kfifo: Use "const" definitions

Currently kfifo cannot be used by parts of the kernel that use "const"
properly as kfifo itself does not use const for passed data blocks which
are indeed const.
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

include/linux/kfifo.h

@@ -38,7 +38,7 @@ extern struct kfifo *kfifo_alloc(unsigned int size, gfp_t gfp_mask,
 				 spinlock_t *lock);
 extern void kfifo_free(struct kfifo *fifo);
 extern unsigned int __kfifo_put(struct kfifo *fifo,
-				unsigned char *buffer, unsigned int len);
+				const unsigned char *buffer, unsigned int len);
 extern unsigned int __kfifo_get(struct kfifo *fifo,
 				unsigned char *buffer, unsigned int len);
 
@@ -77,7 +77,7 @@ static inline void kfifo_reset(struct kfifo *fifo)
  * bytes copied.
  */
 static inline unsigned int kfifo_put(struct kfifo *fifo,
-				     unsigned char *buffer, unsigned int len)
+				const unsigned char *buffer, unsigned int len)
 {
 	unsigned long flags;
 	unsigned int ret;

kernel/kfifo.c

@@ -117,7 +117,7 @@ EXPORT_SYMBOL(kfifo_free);
  * writer, you don't need extra locking to use these functions.
  */
 unsigned int __kfifo_put(struct kfifo *fifo,
-			 unsigned char *buffer, unsigned int len)
+			const unsigned char *buffer, unsigned int len)
 {
 	unsigned int l;