[PATCH] mm: shrinker: some cleanup

[Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>]

Signed-off-by: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
Reviewed-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
---
Hi Andrew, this is a cleanup patch for [PATCH v6 01/45], there will be a
small conflict with [PATCH v6 41/45].

 include/linux/shrinker.h | 14 ++++++++------
 mm/internal.h            | 17 ++++++++++++++---
 mm/shrinker.c            | 20 ++++++++++++--------
 mm/shrinker_debug.c      | 16 ----------------
 4 files changed, 34 insertions(+), 33 deletions(-)

diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h
index 3f3fd9974ce5..f4a5249f00b2 100644
--- a/include/linux/shrinker.h
+++ b/include/linux/shrinker.h
@@ -88,16 +88,18 @@ struct shrinker {
 };
 #define DEFAULT_SEEKS 2 /* A good number if you don't know better. */
 
-/* Flags */
-#define SHRINKER_REGISTERED	(1 << 0)
-#define SHRINKER_NUMA_AWARE	(1 << 1)
-#define SHRINKER_MEMCG_AWARE	(1 << 2)
+/* Internal flags */
+#define SHRINKER_REGISTERED	BIT(0)
+#define SHRINKER_ALLOCATED	BIT(1)
+
+/* Flags for users to use */
+#define SHRINKER_NUMA_AWARE	BIT(2)
+#define SHRINKER_MEMCG_AWARE	BIT(3)
 /*
  * It just makes sense when the shrinker is also MEMCG_AWARE for now,
  * non-MEMCG_AWARE shrinker should not have this flag set.
  */
-#define SHRINKER_NONSLAB	(1 << 3)
-#define SHRINKER_ALLOCATED	(1 << 4)
+#define SHRINKER_NONSLAB	BIT(4)
 
 struct shrinker *shrinker_alloc(unsigned int flags, const char *fmt, ...);
 void shrinker_register(struct shrinker *shrinker);
diff --git a/mm/internal.h b/mm/internal.h
index b9a116dce28e..0f418a11c7a8 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -1161,10 +1161,21 @@ unsigned long shrink_slab(gfp_t gfp_mask, int nid, struct mem_cgroup *memcg,
 			  int priority);
 
 #ifdef CONFIG_SHRINKER_DEBUG
+static inline int shrinker_debugfs_name_alloc(struct shrinker *shrinker,
+					      const char *fmt, va_list ap)
+{
+	shrinker->name = kvasprintf_const(GFP_KERNEL, fmt, ap);
+
+	return shrinker->name ? 0 : -ENOMEM;
+}
+
+static inline void shrinker_debugfs_name_free(struct shrinker *shrinker)
+{
+	kfree_const(shrinker->name);
+	shrinker->name = NULL;
+}
+
 extern int shrinker_debugfs_add(struct shrinker *shrinker);
-extern int shrinker_debugfs_name_alloc(struct shrinker *shrinker,
-				       const char *fmt, va_list ap);
-extern void shrinker_debugfs_name_free(struct shrinker *shrinker);
 extern struct dentry *shrinker_debugfs_detach(struct shrinker *shrinker,
 					      int *debugfs_id);
 extern void shrinker_debugfs_remove(struct dentry *debugfs_entry,
diff --git a/mm/shrinker.c b/mm/shrinker.c
index 201211a67827..d1032a4d5684 100644
--- a/mm/shrinker.c
+++ b/mm/shrinker.c
@@ -572,18 +572,23 @@ struct shrinker *shrinker_alloc(unsigned int flags, const char *fmt, ...)
 
 	if (flags & SHRINKER_MEMCG_AWARE) {
 		err = prealloc_memcg_shrinker(shrinker);
-		if (err == -ENOSYS)
+		if (err == -ENOSYS) {
+			/* Memcg is not supported, fallback to non-memcg-aware shrinker. */
 			shrinker->flags &= ~SHRINKER_MEMCG_AWARE;
-		else if (err == 0)
-			goto done;
-		else
+			goto non_memcg;
+		}
+
+		if (err)
 			goto err_flags;
+
+		return shrinker;
 	}
 
+non_memcg:
 	/*
 	 * The nr_deferred is available on per memcg level for memcg aware
 	 * shrinkers, so only allocate nr_deferred in the following cases:
-	 *  - non memcg aware shrinkers
+	 *  - non-memcg-aware shrinkers
 	 *  - !CONFIG_MEMCG
 	 *  - memcg is disabled by kernel command line
 	 */
@@ -595,7 +600,6 @@ struct shrinker *shrinker_alloc(unsigned int flags, const char *fmt, ...)
 	if (!shrinker->nr_deferred)
 		goto err_flags;
 
-done:
 	return shrinker;
 
 err_flags:
@@ -634,10 +638,10 @@ void shrinker_free(struct shrinker *shrinker)
 		list_del(&shrinker->list);
 		debugfs_entry = shrinker_debugfs_detach(shrinker, &debugfs_id);
 		shrinker->flags &= ~SHRINKER_REGISTERED;
-	} else {
-		shrinker_debugfs_name_free(shrinker);
 	}
 
+	shrinker_debugfs_name_free(shrinker);
+
 	if (shrinker->flags & SHRINKER_MEMCG_AWARE)
 		unregister_memcg_shrinker(shrinker);
 	up_write(&shrinker_rwsem);
diff --git a/mm/shrinker_debug.c b/mm/shrinker_debug.c
index 38452f539f40..24aebe7c24cc 100644
--- a/mm/shrinker_debug.c
+++ b/mm/shrinker_debug.c
@@ -193,20 +193,6 @@ int shrinker_debugfs_add(struct shrinker *shrinker)
 	return 0;
 }
 
-int shrinker_debugfs_name_alloc(struct shrinker *shrinker, const char *fmt,
-				va_list ap)
-{
-	shrinker->name = kvasprintf_const(GFP_KERNEL, fmt, ap);
-
-	return shrinker->name ? 0 : -ENOMEM;
-}
-
-void shrinker_debugfs_name_free(struct shrinker *shrinker)
-{
-	kfree_const(shrinker->name);
-	shrinker->name = NULL;
-}
-
 int shrinker_debugfs_rename(struct shrinker *shrinker, const char *fmt, ...)
 {
 	struct dentry *entry;
@@ -255,8 +241,6 @@ struct dentry *shrinker_debugfs_detach(struct shrinker *shrinker,
 
 	lockdep_assert_held(&shrinker_rwsem);
 
-	shrinker_debugfs_name_free(shrinker);
-
 	*debugfs_id = entry ? shrinker->debugfs_id : -1;
 	shrinker->debugfs_entry = NULL;
 
-- 
2.30.2