[SRU][Trusty][Vivid][Xenial][Yakkety][PATCH 1/1] hv: do not lose pending heartbeat vmbus packets

Joseph Salisbury joseph.salisbury at canonical.com
Thu Nov 10 20:51:50 UTC 2016

From: Long Li <longli at microsoft.com>

BugLink: http://bugs.launchpad.net/bugs/1632786

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 at microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys at microsoft.com>
CC: Stable <stable at vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
(cherry picked from commit 407a3aee6ee2d2cb46d9ba3fc380bc29f35d020c)
Signed-off-by: Joseph Salisbury <joseph.salisbury at canonical.com>
 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 d5acaa2..9dc6372 100644
--- a/drivers/hv/hv_util.c
+++ b/drivers/hv/hv_util.c
@@ -283,10 +283,14 @@ 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)];

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