hv: do not lose pending heartbeat vmbus packets

commit 407a3aee6ee2d2cb46d9ba3fc380bc29f35d020c upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/hv/hv_util.c b/drivers/hv/hv_util.c
index 3b9c9ef0deb8788da071344a4948c933100e9529..2d1414d07305476dfd8f5a4d2e07afab3ced2f19 100644 (file)
--- 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)];