linux-kernel - [PATCH] vmbus: fix missing signaling in hv_signal_on

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Message-Id: <20170816154946.7495-1-sthemmin@microsoft.com>
Date:   Wed, 16 Aug 2017 08:49:46 -0700
From:   Stephen Hemminger <stephen@...workplumber.org>
To:     kys@...rosoft.com, decui@...rosoft.com
Cc:     devel@...uxdriverproject.org, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org, Stephen Hemminger <sthemmin@...rosoft.com>,
        John Starks <jon.Starks@...rosoft.com>
Subject: [PATCH] vmbus: fix missing signaling in hv_signal_on_read()

When the space available before start of reading (cached_write_sz)
is the same as the host required space (pending_sz), we need to
still signal host.

Fixes: 433e19cf33d3 ("Drivers: hv: vmbus: finally fix hv_need_to_signal_on_read()")

Signed-off-by: John Starks <jon.Starks@...rosoft.com>
Signed-off-by: Dexuan Cui <decui@...rosoft.com>
Signed-off-by: Stephen Hemminger <sthemmin@...rosoft.com>
---
This patch is for 4.13 (and stable).
A different fix is needed for linux-next.

 include/linux/hyperv.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index e09fc8290c2f..080a0797c6f3 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -1515,11 +1515,11 @@ static inline  void hv_signal_on_read(struct vmbus_channel *channel)
 
 	cur_write_sz = hv_get_bytes_to_write(rbi);
 
-	if (cur_write_sz < pending_sz)
+	if (cur_write_sz <= pending_sz)
 		return;
 
 	cached_write_sz = hv_get_cached_bytes_to_write(rbi);
-	if (cached_write_sz < pending_sz)
+	if (cached_write_sz <= pending_sz)
 		vmbus_setevent(channel);
 }
 
-- 
2.11.0