md-cluster: Constify struct md_cluster_operations

Commit Message

Christophe JAILLET June 23, 2024, 8:17 p.m. UTC

'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 <[e-mail]>
---
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(-)

Comments

Song Liu July 4, 2024, 7:07 a.m. UTC | #1

On Mon, Jun 24, 2024 at 4:18 AM Christophe JAILLET
<[e-mail]> wrote:
>
> '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 <[e-mail]>

Applied to md-6.11. Thanks!

Song

Patch

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;