mm/sl[au]b: Move print_slabinfo_header to slab_common.c

The header format is highly similar between slab and slub. The main
difference lays in the fact that slab may optionally have statistics
added here in case of CONFIG_SLAB_DEBUG, while the slub will stick them
somewhere else.

By making sure that information conditionally lives inside a
globally-visible CONFIG_DEBUG_SLAB switch, we can move the header
printing to a common location.

Signed-off-by: Glauber Costa <glommer@parallels.com>
Acked-by: Christoph Lameter <cl@linux.com>
CC: David Rientjes <rientjes@google.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>

mm/slab.c

diff --git a/mm/slab.c b/mm/slab.c
index a6e045c..73811ca 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -4276,30 +4276,6 @@
 }
 
 #ifdef CONFIG_SLABINFO
-
-void print_slabinfo_header(struct seq_file *m)
-{
-	/*
-	 * Output format version, so at least we can change it
-	 * without _too_ many complaints.
-	 */
-#if STATS
-	seq_puts(m, "slabinfo - version: 2.1 (statistics)\n");
-#else
-	seq_puts(m, "slabinfo - version: 2.1\n");
-#endif
-	seq_puts(m, "# name            <active_objs> <num_objs> <objsize> "
-		 "<objperslab> <pagesperslab>");
-	seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>");
-	seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>");
-#if STATS
-	seq_puts(m, " : globalstat <listallocs> <maxobjs> <grown> <reaped> "
-		 "<error> <maxfreeable> <nodeallocs> <remotefrees> <alienoverflow>");
-	seq_puts(m, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>");
-#endif
-	seq_putc(m, '\n');
-}
-
 int slabinfo_show(struct seq_file *m, void *p)
 {
 	struct kmem_cache *cachep = list_entry(p, struct kmem_cache, list);

mm/slab.h

diff --git a/mm/slab.h b/mm/slab.h
index dc78101..3442eb8 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -49,8 +49,6 @@
 
 struct seq_file;
 struct file;
-void print_slabinfo_header(struct seq_file *m);
-
 int slabinfo_show(struct seq_file *m, void *p);
 
 ssize_t slabinfo_write(struct file *file, const char __user *buffer,

mm/slab_common.c

diff --git a/mm/slab_common.c b/mm/slab_common.c
index 2e4b4c6..c64a043 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -196,6 +196,29 @@
 }
 
 #ifdef CONFIG_SLABINFO
+static void print_slabinfo_header(struct seq_file *m)
+{
+	/*
+	 * Output format version, so at least we can change it
+	 * without _too_ many complaints.
+	 */
+#ifdef CONFIG_DEBUG_SLAB
+	seq_puts(m, "slabinfo - version: 2.1 (statistics)\n");
+#else
+	seq_puts(m, "slabinfo - version: 2.1\n");
+#endif
+	seq_puts(m, "# name            <active_objs> <num_objs> <objsize> "
+		 "<objperslab> <pagesperslab>");
+	seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>");
+	seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>");
+#ifdef CONFIG_DEBUG_SLAB
+	seq_puts(m, " : globalstat <listallocs> <maxobjs> <grown> <reaped> "
+		 "<error> <maxfreeable> <nodeallocs> <remotefrees> <alienoverflow>");
+	seq_puts(m, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>");
+#endif
+	seq_putc(m, '\n');
+}
+
 static void *s_start(struct seq_file *m, loff_t *pos)
 {
 	loff_t n = *pos;

mm/slub.c

diff --git a/mm/slub.c b/mm/slub.c
index 77a0c8a..6b5ee34 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -5405,16 +5405,6 @@
  * The /proc/slabinfo ABI
  */
 #ifdef CONFIG_SLABINFO
-void print_slabinfo_header(struct seq_file *m)
-{
-	seq_puts(m, "slabinfo - version: 2.1\n");
-	seq_puts(m, "# name            <active_objs> <num_objs> <object_size> "
-		 "<objperslab> <pagesperslab>");
-	seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>");
-	seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>");
-	seq_putc(m, '\n');
-}
-
 int slabinfo_show(struct seq_file *m, void *p)
 {
 	unsigned long nr_partials = 0;