From: Vineeth Remanan Pillai vineethp@amazon.com
commit 538d92912d3190a1dd809233a0d57277459f37b2 upstream.
The commit 90c311b0eeea ("xen-netfront: Fix Rx stall during network stress and OOM") caused the refill timer to be triggerred almost on all invocations of xennet_alloc_rx_buffers for certain workloads. This reworks the fix by reverting to the old behaviour and taking into consideration the skb allocation failure. Refill timer is now triggered on insufficient requests or skb allocation failure.
Signed-off-by: Vineeth Remanan Pillai vineethp@amazon.com Fixes: 90c311b0eeea (xen-netfront: Fix Rx stall during network stress and OOM) Reported-by: Boris Ostrovsky boris.ostrovsky@oracle.com Reviewed-by: Boris Ostrovsky boris.ostrovsky@oracle.com Signed-off-by: David S. Miller davem@davemloft.net Cc: Guenter Roeck linux@roeck-us.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/net/xen-netfront.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-)
--- a/drivers/net/xen-netfront.c +++ b/drivers/net/xen-netfront.c @@ -283,6 +283,7 @@ static void xennet_alloc_rx_buffers(stru { RING_IDX req_prod = queue->rx.req_prod_pvt; int notify; + int err = 0;
if (unlikely(!netif_carrier_ok(queue->info->netdev))) return; @@ -297,8 +298,10 @@ static void xennet_alloc_rx_buffers(stru struct xen_netif_rx_request *req;
skb = xennet_alloc_one_rx_buffer(queue); - if (!skb) + if (!skb) { + err = -ENOMEM; break; + }
id = xennet_rxidx(req_prod);
@@ -322,8 +325,13 @@ static void xennet_alloc_rx_buffers(stru
queue->rx.req_prod_pvt = req_prod;
- /* Not enough requests? Try again later. */ - if (req_prod - queue->rx.sring->req_prod < NET_RX_SLOTS_MIN) { + /* Try again later if there are not enough requests or skb allocation + * failed. + * Enough requests is quantified as the sum of newly created slots and + * the unconsumed slots at the backend. + */ + if (req_prod - queue->rx.rsp_cons < NET_RX_SLOTS_MIN || + unlikely(err)) { mod_timer(&queue->rx_refill_timer, jiffies + (HZ/10)); return; }