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>

4 files changed, 26 insertions, 19 deletions

diff --git a/drivers/net/qlcnic/qlcnic.h b/drivers/net/qlcnic/qlcnic.h
index 9970cff598d1..99ccdd8ac419 100644
--- a/drivers/net/qlcnic/qlcnic.h
+++ b/drivers/net/qlcnic/qlcnic.h
@@ -113,8 +113,10 @@
 #define TX_UDPV6_PKT    0x0c
 
 /* Tx defines */
-#define MAX_BUFFERS_PER_CMD     32
-#define TX_STOP_THRESH          ((MAX_SKB_FRAGS >> 2) + 4)
+#define MAX_TSO_HEADER_DESC     2
+#define MGMT_CMD_DESC_RESV      4
+#define TX_STOP_THRESH          ((MAX_SKB_FRAGS >> 2) + MAX_TSO_HEADER_DESC \
+                                                        + MGMT_CMD_DESC_RESV)
 #define QLCNIC_MAX_TX_TIMEOUTS  2
 
 /*
@@ -369,7 +371,7 @@ struct qlcnic_recv_crb {
  */
 struct qlcnic_cmd_buffer {
         struct sk_buff *skb;
-        struct qlcnic_skb_frag frag_array[MAX_BUFFERS_PER_CMD + 1];
+        struct qlcnic_skb_frag frag_array[MAX_SKB_FRAGS + 1];
         u32 frag_count;
 };
 
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 {
diff --git a/drivers/net/qlcnic/qlcnic_init.c b/drivers/net/qlcnic/qlcnic_init.c
index 2bd00d54dd3f..058ce61501c3 100644
--- a/drivers/net/qlcnic/qlcnic_init.c
+++ b/drivers/net/qlcnic/qlcnic_init.c
@@ -181,7 +181,9 @@ skip_rds:
 
         tx_ring = adapter->tx_ring;
         vfree(tx_ring->cmd_buf_arr);
+        tx_ring->cmd_buf_arr = NULL;
         kfree(adapter->tx_ring);
+        adapter->tx_ring = NULL;
 }
 
 int qlcnic_alloc_sw_resources(struct qlcnic_adapter *adapter)
diff --git a/drivers/net/qlcnic/qlcnic_main.c b/drivers/net/qlcnic/qlcnic_main.c
index 06d2dfd646fe..655bccd7f8f4 100644
--- a/drivers/net/qlcnic/qlcnic_main.c
+++ b/drivers/net/qlcnic/qlcnic_main.c
@@ -132,12 +132,6 @@ qlcnic_update_cmd_producer(struct qlcnic_adapter *adapter,
                 struct qlcnic_host_tx_ring *tx_ring)
 {
         writel(tx_ring->producer, tx_ring->crb_cmd_producer);
-
-        if (qlcnic_tx_avail(tx_ring) <= TX_STOP_THRESH) {
-                netif_stop_queue(adapter->netdev);
-                smp_mb();
-                adapter->stats.xmit_off++;
-        }
 }
 
 static const u32 msi_tgt_status[8] = {
@@ -1137,7 +1131,7 @@ qlcnic_setup_netdev(struct qlcnic_adapter *adapter,
         adapter->max_mc_count = 38;
 
         netdev->netdev_ops         = &qlcnic_netdev_ops;
-        netdev->watchdog_timeo     = 2*HZ;
+        netdev->watchdog_timeo     = 5*HZ;
 
         qlcnic_change_mtu(netdev, netdev->mtu);
 
@@ -1709,10 +1703,15 @@ qlcnic_xmit_frame(struct sk_buff *skb, struct net_device *netdev)
         /* 4 fragments per cmd des */
         no_of_desc = (frag_count + 3) >> 2;
 
-        if (unlikely(no_of_desc + 2 > qlcnic_tx_avail(tx_ring))) {
+        if (unlikely(qlcnic_tx_avail(tx_ring) <= TX_STOP_THRESH)) {
                 netif_stop_queue(netdev);
-                adapter->stats.xmit_off++;
-                return NETDEV_TX_BUSY;
+                smp_mb();
+                if (qlcnic_tx_avail(tx_ring) > TX_STOP_THRESH)
+                        netif_start_queue(netdev);
+                else {
+                        adapter->stats.xmit_off++;
+                        return NETDEV_TX_BUSY;
+                }
         }
 
         producer = tx_ring->producer;
@@ -2018,14 +2017,12 @@ static int qlcnic_process_cmd_ring(struct qlcnic_adapter *adapter)
                 smp_mb();
 
                 if (netif_queue_stopped(netdev) && netif_carrier_ok(netdev)) {
-                        __netif_tx_lock(tx_ring->txq, smp_processor_id());
                         if (qlcnic_tx_avail(tx_ring) > TX_STOP_THRESH) {
                                 netif_wake_queue(netdev);
-                                adapter->tx_timeo_cnt = 0;
                                 adapter->stats.xmit_on++;
                         }
-                        __netif_tx_unlock(tx_ring->txq);
                 }
+                adapter->tx_timeo_cnt = 0;
         }
         /*
          * If everything is freed up to consumer then check if the ring is full