linux-ext4 - [PATCH 05/29] drm/panfrost: dynamically allocate the drm-panfrost shrinker

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Date:   Thu, 22 Jun 2023 16:53:11 +0800
From:   Qi Zheng <zhengqi.arch@...edance.com>
To:     akpm@...ux-foundation.org, david@...morbit.com, tkhai@...ru,
        vbabka@...e.cz, roman.gushchin@...ux.dev, djwong@...nel.org,
        brauner@...nel.org, paulmck@...nel.org, tytso@....edu
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        intel-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-arm-msm@...r.kernel.org, dm-devel@...hat.com,
        linux-raid@...r.kernel.org, linux-bcache@...r.kernel.org,
        virtualization@...ts.linux-foundation.org,
        linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org,
        linux-nfs@...r.kernel.org, linux-xfs@...r.kernel.org,
        linux-btrfs@...r.kernel.org, Qi Zheng <zhengqi.arch@...edance.com>
Subject: [PATCH 05/29] drm/panfrost: dynamically allocate the drm-panfrost shrinker

In preparation for implementing lockless slab shrink,
we need 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@...edance.com>
---
 drivers/gpu/drm/panfrost/panfrost_device.h    |  2 +-
 .../gpu/drm/panfrost/panfrost_gem_shrinker.c  | 24 ++++++++++---------
 2 files changed, 14 insertions(+), 12 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_gem_shrinker.c b/drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c
index bf0170782f25..2a5513eb9e1f 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;
 
@@ -100,10 +98,15 @@ panfrost_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc)
 void 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_and_init(panfrost_gem_shrinker_count,
+						  panfrost_gem_shrinker_scan, 0,
+						  DEFAULT_SEEKS, 0, pfdev);
+	if (pfdev->shrinker &&
+	    register_shrinker(pfdev->shrinker, "drm-panfrost")) {
+		shrinker_free(pfdev->shrinker);
+		WARN_ON(1);
+	}
 }
 
 /**
@@ -116,7 +119,6 @@ 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->nr_deferred)
+		unregister_and_free_shrinker(pfdev->shrinker);
 }
-- 
2.30.2