mm: slab: make slab iterator functions static

There is no external users of slab_start/next/stop(), so make them
static.  And the memory.kmem.slabinfo is deprecated, which outputs
nothing now, so move memcg_slab_show() into mm/memcontrol.c and rename
it to mem_cgroup_slab_show to be consistent with other function names.

Link: https://lkml.kernel.org/r/20211109133359.32881-1-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/memcontrol.c

@@ -4845,6 +4845,17 @@ static ssize_t memcg_write_event_control(struct kernfs_open_file *of,
 	return ret;
 }
 
+#if defined(CONFIG_MEMCG_KMEM) && (defined(CONFIG_SLAB) || defined(CONFIG_SLUB_DEBUG))
+static int mem_cgroup_slab_show(struct seq_file *m, void *p)
+{
+	/*
+	 * Deprecated.
+	 * Please, take a look at tools/cgroup/slabinfo.py .
+	 */
+	return 0;
+}
+#endif
+
 static struct cftype mem_cgroup_legacy_files[] = {
 	{
 		.name = "usage_in_bytes",
@@ -4945,7 +4956,7 @@ static struct cftype mem_cgroup_legacy_files[] = {
 	(defined(CONFIG_SLAB) || defined(CONFIG_SLUB_DEBUG))
 	{
 		.name = "kmem.slabinfo",
-		.seq_show = memcg_slab_show,
+		.seq_show = mem_cgroup_slab_show,
 	},
 #endif
 	{

mm/slab.h

@@ -575,11 +575,6 @@ static inline struct kmem_cache_node *get_node(struct kmem_cache *s, int node)
 
 #endif
 
-void *slab_start(struct seq_file *m, loff_t *pos);
-void *slab_next(struct seq_file *m, void *p, loff_t *pos);
-void slab_stop(struct seq_file *m, void *p);
-int memcg_slab_show(struct seq_file *m, void *p);
-
 #if defined(CONFIG_SLAB) || defined(CONFIG_SLUB_DEBUG)
 void dump_unreclaimable_slab(void);
 #else

mm/slab_common.c

@@ -1039,18 +1039,18 @@ static void print_slabinfo_header(struct seq_file *m)
 	seq_putc(m, '\n');
 }
 
-void *slab_start(struct seq_file *m, loff_t *pos)
+static void *slab_start(struct seq_file *m, loff_t *pos)
 {
 	mutex_lock(&slab_mutex);
 	return seq_list_start(&slab_caches, *pos);
 }
 
-void *slab_next(struct seq_file *m, void *p, loff_t *pos)
+static void *slab_next(struct seq_file *m, void *p, loff_t *pos)
 {
 	return seq_list_next(p, &slab_caches, pos);
 }
 
-void slab_stop(struct seq_file *m, void *p)
+static void slab_stop(struct seq_file *m, void *p)
 {
 	mutex_unlock(&slab_mutex);
 }
@@ -1118,17 +1118,6 @@ void dump_unreclaimable_slab(void)
 	mutex_unlock(&slab_mutex);
 }
 
-#if defined(CONFIG_MEMCG_KMEM)
-int memcg_slab_show(struct seq_file *m, void *p)
-{
-	/*
-	 * Deprecated.
-	 * Please, take a look at tools/cgroup/slabinfo.py .
-	 */
-	return 0;
-}
-#endif
-
 /*
  * slabinfo_op - iterator that generates /proc/slabinfo
  *