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

Qi Zheng
2023-08-07T11:27:39Z

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.arch@bytedance.com>
Reviewed-by: Steven Price <steven.price@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