[PATCH] block/rnbd: Constify struct kobj_type

[PATCH] block/rnbd: Constify struct kobj_type

[Christophe JAILLET]

'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@wanadoo.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

Re: [PATCH] block/rnbd: Constify struct kobj_type

[Chaitanya Kulkarni]

On 7/8/2024 11:11 AM, Christophe JAILLET wrote:
> '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@wanadoo.fr>

Looks good.

Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>

-ck

Re: [PATCH] block/rnbd: Constify struct kobj_type

[Jens Axboe]

On Mon, 08 Jul 2024 20:11:30 +0200, Christophe JAILLET wrote:
> '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
> 
> [...]

Applied, thanks!

[1/1] block/rnbd: Constify struct kobj_type
      commit: e4eaca5e30c55c83c547974188afc2b2d02d4f0c

Best regards,
-- 
Jens Axboe