From 230fe9c7d8141d846ee9d30fd67204a44fc53943 Mon Sep 17 00:00:00 2001 From: Vineeth Remanan Pillai Date: Thu, 19 Jan 2017 08:35:39 -0800 Subject: [PATCH] xen-netfront: Fix Rx stall during network stress and OOM [ Upstream commit 90c311b0eeead647b708a723dbdde1eda3dcad05 ] During an OOM scenario, request slots could not be created as skb allocation fails. So the netback cannot pass in packets and netfront wrongly assumes that there is no more work to be done and it disables polling. This causes Rx to stall. The issue is with the retry logic which schedules the timer if the created slots are less than NET_RX_SLOTS_MIN. The count of new request slots to be pushed are calculated as a difference between new req_prod and rsp_cons which could be more than the actual slots, if there are unconsumed responses. The fix is to calculate the count of newly created slots as the difference between new req_prod and old req_prod. Signed-off-by: Vineeth Remanan Pillai Reviewed-by: Juergen Gross Signed-off-by: David S. Miller Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/net/xen-netfront.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c index 888e9cfef51a..34a062ccb11d 100644 --- a/drivers/net/xen-netfront.c +++ b/drivers/net/xen-netfront.c @@ -321,7 +321,7 @@ static void xennet_alloc_rx_buffers(struct netfront_queue *queue) queue->rx.req_prod_pvt = req_prod; /* Not enough requests? Try again later. */ - if (req_prod - queue->rx.rsp_cons < NET_RX_SLOTS_MIN) { + if (req_prod - queue->rx.sring->req_prod < NET_RX_SLOTS_MIN) { mod_timer(&queue->rx_refill_timer, jiffies + (HZ/10)); return; } -- 2.20.1