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authorAndi Kleen <andi@firstfloor.org>2010-01-15 20:01:16 -0500
committerLinus Torvalds <torvalds@linux-foundation.org>2010-01-16 15:15:38 -0500
commita5b9e2c1063046421ce01dcf5ddd7ec12567f3e1 (patch)
tree09cef2a043af96491497db380abe89af2aee5176 /kernel
parent64ce1037c5434b1d036cd99ecaee6e00496bc2e9 (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>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/kfifo.c21
1 files changed, 21 insertions, 0 deletions
diff --git a/kernel/kfifo.c b/kernel/kfifo.c
index b50bb622e8b..7384f120be8 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)
302} 302}
303EXPORT_SYMBOL(kfifo_out); 303EXPORT_SYMBOL(kfifo_out);
304 304
305/**
306 * kfifo_out_peek - copy some data from the FIFO, but do not remove it
307 * @fifo: the fifo to be used.
308 * @to: where the data must be copied.
309 * @len: the size of the destination buffer.
310 * @offset: offset into the fifo
311 *
312 * This function copies at most @len bytes at @offset from the FIFO
313 * into the @to buffer and returns the number of copied bytes.
314 * The data is not removed from the FIFO.
315 */
316unsigned int kfifo_out_peek(struct kfifo *fifo, void *to, unsigned int len,
317 unsigned offset)
318{
319 len = min(kfifo_len(fifo), len + offset);
320
321 __kfifo_out_data(fifo, to, len, offset);
322 return len;
323}
324EXPORT_SYMBOL(kfifo_out_peek);
325
305unsigned int __kfifo_out_generic(struct kfifo *fifo, 326unsigned int __kfifo_out_generic(struct kfifo *fifo,
306 void *to, unsigned int len, unsigned int recsize, 327 void *to, unsigned int len, unsigned int recsize,
307 unsigned int *total) 328 unsigned int *total)