Drivers: hv: vmbus: Cleanup the packet send path

The current channel code is using scatterlist abstraction to pass data to the
ringbuffer API on the send path. This causes unnecessary translations
between virtual and physical addresses. Fix this.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 7 insertions, 10 deletions

diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
index 26c93cf9f6be..15db66b74141 100644
--- a/drivers/hv/ring_buffer.c
+++ b/drivers/hv/ring_buffer.c
@@ -26,6 +26,7 @@
 #include <linux/kernel.h>
 #include <linux/mm.h>
 #include <linux/hyperv.h>
+#include <linux/uio.h>
 
 #include "hyperv_vmbus.h"
 
@@ -387,23 +388,20 @@ void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info)
  *
  */
 int hv_ringbuffer_write(struct hv_ring_buffer_info *outring_info,
-                    struct scatterlist *sglist, u32 sgcount, bool *signal)
+                    struct kvec *kv_list, u32 kv_count, bool *signal)
 {
         int i = 0;
         u32 bytes_avail_towrite;
         u32 bytes_avail_toread;
         u32 totalbytes_towrite = 0;
 
-        struct scatterlist *sg;
         u32 next_write_location;
         u32 old_write;
         u64 prev_indices = 0;
         unsigned long flags;
 
-        for_each_sg(sglist, sg, sgcount, i)
-        {
-                totalbytes_towrite += sg->length;
-        }
+        for (i = 0; i < kv_count; i++)
+                totalbytes_towrite += kv_list[i].iov_len;
 
         totalbytes_towrite += sizeof(u64);
 
@@ -427,12 +425,11 @@ int hv_ringbuffer_write(struct hv_ring_buffer_info *outring_info,
 
         old_write = next_write_location;
 
-        for_each_sg(sglist, sg, sgcount, i)
-        {
+        for (i = 0; i < kv_count; i++) {
                 next_write_location = hv_copyto_ringbuffer(outring_info,
                                                      next_write_location,
-                                                     sg_virt(sg),
-                                                     sg->length);
+                                                     kv_list[i].iov_base,
+                                                     kv_list[i].iov_len);
         }
 
         /* Set previous packet start */