vmxnet3: prevent receive getting out of sequence on napi poll

Orabug: 25639933

vmxnet3's current napi path is built to count every rx descriptor we recieve,
and use that as a count of the napi budget.  That means its possible to return
from a napi poll halfway through recieving a fragmented packet accross multiple
dma descriptors.  If that happens, the next napi poll will start with the
descriptor ring in an improper state (e.g. the first descriptor we look at may
have the end-of-packet bit set), which will cause a BUG halt in the driver.

Fix the issue by only counting whole received packets in the napi poll and
returning that value, rather than the descriptor count.

Tested by the reporter and myself, successfully

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
CC: Shreyas Bhatewara <sbhatewara@vmware.com>
CC: "David S. Miller" <davem@davemloft.net>
Acked-by: Andy Gospodarek <gospo@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit 0769636cb5b95665ebadcd1a41c46f331f5a397d)
Signed-off-by: Brian Maly <brian.maly@oracle.com>

diff --git a/drivers/net/vmxnet3/vmxnet3_drv.c b/drivers/net/vmxnet3/vmxnet3_drv.c
index 903dcaae07a135add90d75c91786229d8d259b58..05c809640a62f33af1d44066c17afbade910096b 100644 (file)
--- a/drivers/net/vmxnet3/vmxnet3_drv.c
+++ b/drivers/net/vmxnet3/vmxnet3_drv.c
@@ -1220,7 +1220,7 @@ vmxnet3_rq_rx_complete(struct vmxnet3_rx_queue *rq,
        static const u32 rxprod_reg[2] = {
                VMXNET3_REG_RXPROD, VMXNET3_REG_RXPROD2
        };
-       u32 num_rxd = 0;
+       u32 num_pkts = 0;
        bool skip_page_frags = false;
        struct Vmxnet3_RxCompDesc *rcd;
        struct vmxnet3_rx_ctx *ctx = &rq->rx_ctx;
@@ -1239,13 +1239,12 @@ vmxnet3_rq_rx_complete(struct vmxnet3_rx_queue *rq,
                struct Vmxnet3_RxDesc *rxd;
                u32 idx, ring_idx;
                struct vmxnet3_cmd_ring *ring = NULL;
-               if (num_rxd >= quota) {
+               if (num_pkts >= quota) {
                        /* we may stop even before we see the EOP desc of
                         * the current pkt
                         */
                        break;
                }
-               num_rxd++;
                BUG_ON(rcd->rqID != rq->qid && rcd->rqID != rq->qid2);
                idx = rcd->rxdIdx;
                ring_idx = rcd->rqID < adapter->num_rx_queues ? 0 : 1;
@@ -1417,6 +1416,7 @@ not_lro:
                                napi_gro_receive(&rq->napi, skb);
 
                        ctx->skb = NULL;
+                       num_pkts++;
                }
 
 rcd_done:
@@ -1447,7 +1447,7 @@ rcd_done:
                                  &rq->comp_ring.base[rq->comp_ring.next2proc].rcd, &rxComp);
        }
 
-       return num_rxd;
+       return num_pkts;
 }