sysfs: constify bin_attribute argument of bin_attribute::read/write()

All callback implementers have been moved to the const variant of the
callbacks. The signature of the original callbacks can now be changed.
Also remove the now unnecessary transition machinery inside __BIN_ATTR().

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Link: https://lore.kernel.org/r/20250313-sysfs-const-bin_attr-final-v2-1-96284e1e88ce@weissschuh.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: t-8ch

include/linux/sysfs.h

@@ -306,11 +306,11 @@ struct bin_attribute {
 	size_t			size;
 	void			*private;
 	struct address_space *(*f_mapping)(void);
-	ssize_t (*read)(struct file *, struct kobject *, struct bin_attribute *,
+	ssize_t (*read)(struct file *, struct kobject *, const struct bin_attribute *,
 			char *, loff_t, size_t);
 	ssize_t (*read_new)(struct file *, struct kobject *, const struct bin_attribute *,
 			    char *, loff_t, size_t);
-	ssize_t (*write)(struct file *, struct kobject *, struct bin_attribute *,
+	ssize_t (*write)(struct file *, struct kobject *, const struct bin_attribute *,
 			 char *, loff_t, size_t);
 	ssize_t (*write_new)(struct file *, struct kobject *,
 			     const struct bin_attribute *, char *, loff_t, size_t);
@@ -332,28 +332,11 @@ struct bin_attribute {
  */
 #define sysfs_bin_attr_init(bin_attr) sysfs_attr_init(&(bin_attr)->attr)
 
-typedef ssize_t __sysfs_bin_rw_handler_new(struct file *, struct kobject *,
-					   const struct bin_attribute *, char *, loff_t, size_t);
-
 /* macros to create static binary attributes easier */
 #define __BIN_ATTR(_name, _mode, _read, _write, _size) {		\
 	.attr = { .name = __stringify(_name), .mode = _mode },		\
-	.read = _Generic(_read,						\
-		__sysfs_bin_rw_handler_new * : NULL,			\
-		default : _read						\
-	),								\
-	.read_new = _Generic(_read,					\
-		__sysfs_bin_rw_handler_new * : _read,			\
-		default : NULL						\
-	),								\
-	.write = _Generic(_write,					\
-		__sysfs_bin_rw_handler_new * : NULL,			\
-		default : _write					\
-	),								\
-	.write_new = _Generic(_write,					\
-		__sysfs_bin_rw_handler_new * : _write,			\
-		default : NULL						\
-	),								\
+	.read = _read,							\
+	.write = _write,						\
 	.size	= _size,						\
 }