linux-kernel - [PATCH] media: dibx000_common: Constify struct i2c

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Message-ID: <6539cac4d4eb239e9d2528ae7e34be46fe0e1544.1725780011.git.christophe.jaillet@wanadoo.fr>
Date: Sun,  8 Sep 2024 09:20:37 +0200
From: Christophe JAILLET <christophe.jaillet@...adoo.fr>
To: Mauro Carvalho Chehab <mchehab@...nel.org>
Cc: linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org,
	Christophe JAILLET <christophe.jaillet@...adoo.fr>,
	linux-media@...r.kernel.org
Subject: [PATCH] media: dibx000_common: Constify struct i2c_algorithm

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

To do so, the prototype of i2c_adapter_init() has to be updated as well.

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

On a x86_64, with allmodconfig:
Before:
======
   text	   data	    bss	    dec	    hex	filename
  17213	    932	     20	  18165	   46f5	drivers/media/dvb-frontends/dibx000_common.o

After:
=====
   text	   data	    bss	    dec	    hex	filename
  17490	    660	     20	  18170	   46fa	drivers/media/dvb-frontends/dibx000_common.o

Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
--
Compile tested only
---
 drivers/media/dvb-frontends/dibx000_common.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/media/dvb-frontends/dibx000_common.c b/drivers/media/dvb-frontends/dibx000_common.c
index 63a4c6a4afb5..bd5c5d7223aa 100644
--- a/drivers/media/dvb-frontends/dibx000_common.c
+++ b/drivers/media/dvb-frontends/dibx000_common.c
@@ -250,12 +250,12 @@ static int dibx000_i2c_master_xfer_gpio34(struct i2c_adapter *i2c_adap, struct i
 	return num;
 }
 
-static struct i2c_algorithm dibx000_i2c_master_gpio12_xfer_algo = {
+static const struct i2c_algorithm dibx000_i2c_master_gpio12_xfer_algo = {
 	.master_xfer = dibx000_i2c_master_xfer_gpio12,
 	.functionality = dibx000_i2c_func,
 };
 
-static struct i2c_algorithm dibx000_i2c_master_gpio34_xfer_algo = {
+static const struct i2c_algorithm dibx000_i2c_master_gpio34_xfer_algo = {
 	.master_xfer = dibx000_i2c_master_xfer_gpio34,
 	.functionality = dibx000_i2c_func,
 };
@@ -324,7 +324,7 @@ static int dibx000_i2c_gated_gpio67_xfer(struct i2c_adapter *i2c_adap,
 	return ret;
 }
 
-static struct i2c_algorithm dibx000_i2c_gated_gpio67_algo = {
+static const struct i2c_algorithm dibx000_i2c_gated_gpio67_algo = {
 	.master_xfer = dibx000_i2c_gated_gpio67_xfer,
 	.functionality = dibx000_i2c_func,
 };
@@ -369,7 +369,7 @@ static int dibx000_i2c_gated_tuner_xfer(struct i2c_adapter *i2c_adap,
 	return ret;
 }
 
-static struct i2c_algorithm dibx000_i2c_gated_tuner_algo = {
+static const struct i2c_algorithm dibx000_i2c_gated_tuner_algo = {
 	.master_xfer = dibx000_i2c_gated_tuner_xfer,
 	.functionality = dibx000_i2c_func,
 };
@@ -422,7 +422,7 @@ void dibx000_reset_i2c_master(struct dibx000_i2c_master *mst)
 EXPORT_SYMBOL(dibx000_reset_i2c_master);
 
 static int i2c_adapter_init(struct i2c_adapter *i2c_adap,
-				struct i2c_algorithm *algo, const char *name,
+				const struct i2c_algorithm *algo, const char *name,
 				struct dibx000_i2c_master *mst)
 {
 	strscpy(i2c_adap->name, name, sizeof(i2c_adap->name));
-- 
2.46.0