diff options
| author | Andi Kleen <andi@firstfloor.org> | 2010-01-15 17:01:16 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-01-16 12:15:38 -0800 |
| commit | a5b9e2c1063046421ce01dcf5ddd7ec12567f3e1 (patch) | |
| tree | 09cef2a043af96491497db380abe89af2aee5176 | |
| parent | 64ce1037c5434b1d036cd99ecaee6e00496bc2e9 (diff) | |
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>
| -rw-r--r-- | include/linux/kfifo.h | 3 | ||||
| -rw-r--r-- | kernel/kfifo.c | 21 |
2 files changed, 24 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 diff --git a/kernel/kfifo.c b/kernel/kfifo.c index b50bb622e8b0..7384f120be87 100644 --- a/kernel/kfifo.c +++ b/kernel/kfifo.c @@ -302,6 +302,27 @@ unsigned int kfifo_out(struct kfifo *fifo, void *to, unsigned int len) } EXPORT_SYMBOL(kfifo_out); +/** + * kfifo_out_peek - copy some data from the FIFO, but do not remove it + * @fifo: the fifo to be used. + * @to: where the data must be copied. + * @len: the size of the destination buffer. + * @offset: offset into the fifo + * + * This function copies at most @len bytes at @offset from the FIFO + * into the @to buffer and returns the number of copied bytes. + * The data is not removed from the FIFO. + */ +unsigned int kfifo_out_peek(struct kfifo *fifo, void *to, unsigned int len, + unsigned offset) +{ + len = min(kfifo_len(fifo), len + offset); + + __kfifo_out_data(fifo, to, len, offset); + return len; +} +EXPORT_SYMBOL(kfifo_out_peek); + unsigned int __kfifo_out_generic(struct kfifo *fifo, void *to, unsigned int len, unsigned int recsize, unsigned int *total) |