qlcnic: fix race in tx stop queue

There is a race between netif_stop_queue and netif_stopped_queue
check. So check once again if buffers are available to avoid race.
With above logic we can also get rid of tx lock in process_cmd_ring.

Signed-off-by: Rajesh K Borundia <rajesh.borundia@qlogic.com>
Signed-off-by: Amit Kumar Salecha <amit.salecha@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 3 deletions

diff --git a/drivers/net/qlcnic/qlcnic_hw.c b/drivers/net/qlcnic/qlcnic_hw.c
index f776956d2d6c..d9becb96d403 100644
--- a/drivers/net/qlcnic/qlcnic_hw.c
+++ b/drivers/net/qlcnic/qlcnic_hw.c
@@ -338,9 +338,15 @@ qlcnic_send_cmd_descs(struct qlcnic_adapter *adapter,
 
         if (nr_desc >= qlcnic_tx_avail(tx_ring)) {
                 netif_tx_stop_queue(tx_ring->txq);
-                __netif_tx_unlock_bh(tx_ring->txq);
-                adapter->stats.xmit_off++;
-                return -EBUSY;
+                smp_mb();
+                if (qlcnic_tx_avail(tx_ring) > nr_desc) {
+                        if (qlcnic_tx_avail(tx_ring) > TX_STOP_THRESH)
+                                netif_tx_wake_queue(tx_ring->txq);
+                } else {
+                        adapter->stats.xmit_off++;
+                        __netif_tx_unlock_bh(tx_ring->txq);
+                        return -EBUSY;
+                }
         }
 
         do {