patch "hv: do not lose pending heartbeat vmbus packets" added to char-misc-linus

patch "hv: do not lose pending heartbeat vmbus packets" added to char-misc-linus

[gregkh]

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

    hv: do not lose pending heartbeat vmbus packets

to my char-misc git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git
in the char-misc-linus branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.

If you have any questions about this process, please let me know.


>From 407a3aee6ee2d2cb46d9ba3fc380bc29f35d020c Mon Sep 17 00:00:00 2001
From: Long Li <longli@microsoft.com>
Date: Wed, 5 Oct 2016 16:57:46 -0700
Subject: hv: do not lose pending heartbeat vmbus packets

The host keeps sending heartbeat packets independent of the
guest responding to them.  Even though we respond to the heartbeat messages at
interrupt level, we can have situations where there maybe multiple heartbeat
messages pending that have not been responded to. For instance this occurs when the
VM is paused and the host continues to send the heartbeat messages.
Address this issue by draining and responding to all
the heartbeat messages that maybe pending.

Signed-off-by: Long Li <longli@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
CC: Stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/hv/hv_util.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/hv/hv_util.c b/drivers/hv/hv_util.c
index 4aa3cb63fd41..bcd06306f3e8 100644
--- a/drivers/hv/hv_util.c
+++ b/drivers/hv/hv_util.c
@@ -314,10 +314,14 @@ static void heartbeat_onchannelcallback(void *context)
 	u8 *hbeat_txf_buf = util_heartbeat.recv_buffer;
 	struct icmsg_negotiate *negop = NULL;
 
-	vmbus_recvpacket(channel, hbeat_txf_buf,
-			 PAGE_SIZE, &recvlen, &requestid);
+	while (1) {
+
+		vmbus_recvpacket(channel, hbeat_txf_buf,
+				 PAGE_SIZE, &recvlen, &requestid);
+
+		if (!recvlen)
+			break;
 
-	if (recvlen > 0) {
 		icmsghdrp = (struct icmsg_hdr *)&hbeat_txf_buf[
 				sizeof(struct vmbuspipe_hdr)];
 
-- 
2.10.1