kfifo: add kfifo_out_peek

In some upcoming code it's useful to peek into a FIFO without permanentely
removing data.  This patch implements a new kfifo_out_peek() to do this.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Stefani Seibold <stefani@seibold.net>
Cc: Roland Dreier <rdreier@cisco.com>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Andy Walls <awalls@radix.net>
Cc: Vikram Dhillon <dhillonv10@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/kfifo.h b/include/linux/kfifo.h
index 86ad50a900c8..7ad6d32dd673 100644
--- a/include/linux/kfifo.h
+++ b/include/linux/kfifo.h
@@ -113,6 +113,9 @@ extern unsigned int kfifo_in(struct kfifo *fifo,
                                 const void *from, unsigned int len);
 extern __must_check unsigned int kfifo_out(struct kfifo *fifo,
                                 void *to, unsigned int len);
+extern __must_check unsigned int kfifo_out_peek(struct kfifo *fifo,
+                                void *to, unsigned int len, unsigned offset);
+
 
 /**
  * kfifo_reset - removes the entire FIFO contents