In preparation for implementing lockless slab shrink, use new APIs to
dynamically allocate the i915_gem_mm 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 drm_i915_private.

Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
---
 drivers/gpu/drm/i915/gem/i915_gem_shrinker.c | 30 +++++++++++---------
 drivers/gpu/drm/i915/i915_drv.h              |  2 +-
 2 files changed, 18 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shrinker.c b/drivers/gpu/drm/i915/gem/i915_gem_shrinker.c
index 214763942aa2..4504eb4f31d5 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_shrinker.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_shrinker.c
@@ -284,8 +284,7 @@ unsigned long i915_gem_shrink_all(struct drm_i915_private *i915)
 static unsigned long
 i915_gem_shrinker_count(struct shrinker *shrinker, struct shrink_control *sc)
 {
-	struct drm_i915_private *i915 =
-		container_of(shrinker, struct drm_i915_private, mm.shrinker);
+	struct drm_i915_private *i915 = shrinker->private_data;
 	unsigned long num_objects;
 	unsigned long count;
 
@@ -302,8 +301,8 @@ i915_gem_shrinker_count(struct shrinker *shrinker, struct shrink_control *sc)
 	if (num_objects) {
 		unsigned long avg = 2 * count / num_objects;
 
-		i915->mm.shrinker.batch =
-			max((i915->mm.shrinker.batch + avg) >> 1,
+		i915->mm.shrinker->batch =
+			max((i915->mm.shrinker->batch + avg) >> 1,
 			    128ul /* default SHRINK_BATCH */);
 	}
 
@@ -313,8 +312,7 @@ i915_gem_shrinker_count(struct shrinker *shrinker, struct shrink_control *sc)
 static unsigned long
 i915_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc)
 {
-	struct drm_i915_private *i915 =
-		container_of(shrinker, struct drm_i915_private, mm.shrinker);
+	struct drm_i915_private *i915 = shrinker->private_data;
 	unsigned long freed;
 
 	sc->nr_scanned = 0;
@@ -422,12 +420,18 @@ i915_gem_shrinker_vmap(struct notifier_block *nb, unsigned long event, void *ptr
 
 void i915_gem_driver_register__shrinker(struct drm_i915_private *i915)
 {
-	i915->mm.shrinker.scan_objects = i915_gem_shrinker_scan;
-	i915->mm.shrinker.count_objects = i915_gem_shrinker_count;
-	i915->mm.shrinker.seeks = DEFAULT_SEEKS;
-	i915->mm.shrinker.batch = 4096;
-	drm_WARN_ON(&i915->drm, register_shrinker(&i915->mm.shrinker,
-						  "drm-i915_gem"));
+	i915->mm.shrinker = shrinker_alloc(0, "drm-i915_gem");
+	if (!i915->mm.shrinker) {
+		drm_WARN_ON(&i915->drm, 1);
+	} else {
+		i915->mm.shrinker->scan_objects = i915_gem_shrinker_scan;
+		i915->mm.shrinker->count_objects = i915_gem_shrinker_count;
+		i915->mm.shrinker->seeks = DEFAULT_SEEKS;
+		i915->mm.shrinker->batch = 4096;
+		i915->mm.shrinker->private_data = i915;
+
+		shrinker_register(i915->mm.shrinker);
+	}
 
 	i915->mm.oom_notifier.notifier_call = i915_gem_shrinker_oom;
 	drm_WARN_ON(&i915->drm, register_oom_notifier(&i915->mm.oom_notifier));
@@ -443,7 +447,7 @@ void i915_gem_driver_unregister__shrinker(struct drm_i915_private *i915)
 		    unregister_vmap_purge_notifier(&i915->mm.vmap_notifier));
 	drm_WARN_ON(&i915->drm,
 		    unregister_oom_notifier(&i915->mm.oom_notifier));
-	unregister_shrinker(&i915->mm.shrinker);
+	shrinker_free(i915->mm.shrinker);
 }
 
 void i915_gem_shrinker_taints_mutex(struct drm_i915_private *i915,
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 682ef2b5c7d5..389e8bf140d7 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -163,7 +163,7 @@ struct i915_gem_mm {
 
 	struct notifier_block oom_notifier;
 	struct notifier_block vmap_notifier;
-	struct shrinker shrinker;
+	struct shrinker *shrinker;
 
 #ifdef CONFIG_MMU_NOTIFIER
 	/**
-- 
2.30.2