3.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: "K. Y. Srinivasan" <kys@xxxxxxxxxxxxx>
commit 288fa3e022eb85fa151e0f9bcd15caeb81679af6 upstream.
As part of updating the vmbus protocol, the function hv_need_to_signal()
was introduced. This functions helps optimize signalling from guest to
host. The newly added memory barrier is needed to ensure that we correctly
decide when to signal the host.
Signed-off-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
Reviewed-by: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
Reported-by: Olaf Hering <olh@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/hv/ring_buffer.c | 1 +
1 file changed, 1 insertion(+)
--- a/drivers/hv/ring_buffer.c
+++ b/drivers/hv/ring_buffer.c
@@ -71,6 +71,7 @@ u32 hv_end_read(struct hv_ring_buffer_in
static bool hv_need_to_signal(u32 old_write, struct hv_ring_buffer_info *rbi)
{
+ smp_mb();
if (rbi->ring_buffer->interrupt_mask)
return false;
--
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