[PATCH] [linux-4.9.y only] vmbus: fix missing signaling in hv_signal_on_read()

[PATCH] [linux-4.9.y only] vmbus: fix missing signaling in hv_signal_on_read()

[Dexuan Cui]

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>
---

Hi Greg, as we discussed, I'm resending this patch, and please only apply
it to linux-4.9.y (i.e. v4.9.57 as of today).

 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 d596a07..8cc99de 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;
-- 
1.9.1

Patch "vmbus: fix missing signaling in hv_signal_on_read()" has been added to the 4.9-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    vmbus: fix missing signaling in hv_signal_on_read()

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     vmbus-fix-missing-signaling-in-hv_signal_on_read.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From decui@microsoft.com  Tue Oct 24 14:15:52 2017
From: Dexuan Cui <decui@microsoft.com>
Date: Thu, 19 Oct 2017 18:07:35 +0000
Subject: vmbus: fix missing signaling in hv_signal_on_read()
To: "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>, "stable@vger.kernel.org" <stable@vger.kernel.org>
Cc: KY Srinivasan <kys@microsoft.com>, Stephen Hemminger <stephen@networkplumber.org>, Stephen Hemminger <sthemmin@microsoft.com>
Message-ID: <KL1P15301MB00062D18DE80DE90B4116AB4BF420@KL1P15301MB0006.APCP153.PROD.OUTLOOK.COM>

From: Dexuan Cui <decui@microsoft.com>

[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>
---

Hi Greg, as we discussed, I'm resending this patch, and please only apply
it to linux-4.9.y (i.e. v4.9.57 as of today).

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

--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -1521,11 +1521,11 @@ static inline  void hv_signal_on_read(st
 
 	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;


Patches currently in stable-queue which might be from decui@microsoft.com are

queue-4.9/vmbus-fix-missing-signaling-in-hv_signal_on_read.patch