On 05/04/2013 01:18 AM, gregkh@xxxxxxxxxxxxxxxxxxx wrote:
The patch below does not apply to the 3.8-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 288fa3e022eb85fa151e0f9bcd15caeb81679af6 Mon Sep 17 00:00:00 2001
From: "K. Y. Srinivasan" <kys@xxxxxxxxxxxxx>
Date: Fri, 29 Mar 2013 14:30:38 -0700
Subject: [PATCH] Drivers: hv: vmbus: Fix a bug in hv_need_to_signal()
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>
Cc: Stable <stable@xxxxxxxxxxxxxxx> (V3.8+)
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
index cafa72f..d6fbb577 100644
--- a/drivers/hv/ring_buffer.c
+++ b/drivers/hv/ring_buffer.c
@@ -71,6 +71,7 @@ u32 hv_end_read(struct hv_ring_buffer_info *rbi)
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;
This patch isn't needed for 3.8-stable.
hv_need_to_signal() is added in 3.9-rc1 and not present in 3.8-stable.
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