linux-kernel - [PATCH 1/3] params: Prepare for 'const struct module

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Message-Id: <20241216-sysfs-const-attr-module-v1-1-3790b53e0abf@weissschuh.net>
Date: Mon, 16 Dec 2024 18:25:08 +0100
From: Thomas Weißschuh <linux@...ssschuh.net>
To: Luis Chamberlain <mcgrof@...nel.org>, Petr Pavlu <petr.pavlu@...e.com>, 
 Sami Tolvanen <samitolvanen@...gle.com>, 
 Daniel Gomez <da.gomez@...sung.com>
Cc: linux-modules@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Thomas Weißschuh <linux@...ssschuh.net>
Subject: [PATCH 1/3] params: Prepare for 'const struct module_attribute *'

The 'struct module_attribute' sysfs callbacks are about to change to
receive a 'const struct module_attribute *' parameter.
Prepare for that by avoid casting away the constness through
container_of() and using const pointers to 'struct param_attribute'.

Signed-off-by: Thomas Weißschuh <linux@...ssschuh.net>
---
 kernel/params.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/params.c b/kernel/params.c
index 2e447f8ae183e7ec6d1815c862e0cec6572099d4..e90733824528eacc77046f85c9ab4243467ca841 100644
--- a/kernel/params.c
+++ b/kernel/params.c
@@ -555,13 +555,13 @@ struct module_param_attrs
 };
 
 #ifdef CONFIG_SYSFS
-#define to_param_attr(n) container_of(n, struct param_attribute, mattr)
+#define to_param_attr(n) container_of_const(n, struct param_attribute, mattr)
 
 static ssize_t param_attr_show(struct module_attribute *mattr,
 			       struct module_kobject *mk, char *buf)
 {
 	int count;
-	struct param_attribute *attribute = to_param_attr(mattr);
+	const struct param_attribute *attribute = to_param_attr(mattr);
 
 	if (!attribute->param->ops->get)
 		return -EPERM;
@@ -578,7 +578,7 @@ static ssize_t param_attr_store(struct module_attribute *mattr,
 				const char *buf, size_t len)
 {
  	int err;
-	struct param_attribute *attribute = to_param_attr(mattr);
+	const struct param_attribute *attribute = to_param_attr(mattr);
 
 	if (!attribute->param->ops->set)
 		return -EPERM;

-- 
2.47.1