drm/panfrost/panfrost_device.h
@@ -118,7 +118,7 @@ struct panfrost_device {
 
        struct mutex shrinker_lock;
        struct list_head shrinker_list;
-       struct shrinker shrinker;
+       struct shrinker *shrinker;
 
        struct panfrost_devfreq pfdevfreq;
 };
diff --git a/drivers/gpu/drm/panfrost/panfrost_drv.c 
b/drivers/gpu/drm/panfrost/panfrost_drv.c
index a2ab99698ca8..e1d0e3a23757 100644
--- a/drivers/gpu/drm/panfrost/panfrost_drv.c
+++ b/drivers/gpu/drm/panfrost/panfrost_drv.c
@@ -601,10 +601,14 @@ static int panfrost_probe(struct platform_device *pdev)
        if (err < 0)
                goto err_out1;
 
-       panfrost_gem_shrinker_init(ddev);
+       err = panfrost_gem_shrinker_init(ddev);
+       if (err)
+               goto err_out2;
 
        return 0;
 
+err_out2:
+       drm_dev_unregister(ddev);
 err_out1:
        pm_runtime_disable(pfdev->dev);
        panfrost_device_fini(pfdev);
diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.h 
b/drivers/gpu/drm/panfrost/panfrost_gem.h
index ad2877eeeccd..863d2ec8d4f0 100644
--- a/drivers/gpu/drm/panfrost/panfrost_gem.h
+++ b/drivers/gpu/drm/panfrost/panfrost_gem.h
@@ -81,7 +81,7 @@ panfrost_gem_mapping_get(struct panfrost_gem_object *bo,
 void panfrost_gem_mapping_put(struct panfrost_gem_mapping *mapping);
 void panfrost_gem_teardown_mappings_locked(struct panfrost_gem_object *bo);
 
-void panfrost_gem_shrinker_init(struct drm_device *dev);
+int panfrost_gem_shrinker_init(struct drm_device *dev);
 void panfrost_gem_shrinker_cleanup(struct drm_device *dev);
 
 #endif /* __PANFROST_GEM_H__ */
diff --git a/drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c 
b/drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c
index 6a71a2555f85..3dfe2b7ccdd9 100644
--- a/drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c
+++ b/drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c
@@ -18,8 +18,7 @@
 static unsigned long
 panfrost_gem_shrinker_count(struct shrinker *shrinker, struct shrink_control 
*sc)
 {
-       struct panfrost_device *pfdev =
-               container_of(shrinker, struct panfrost_device, shrinker);
+       struct panfrost_device *pfdev = shrinker->private_data;
        struct drm_gem_shmem_object *shmem;
        unsigned long count = 0;
 
@@ -65,8 +64,7 @@ static bool panfrost_gem_purge(struct drm_gem_object *obj)
 static unsigned long
 panfrost_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control 
*sc)
 {
-       struct panfrost_device *pfdev =
-               container_of(shrinker, struct panfrost_device, shrinker);
+       struct panfrost_device *pfdev = shrinker->private_data;
        struct drm_gem_shmem_object *shmem, *tmp;
        unsigned long freed = 0;
 
@@ -97,13 +95,22 @@ panfrost_gem_shrinker_scan(struct shrinker *shrinker, 
struct shrink_control *sc)
  *
  * This function registers and sets up the panfrost shrinker.
  */
-void panfrost_gem_shrinker_init(struct drm_device *dev)
+int panfrost_gem_shrinker_init(struct drm_device *dev)
 {
        struct panfrost_device *pfdev = dev->dev_private;
-       pfdev->shrinker.count_objects = panfrost_gem_shrinker_count;
-       pfdev->shrinker.scan_objects = panfrost_gem_shrinker_scan;
-       pfdev->shrinker.seeks = DEFAULT_SEEKS;
-       WARN_ON(register_shrinker(&pfdev->shrinker, "drm-panfrost"));
+
+       pfdev->shrinker = shrinker_alloc(0, "drm-panfrost");
+       if (!pfdev->shrinker)
+               return -ENOMEM;
+
+       pfdev->shrinker->count_objects = panfrost_gem_shrinker_count;
+       pfdev->shrinker->scan_objects = panfrost_gem_shrinker_scan;
+       pfdev->shrinker->seeks = DEFAULT_SEEKS;
+       pfdev->shrinker->private_data = pfdev;
+
+       shrinker_register(pfdev->shrinker);
+
+       return 0;
 }
 
 /**
@@ -116,7 +123,6 @@ void panfrost_gem_shrinker_cleanup(struct drm_device *dev)
 {
        struct panfrost_device *pfdev = dev->dev_private;
 
-       if (pfdev->shrinker.nr_deferred) {
-               unregister_shrinker(&pfdev->shrinker);
-       }
+       if (pfdev->shrinker)
+               shrinker_free(pfdev->shrinker);
 }
-- 
2.30.2