linux-kernel - [PATCH] md-cluster: Constify struct md_cluster

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Date: Sun, 23 Jun 2024 22:17:54 +0200
From: Christophe JAILLET <christophe.jaillet@...adoo.fr>
To: Song Liu <song@...nel.org>,
	Yu Kuai <yukuai3@...wei.com>
Cc: linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org,
	Christophe JAILLET <christophe.jaillet@...adoo.fr>,
	linux-raid@...r.kernel.org
Subject: [PATCH] md-cluster: Constify struct md_cluster_operations

'struct md_cluster_operations' is not modified in this driver.

Constifying this structure moves some data to a read-only section, so
increase overall security.

On a x86_64, with allmodconfig, as an example:
Before:
======
   text	   data	    bss	    dec	    hex	filename
  51941	   1442	     80	  53463	   d0d7	drivers/md/md-cluster.o

After:
=====
   text	   data	    bss	    dec	    hex	filename
  52133	   1246	     80	  53459	   d0d3	drivers/md/md-cluster.o

Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
---
Compile tested-only
---
 drivers/md/md-cluster.c | 2 +-
 drivers/md/md.c         | 4 ++--
 drivers/md/md.h         | 4 ++--
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/md/md-cluster.c b/drivers/md/md-cluster.c
index eb9bbf12c8d8..c1ea214bfc91 100644
--- a/drivers/md/md-cluster.c
+++ b/drivers/md/md-cluster.c
@@ -1570,7 +1570,7 @@ static int gather_bitmaps(struct md_rdev *rdev)
 	return err;
 }
 
-static struct md_cluster_operations cluster_ops = {
+static const struct md_cluster_operations cluster_ops = {
 	.join   = join,
 	.leave  = leave,
 	.slot_number = slot_number,
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 69ea54aedd99..8221c9b641ab 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -85,7 +85,7 @@ static DEFINE_SPINLOCK(pers_lock);
 
 static const struct kobj_type md_ktype;
 
-struct md_cluster_operations *md_cluster_ops;
+const struct md_cluster_operations *md_cluster_ops;
 EXPORT_SYMBOL(md_cluster_ops);
 static struct module *md_cluster_mod;
 
@@ -8539,7 +8539,7 @@ int unregister_md_personality(struct md_personality *p)
 }
 EXPORT_SYMBOL(unregister_md_personality);
 
-int register_md_cluster_operations(struct md_cluster_operations *ops,
+int register_md_cluster_operations(const struct md_cluster_operations *ops,
 				   struct module *module)
 {
 	int ret = 0;
diff --git a/drivers/md/md.h b/drivers/md/md.h
index c4d7ebf9587d..e394e5bd39fc 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -849,7 +849,7 @@ static inline void safe_put_page(struct page *p)
 
 extern int register_md_personality(struct md_personality *p);
 extern int unregister_md_personality(struct md_personality *p);
-extern int register_md_cluster_operations(struct md_cluster_operations *ops,
+extern int register_md_cluster_operations(const struct md_cluster_operations *ops,
 		struct module *module);
 extern int unregister_md_cluster_operations(void);
 extern int md_setup_cluster(struct mddev *mddev, int nodes);
@@ -931,7 +931,7 @@ static inline void rdev_dec_pending(struct md_rdev *rdev, struct mddev *mddev)
 	}
 }
 
-extern struct md_cluster_operations *md_cluster_ops;
+extern const struct md_cluster_operations *md_cluster_ops;
 static inline int mddev_is_clustered(struct mddev *mddev)
 {
 	return mddev->cluster_info && mddev->bitmap_info.nodes > 1;
-- 
2.45.2