net: macb: Fix race condition in driver when Rx frame is dropped

Under heavy Rx load, observed that the Hw is updating the USED bit
and it is not updating the received frame status to the BD control
field. This could be lack of resources for processing the BDs at high
data rates. Driver drops the frame associated with this BD but not
clearing the USED bit. So, this is causing hang condition as Hw
expects USED bit to be cleared for this BD.

Signed-off-by: Punnaiah Choudary Kalluri <punnaia@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>

diff --git a/drivers/net/ethernet/cadence/macb.c b/drivers/net/ethernet/cadence/macb.c
index caa94a1b8a0db8cfbb87235b41e26ca004dae60f..48522a0232436c0d017d1c9ce0d3972096bd88cb 100644 (file)
--- a/drivers/net/ethernet/cadence/macb.c
+++ b/drivers/net/ethernet/cadence/macb.c
@@ -707,6 +707,9 @@ static void gem_rx_refill(struct macb *bp)
 
                        /* properly align Ethernet header */
                        skb_reserve(skb, NET_IP_ALIGN);
+               } else {
+                       bp->rx_ring[entry].addr &= ~MACB_BIT(RX_USED);
+                       bp->rx_ring[entry].ctrl = 0;
                }
        }