linux-kernel - [PATCH 02/29] mm: vmscan: introduce some helpers for dynamically allocating shrinker

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Message-Id: <20230622083932.4090339-3-qi.zheng@linux.dev>
Date:   Thu, 22 Jun 2023 08:39:05 +0000
From:   Qi Zheng <qi.zheng@...ux.dev>
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,
        freedreno@...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 02/29] mm: vmscan: introduce some helpers for dynamically allocating shrinker

From: Qi Zheng <zhengqi.arch@...edance.com>

Introduce some helpers for dynamically allocating shrinker instance,
and their uses are as follows:

1. shrinker_alloc_and_init()

Used to allocate and initialize a shrinker instance, the priv_data
parameter is used to pass the pointer of the previously embedded
structure of the shrinker instance.

2. shrinker_free()

Used to free the shrinker instance when the registration of shrinker
fails.

3. unregister_and_free_shrinker()

Used to unregister and free the shrinker instance, and the kfree()
will be changed to kfree_rcu() later.

Signed-off-by: Qi Zheng <zhengqi.arch@...edance.com>
---
 include/linux/shrinker.h | 12 ++++++++++++
 mm/vmscan.c              | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 47 insertions(+)

diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h
index 43e6fcabbf51..8e9ba6fa3fcc 100644
--- a/include/linux/shrinker.h
+++ b/include/linux/shrinker.h
@@ -107,6 +107,18 @@ extern void unregister_shrinker(struct shrinker *shrinker);
 extern void free_prealloced_shrinker(struct shrinker *shrinker);
 extern void synchronize_shrinkers(void);
 
+typedef unsigned long (*count_objects_cb)(struct shrinker *s,
+					  struct shrink_control *sc);
+typedef unsigned long (*scan_objects_cb)(struct shrinker *s,
+					 struct shrink_control *sc);
+
+struct shrinker *shrinker_alloc_and_init(count_objects_cb count,
+					 scan_objects_cb scan, long batch,
+					 int seeks, unsigned flags,
+					 void *priv_data);
+void shrinker_free(struct shrinker *shrinker);
+void unregister_and_free_shrinker(struct shrinker *shrinker);
+
 #ifdef CONFIG_SHRINKER_DEBUG
 extern int shrinker_debugfs_add(struct shrinker *shrinker);
 extern struct dentry *shrinker_debugfs_detach(struct shrinker *shrinker,
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 45d17c7cc555..64ff598fbad9 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -809,6 +809,41 @@ void unregister_shrinker(struct shrinker *shrinker)
 }
 EXPORT_SYMBOL(unregister_shrinker);
 
+struct shrinker *shrinker_alloc_and_init(count_objects_cb count,
+					 scan_objects_cb scan, long batch,
+					 int seeks, unsigned flags,
+					 void *priv_data)
+{
+	struct shrinker *shrinker;
+
+	shrinker = kzalloc(sizeof(struct shrinker), GFP_KERNEL);
+	if (!shrinker)
+		return NULL;
+
+	shrinker->count_objects = count;
+	shrinker->scan_objects = scan;
+	shrinker->batch = batch;
+	shrinker->seeks = seeks;
+	shrinker->flags = flags;
+	shrinker->private_data = priv_data;
+
+	return shrinker;
+}
+EXPORT_SYMBOL(shrinker_alloc_and_init);
+
+void shrinker_free(struct shrinker *shrinker)
+{
+	kfree(shrinker);
+}
+EXPORT_SYMBOL(shrinker_free);
+
+void unregister_and_free_shrinker(struct shrinker *shrinker)
+{
+	unregister_shrinker(shrinker);
+	kfree(shrinker);
+}
+EXPORT_SYMBOL(unregister_and_free_shrinker);
+
 /**
  * synchronize_shrinkers - Wait for all running shrinkers to complete.
  *
-- 
2.30.2