linux-kernel - [PATCH] i2c: virtio: Constify struct i2c_algorithm and struct virtio_device

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Message-ID: <b98c3fa7072bf519ce8a9bc771e9d18c091b3509.1725778305.git.christophe.jaillet@wanadoo.fr>
Date: Sun,  8 Sep 2024 08:52:07 +0200
From: Christophe JAILLET <christophe.jaillet@...adoo.fr>
To: Viresh Kumar <viresh.kumar@...aro.org>,
	"Chen, Jian Jun" <jian.jun.chen@...el.com>,
	Andi Shyti <andi.shyti@...nel.org>
Cc: linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org,
	Christophe JAILLET <christophe.jaillet@...adoo.fr>,
	linux-i2c@...r.kernel.org,
	virtualization@...ts.linux.dev
Subject: [PATCH] i2c: virtio: Constify struct i2c_algorithm and struct virtio_device_id

'struct i2c_algorithm' and 'struct virtio_device_id' are not modified in
this driver.

Constifying this structure moves some data to a read-only section, so
increase overall security, especially when the structure holds some
function pointers, which is the case for struct i2c_algorithm.

On a x86_64, with allmodconfig:
Before:
======
   text	   data	    bss	    dec	    hex	filename
   6663	    568	     16	   7247	   1c4f	drivers/i2c/busses/i2c-virtio.o

After:
=====
   text	   data	    bss	    dec	    hex	filename
   6735	    472	     16	   7223	   1c37	drivers/i2c/busses/i2c-virtio.o

Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
--
Compile tested only
---
 drivers/i2c/busses/i2c-virtio.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-virtio.c b/drivers/i2c/busses/i2c-virtio.c
index 52ba1e0845ca..2a351f961b89 100644
--- a/drivers/i2c/busses/i2c-virtio.c
+++ b/drivers/i2c/busses/i2c-virtio.c
@@ -182,7 +182,7 @@ static u32 virtio_i2c_func(struct i2c_adapter *adap)
 	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 }
 
-static struct i2c_algorithm virtio_algorithm = {
+static const struct i2c_algorithm virtio_algorithm = {
 	.xfer = virtio_i2c_xfer,
 	.functionality = virtio_i2c_func,
 };
@@ -237,7 +237,7 @@ static void virtio_i2c_remove(struct virtio_device *vdev)
 	virtio_i2c_del_vqs(vdev);
 }
 
-static struct virtio_device_id id_table[] = {
+static const struct virtio_device_id id_table[] = {
 	{ VIRTIO_ID_I2C_ADAPTER, VIRTIO_DEV_ANY_ID },
 	{}
 };
-- 
2.46.0