Staging: hv: vmbus: Fix the memory barrier in hv_ringbuffer_read()

Use the correct barrier interface.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Abhishek Kane <v-abkane@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/hv/ring_buffer.c

@@ -513,7 +513,7 @@ int hv_ringbuffer_read(struct hv_ring_buffer_info *inring_info, void *buffer,
 	/* Make sure all reads are done before we update the read index since */
 	/* the writer may start writing to the read area once the read index */
 	/*is updated */
-	mb();
+	smp_mb();
 
 	/* Update the read index */
 	hv_set_next_read_location(inring_info, next_read_location);