From: Dexuan Cui <decui@microsoft.com>
Date: Thu, 19 Oct 2017 18:07:35 +0000 (+0000)
Subject: vmbus: fix missing signaling in hv_signal_on_read()
X-Git-Tag: archive/raspbian/4.9.80-2+rpi1~7^2~1550
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=13c5e97701091f9b02ded0c68809f8a6b08c747a;p=linux-4.9.git

vmbus: fix missing signaling in hv_signal_on_read()

[Fixes upstream in a much larger set of patches that are not worth backporting
to 4.9 - gregkh]

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@microsoft.com>
Signed-off-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index d596a076da11..8cc99de27bc2 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -1521,11 +1521,11 @@ 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);
 
 	return;