linux-kernel - [PATCH] mm/page_idle: Constify 'struct bin

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Message-Id: <20241216-sysfs-const-bin_attr-page_idle-v1-1-cc01ecc55196@weissschuh.net>
Date: Mon, 16 Dec 2024 13:20:25 +0100
From: Thomas Weißschuh <linux@...ssschuh.net>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org, 
 Thomas Weißschuh <linux@...ssschuh.net>
Subject: [PATCH] mm/page_idle: Constify 'struct bin_attribute'

The sysfs core now allows instances of 'struct bin_attribute' to be
moved into read-only memory. Make use of that to protect them against
accidental or malicious modifications.

Signed-off-by: Thomas Weißschuh <linux@...ssschuh.net>
---
 mm/page_idle.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/mm/page_idle.c b/mm/page_idle.c
index 41ea77f22011ebc88cd0fe1e40abad6d11ff9b08..947c7c7a37289ad386f140047f733d4388833546 100644
--- a/mm/page_idle.c
+++ b/mm/page_idle.c
@@ -112,7 +112,7 @@ static void page_idle_clear_pte_refs(struct folio *folio)
 }
 
 static ssize_t page_idle_bitmap_read(struct file *file, struct kobject *kobj,
-				     struct bin_attribute *attr, char *buf,
+				     const struct bin_attribute *attr, char *buf,
 				     loff_t pos, size_t count)
 {
 	u64 *out = (u64 *)buf;
@@ -157,7 +157,7 @@ static ssize_t page_idle_bitmap_read(struct file *file, struct kobject *kobj,
 }
 
 static ssize_t page_idle_bitmap_write(struct file *file, struct kobject *kobj,
-				      struct bin_attribute *attr, char *buf,
+				      const struct bin_attribute *attr, char *buf,
 				      loff_t pos, size_t count)
 {
 	const u64 *in = (u64 *)buf;
@@ -193,17 +193,17 @@ static ssize_t page_idle_bitmap_write(struct file *file, struct kobject *kobj,
 	return (char *)in - buf;
 }
 
-static struct bin_attribute page_idle_bitmap_attr =
+static const struct bin_attribute page_idle_bitmap_attr =
 		__BIN_ATTR(bitmap, 0600,
 			   page_idle_bitmap_read, page_idle_bitmap_write, 0);
 
-static struct bin_attribute *page_idle_bin_attrs[] = {
+static const struct bin_attribute *const page_idle_bin_attrs[] = {
 	&page_idle_bitmap_attr,
 	NULL,
 };
 
 static const struct attribute_group page_idle_attr_group = {
-	.bin_attrs = page_idle_bin_attrs,
+	.bin_attrs_new = page_idle_bin_attrs,
 	.name = "page_idle",
 };
 

---
base-commit: 78d4f34e2115b517bcbfe7ec0d018bbbb6f9b0b8
change-id: 20241216-sysfs-const-bin_attr-page_idle-5eab6e9e70ff

Best regards,
-- 
Thomas Weißschuh <linux@...ssschuh.net>