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Subject[PATCH 2/2] vmbus: make hv_get_ringbuffer_availbytes local
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From: Stephen Hemminger <stephen@networkplumber.org>

hv_get_ringbuffer_availbytes is only used by the debug info
routine so make it static. Also, add READ_ONCE() to avoid any
possible issues with potentially volatile index values.

Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
---
drivers/hv/ring_buffer.c | 23 +++++++++++++++++++++++
include/linux/hyperv.h | 22 ----------------------
2 files changed, 23 insertions(+), 22 deletions(-)

diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
index 12eb8ca..50e0714 100644
--- a/drivers/hv/ring_buffer.c
+++ b/drivers/hv/ring_buffer.c
@@ -140,6 +140,29 @@ static u32 hv_copyto_ringbuffer(
return start_write_offset;
}

+/*
+ *
+ * hv_get_ringbuffer_availbytes()
+ *
+ * Get number of bytes available to read and to write to
+ * for the specified ring buffer
+ */
+static void
+hv_get_ringbuffer_availbytes(const struct hv_ring_buffer_info *rbi,
+ u32 *read, u32 *write)
+{
+ u32 read_loc, write_loc, dsize;
+
+ /* Capture the read/write indices before they changed */
+ read_loc = READ_ONCE(rbi->ring_buffer->read_index);
+ write_loc = READ_ONCE(rbi->ring_buffer->write_index);
+ dsize = rbi->ring_datasize;
+
+ *write = write_loc >= read_loc ? dsize - (write_loc - read_loc) :
+ read_loc - write_loc;
+ *read = dsize - *write;
+}
+
/* Get various debug metrics for the specified ring buffer. */
void hv_ringbuffer_get_debuginfo(const struct hv_ring_buffer_info *ring_info,
struct hv_ring_buffer_debug_info *debug_info)
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index 6c93366..93bd6fc 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -127,28 +127,6 @@ struct hv_ring_buffer_info {
u32 priv_read_index;
};

-/*
- *
- * hv_get_ringbuffer_availbytes()
- *
- * Get number of bytes available to read and to write to
- * for the specified ring buffer
- */
-static inline void
-hv_get_ringbuffer_availbytes(const struct hv_ring_buffer_info *rbi,
- u32 *read, u32 *write)
-{
- u32 read_loc, write_loc, dsize;
-
- /* Capture the read/write indices before they changed */
- read_loc = rbi->ring_buffer->read_index;
- write_loc = rbi->ring_buffer->write_index;
- dsize = rbi->ring_datasize;
-
- *write = write_loc >= read_loc ? dsize - (write_loc - read_loc) :
- read_loc - write_loc;
- *read = dsize - *write;
-}

static inline u32 hv_get_bytes_to_read(const struct hv_ring_buffer_info *rbi)
{
--
1.7.1
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