[PATCH 3/4] Drivers: hv: ring_buffer: use wrap around mappings in hv_copy{from,to}_ringbuffer()

From: Vitaly Kuznetsov
Date: Fri Jun 10 2016 - 05:47:58 EST


With wrap around mappings for ring buffers we can always use a single
memcpy() to do the job.

Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
---
drivers/hv/ring_buffer.c | 24 +++---------------------
1 file changed, 3 insertions(+), 21 deletions(-)

diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
index a84c45a..53e912a 100644
--- a/drivers/hv/ring_buffer.c
+++ b/drivers/hv/ring_buffer.c
@@ -164,18 +164,7 @@ static u32 hv_copyfrom_ringbuffer(
void *ring_buffer = hv_get_ring_buffer(ring_info);
u32 ring_buffer_size = hv_get_ring_buffersize(ring_info);

- u32 frag_len;
-
- /* wrap-around detected at the src */
- if (destlen > ring_buffer_size - start_read_offset) {
- frag_len = ring_buffer_size - start_read_offset;
-
- memcpy(dest, ring_buffer + start_read_offset, frag_len);
- memcpy(dest + frag_len, ring_buffer, destlen - frag_len);
- } else
-
- memcpy(dest, ring_buffer + start_read_offset, destlen);
-
+ memcpy(dest, ring_buffer + start_read_offset, destlen);

start_read_offset += destlen;
start_read_offset %= ring_buffer_size;
@@ -196,15 +185,8 @@ static u32 hv_copyto_ringbuffer(
{
void *ring_buffer = hv_get_ring_buffer(ring_info);
u32 ring_buffer_size = hv_get_ring_buffersize(ring_info);
- u32 frag_len;
-
- /* wrap-around detected! */
- if (srclen > ring_buffer_size - start_write_offset) {
- frag_len = ring_buffer_size - start_write_offset;
- memcpy(ring_buffer + start_write_offset, src, frag_len);
- memcpy(ring_buffer, src + frag_len, srclen - frag_len);
- } else
- memcpy(ring_buffer + start_write_offset, src, srclen);
+
+ memcpy(ring_buffer + start_write_offset, src, srclen);

start_write_offset += srclen;
start_write_offset %= ring_buffer_size;
--
2.5.5