linux-kernel - [PATCH] kernel/ksysfs.c: simplify bin

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Message-Id: <20241121-sysfs-const-bin_attr-ksysfs-v1-1-972faced149d@weissschuh.net>
Date: Thu, 21 Nov 2024 17:48:47 +0100
From: Thomas Weißschuh <linux@...ssschuh.net>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
 Thomas Weißschuh <linux@...ssschuh.net>
Subject: [PATCH] kernel/ksysfs.c: simplify bin_attribute definition

The notes attribute can be implemented in terms of BIN_ATTR_SIMPLE().
This saves memory at runtime and is a preparation for the constification
of struct bin_attribute.

Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Thomas Weißschuh <linux@...ssschuh.net>
---
 kernel/ksysfs.c | 21 ++++-----------------
 1 file changed, 4 insertions(+), 17 deletions(-)

diff --git a/kernel/ksysfs.c b/kernel/ksysfs.c
index 1bab21b4718fffd9fa1c76d46827f44af870dd9d..eefb67d9883c2ca876023d75bb752b26a93a839b 100644
--- a/kernel/ksysfs.c
+++ b/kernel/ksysfs.c
@@ -239,21 +239,7 @@ extern const void __start_notes;
 extern const void __stop_notes;
 #define	notes_size (&__stop_notes - &__start_notes)
 
-static ssize_t notes_read(struct file *filp, struct kobject *kobj,
-			  struct bin_attribute *bin_attr,
-			  char *buf, loff_t off, size_t count)
-{
-	memcpy(buf, &__start_notes + off, count);
-	return count;
-}
-
-static struct bin_attribute notes_attr __ro_after_init  = {
-	.attr = {
-		.name = "notes",
-		.mode = S_IRUGO,
-	},
-	.read = &notes_read,
-};
+static __ro_after_init BIN_ATTR_SIMPLE_RO(notes);
 
 struct kobject *kernel_kobj;
 EXPORT_SYMBOL_GPL(kernel_kobj);
@@ -307,8 +293,9 @@ static int __init ksysfs_init(void)
 		goto kset_exit;
 
 	if (notes_size > 0) {
-		notes_attr.size = notes_size;
-		error = sysfs_create_bin_file(kernel_kobj, &notes_attr);
+		bin_attr_notes.private = (void *)&__start_notes;
+		bin_attr_notes.size = notes_size;
+		error = sysfs_create_bin_file(kernel_kobj, &bin_attr_notes);
 		if (error)
 			goto group_exit;
 	}

---
base-commit: 43fb83c17ba2d63dfb798f0be7453ed55ca3f9c2
change-id: 20241121-sysfs-const-bin_attr-ksysfs-cda4708a6a02

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