diff mbox series

[b:azure-4.15,f:azure,2/2] hv_utils: drain the timesync packets on onchannelcallback

Message ID 20201216001223.463961-3-kelsey.skunberg@canonical.com
State New
Headers show
Series Keep Chrony time in sync | expand

Commit Message

Kelsey Skunberg Dec. 16, 2020, 12:12 a.m. UTC 
From: Vineeth Pillai <viremana@linux.microsoft.com>

BugLink: https://bugs.launchpad.net/bugs/1896784

There could be instances where a system stall prevents the timesync
packets to be consumed. And this might lead to more than one packet
pending in the ring buffer. Current code empties one packet per callback
and it might be a stale one. So drain all the packets from ring buffer
on each callback.

Signed-off-by: Vineeth Pillai <viremana@linux.microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20200821152849.99517-1-viremana@linux.microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
(backported from commit b46b4a8a57c377b72a98c7930a9f6969d2d4784e)
[KelseyS: HV_HYP_PAGE_SIZE changed to PAGE_SIZE]
Signed-off-by: Kelsey Skunberg <kelsey.skunberg@canonical.com>
---
 drivers/hv/hv_util.c | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/drivers/hv/hv_util.c b/drivers/hv/hv_util.c
index a395f50b3ca2..2c9dabf64184 100644
--- a/drivers/hv/hv_util.c
+++ b/drivers/hv/hv_util.c
@@ -387,10 +387,22 @@  static void timesync_onchannelcallback(void *context)
 	struct ictimesync_ref_data *refdata;
 	u8 *time_txf_buf = util_timesynch.recv_buffer;
 
-	vmbus_recvpacket(channel, time_txf_buf,
-			 PAGE_SIZE, &recvlen, &requestid);
+	/*
+	 * Drain the ring buffer and use the last packet to update
+	 * host_ts
+	 */
+	while (1) {
+		int ret = vmbus_recvpacket(channel, time_txf_buf,
+					   PAGE_SIZE, &recvlen, &requestid);
+		if (ret) {
+			pr_warn_once("TimeSync IC pkt recv failed (Err: %d)\n",
+				     ret);
+			break;
+		}
+
+		if (!recvlen)
+			break;
 
-	if (recvlen > 0) {
 		icmsghdrp = (struct icmsg_hdr *)&time_txf_buf[
 				sizeof(struct vmbuspipe_hdr)];