Merge branch 'perf/core' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux...

[safe/jmp/linux-2.6] / kernel / kfifo.c

diff --git a/kernel/kfifo.c b/kernel/kfifo.c
index b50bb62..35edbe2 100644 (file)
--- a/kernel/kfifo.c
+++ b/kernel/kfifo.c
@@ -41,7 +41,7 @@ static void _kfifo_init(struct kfifo *fifo, void *buffer,
  * kfifo_init - initialize a FIFO using a preallocated buffer
  * @fifo: the fifo to assign the buffer
  * @buffer: the preallocated buffer to be used.
- * @size: the size of the internal buffer, this have to be a power of 2.
+ * @size: the size of the internal buffer, this has to be a power of 2.
  *
  */
 void kfifo_init(struct kfifo *fifo, void *buffer, unsigned int size)
@@ -80,7 +80,7 @@ int kfifo_alloc(struct kfifo *fifo, unsigned int size, gfp_t gfp_mask)
 
        buffer = kmalloc(size, gfp_mask);
        if (!buffer) {
-               _kfifo_init(fifo, 0, 0);
+               _kfifo_init(fifo, NULL, 0);
                return -ENOMEM;
        }
 
@@ -97,6 +97,7 @@ EXPORT_SYMBOL(kfifo_alloc);
 void kfifo_free(struct kfifo *fifo)
 {
        kfree(fifo->buffer);
+       _kfifo_init(fifo, NULL, 0);
 }
 EXPORT_SYMBOL(kfifo_free);
 
@@ -302,6 +303,27 @@ 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)
@@ -328,6 +350,7 @@ EXPORT_SYMBOL(__kfifo_from_user_n);
  * @fifo: the fifo to be used.
  * @from: pointer to the data to be added.
  * @len: the length of the data to be added.
+ * @total: the actual returned data length.
  *
  * This function copies at most @len bytes from the @from into the
  * FIFO depending and returns -EFAULT/0.
@@ -378,7 +401,7 @@ EXPORT_SYMBOL(__kfifo_to_user_n);
  * @fifo: the fifo to be used.
  * @to: where the data must be copied.
  * @len: the size of the destination buffer.
- @ @lenout: pointer to output variable with copied data
+ * @lenout: pointer to output variable with copied data
  *
  * This function copies at most @len bytes from the FIFO into the
  * @to buffer and 0 or -EFAULT.