linux-kernel - [PATCH] block/rnbd: Constify struct kobj

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Message-ID: <e3d454173ffad30726c9351810d3aa7b75122711.1720462252.git.christophe.jaillet@wanadoo.fr>
Date: Mon,  8 Jul 2024 20:11:30 +0200
From: Christophe JAILLET <christophe.jaillet@...adoo.fr>
To: "Md. Haris Iqbal" <haris.iqbal@...os.com>,
	Jack Wang <jinpu.wang@...os.com>,
	Jens Axboe <axboe@...nel.dk>
Cc: linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org,
	Christophe JAILLET <christophe.jaillet@...adoo.fr>,
	linux-block@...r.kernel.org
Subject: [PATCH] block/rnbd: Constify struct kobj_type

'struct kobj_type' is not modified in this driver. It is only used with
kobject_init_and_add() which takes a "const struct kobj_type *" parameter.

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
   4082	    792	      8	   4882	   1312	drivers/block/rnbd/rnbd-srv-sysfs.o

After:
=====
   text	   data	    bss	    dec	    hex	filename
   4210	    672	      8	   4890	   131a	drivers/block/rnbd/rnbd-srv-sysfs.o

Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
---
Compile tested-only
---
 drivers/block/rnbd/rnbd-clt-sysfs.c | 2 +-
 drivers/block/rnbd/rnbd-srv-sysfs.c | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/block/rnbd/rnbd-clt-sysfs.c b/drivers/block/rnbd/rnbd-clt-sysfs.c
index 39887556cf95..6ea7c12e3a87 100644
--- a/drivers/block/rnbd/rnbd-clt-sysfs.c
+++ b/drivers/block/rnbd/rnbd-clt-sysfs.c
@@ -475,7 +475,7 @@ void rnbd_clt_remove_dev_symlink(struct rnbd_clt_dev *dev)
 	}
 }
 
-static struct kobj_type rnbd_dev_ktype = {
+static const struct kobj_type rnbd_dev_ktype = {
 	.sysfs_ops      = &kobj_sysfs_ops,
 	.default_groups = rnbd_dev_groups,
 };
diff --git a/drivers/block/rnbd/rnbd-srv-sysfs.c b/drivers/block/rnbd/rnbd-srv-sysfs.c
index cba6ba43c2c2..64780094442c 100644
--- a/drivers/block/rnbd/rnbd-srv-sysfs.c
+++ b/drivers/block/rnbd/rnbd-srv-sysfs.c
@@ -33,7 +33,7 @@ static void rnbd_srv_dev_release(struct kobject *kobj)
 	kfree(dev);
 }
 
-static struct kobj_type dev_ktype = {
+static const struct kobj_type dev_ktype = {
 	.sysfs_ops = &kobj_sysfs_ops,
 	.release = rnbd_srv_dev_release
 };
@@ -184,7 +184,7 @@ static void rnbd_srv_sess_dev_release(struct kobject *kobj)
 	rnbd_destroy_sess_dev(sess_dev, sess_dev->keep_id);
 }
 
-static struct kobj_type rnbd_srv_sess_dev_ktype = {
+static const struct kobj_type rnbd_srv_sess_dev_ktype = {
 	.sysfs_ops	= &kobj_sysfs_ops,
 	.release	= rnbd_srv_sess_dev_release,
 };
-- 
2.45.2