vmbus: constify parameters where possible

Functions that just query state of ring buffer can have parameters
marked const.

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

drivers/hv/hyperv_vmbus.h

@@ -283,14 +283,14 @@ int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info,
 void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info);
 
 int hv_ringbuffer_write(struct vmbus_channel *channel,
-			struct kvec *kv_list, u32 kv_count);
+			const struct kvec *kv_list, u32 kv_count);
 
 int hv_ringbuffer_read(struct vmbus_channel *channel,
 		       void *buffer, u32 buflen, u32 *buffer_actual_len,
 		       u64 *requestid, bool raw);
 
-void hv_ringbuffer_get_debuginfo(struct hv_ring_buffer_info *ring_info,
-			    struct hv_ring_buffer_debug_info *debug_info);
+void hv_ringbuffer_get_debuginfo(const struct hv_ring_buffer_info *ring_info,
+				 struct hv_ring_buffer_debug_info *debug_info);
 
 /*
  * Maximum channels is determined by the size of the interrupt page

drivers/hv/ring_buffer.c

@@ -96,11 +96,9 @@ hv_set_next_write_location(struct hv_ring_buffer_info *ring_info,
 
 /* Get the next read location for the specified ring buffer. */
 static inline u32
-hv_get_next_read_location(struct hv_ring_buffer_info *ring_info)
+hv_get_next_read_location(const struct hv_ring_buffer_info *ring_info)
 {
-	u32 next = ring_info->ring_buffer->read_index;
-
-	return next;
+	return ring_info->ring_buffer->read_index;
 }
 
 /*
@@ -108,8 +106,8 @@ hv_get_next_read_location(struct hv_ring_buffer_info *ring_info)
  * This allows the caller to skip.
  */
 static inline u32
-hv_get_next_readlocation_withoffset(struct hv_ring_buffer_info *ring_info,
-				 u32 offset)
+hv_get_next_readlocation_withoffset(const struct hv_ring_buffer_info *ring_info,
+				    u32 offset)
 {
 	u32 next = ring_info->ring_buffer->read_index;
 
@@ -130,7 +128,7 @@ hv_set_next_read_location(struct hv_ring_buffer_info *ring_info,
 
 /* Get the size of the ring buffer. */
 static inline u32
-hv_get_ring_buffersize(struct hv_ring_buffer_info *ring_info)
+hv_get_ring_buffersize(const struct hv_ring_buffer_info *ring_info)
 {
 	return ring_info->ring_datasize;
 }
@@ -147,7 +145,7 @@ hv_get_ring_bufferindices(struct hv_ring_buffer_info *ring_info)
  * Assume there is enough room. Handles wrap-around in src case only!!
  */
 static u32 hv_copyfrom_ringbuffer(
-	struct hv_ring_buffer_info	*ring_info,
+	const struct hv_ring_buffer_info *ring_info,
 	void				*dest,
 	u32				destlen,
 	u32				start_read_offset)
@@ -171,7 +169,7 @@ static u32 hv_copyfrom_ringbuffer(
 static u32 hv_copyto_ringbuffer(
 	struct hv_ring_buffer_info	*ring_info,
 	u32				start_write_offset,
-	void				*src,
+	const void			*src,
 	u32				srclen)
 {
 	void *ring_buffer = hv_get_ring_buffer(ring_info);
@@ -186,8 +184,8 @@ static u32 hv_copyto_ringbuffer(
 }
 
 /* Get various debug metrics for the specified ring buffer. */
-void hv_ringbuffer_get_debuginfo(struct hv_ring_buffer_info *ring_info,
-			    struct hv_ring_buffer_debug_info *debug_info)
+void hv_ringbuffer_get_debuginfo(const struct hv_ring_buffer_info *ring_info,
+				 struct hv_ring_buffer_debug_info *debug_info)
 {
 	u32 bytes_avail_towrite;
 	u32 bytes_avail_toread;
@@ -264,7 +262,7 @@ void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info)
 
 /* Write to the ring buffer. */
 int hv_ringbuffer_write(struct vmbus_channel *channel,
-			struct kvec *kv_list, u32 kv_count)
+			const struct kvec *kv_list, u32 kv_count)
 {
 	int i = 0;
 	u32 bytes_avail_towrite;

include/linux/hyperv.h

@@ -138,8 +138,8 @@ struct hv_ring_buffer_info {
  * for the specified ring buffer
  */
 static inline void
-hv_get_ringbuffer_availbytes(struct hv_ring_buffer_info *rbi,
-			  u32 *read, u32 *write)
+hv_get_ringbuffer_availbytes(const struct hv_ring_buffer_info *rbi,
+			     u32 *read, u32 *write)
 {
 	u32 read_loc, write_loc, dsize;
 
@@ -153,7 +153,7 @@ hv_get_ringbuffer_availbytes(struct hv_ring_buffer_info *rbi,
 	*read = dsize - *write;
 }
 
-static inline u32 hv_get_bytes_to_read(struct hv_ring_buffer_info *rbi)
+static inline u32 hv_get_bytes_to_read(const struct hv_ring_buffer_info *rbi)
 {
 	u32 read_loc, write_loc, dsize, read;
 
@@ -167,7 +167,7 @@ static inline u32 hv_get_bytes_to_read(struct hv_ring_buffer_info *rbi)
 	return read;
 }
 
-static inline u32 hv_get_bytes_to_write(struct hv_ring_buffer_info *rbi)
+static inline u32 hv_get_bytes_to_write(const struct hv_ring_buffer_info *rbi)
 {
 	u32 read_loc, write_loc, dsize, write;
 
@@ -1448,9 +1448,9 @@ void vmbus_set_event(struct vmbus_channel *channel);
 
 /* Get the start of the ring buffer. */
 static inline void *
-hv_get_ring_buffer(struct hv_ring_buffer_info *ring_info)
+hv_get_ring_buffer(const struct hv_ring_buffer_info *ring_info)
 {
-	return (void *)ring_info->ring_buffer->buffer;
+	return ring_info->ring_buffer->buffer;
 }
 
 /*