[PATCH] md-cluster: Constify struct md_cluster_operations

From: Christophe JAILLET
Date: Sun Jun 23 2024 - 16:18:16 EST


'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@xxxxxxxxxx>
---
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