[PATCH] chelesio: transmit locking (plus bug fix).

If transmit lock is contended on, then push return code back
and retry at higher level.

Bugfix: If buffer is reallocated because of lack of headroom
and the send is blocked, then drop packet. This is necessary
because caller would end up requeuing a freed skb.

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 15 insertions, 4 deletions

diff --git a/drivers/net/chelsio/sge.c b/drivers/net/chelsio/sge.c
index 9911048d821..0ca8d876e16 100644
--- a/drivers/net/chelsio/sge.c
+++ b/drivers/net/chelsio/sge.c
@@ -1778,7 +1778,9 @@ static int t1_sge_tx(struct sk_buff *skb, struct adapter *adapter,
         struct cmdQ *q = &sge->cmdQ[qid];
         unsigned int credits, pidx, genbit, count, use_sched_skb = 0;
 
-        spin_lock(&q->lock);
+        if (!spin_trylock(&q->lock))
+                return NETDEV_TX_LOCKED;
+
         reclaim_completed_tx(sge, q);
 
         pidx = q->pidx;
@@ -1887,6 +1889,8 @@ int t1_start_xmit(struct sk_buff *skb, struct net_device *dev)
         struct sge *sge = adapter->sge;
         struct sge_port_stats *st = per_cpu_ptr(sge->port_stats[dev->if_port], smp_processor_id());
         struct cpl_tx_pkt *cpl;
+        struct sk_buff *orig_skb = skb;
+        int ret;
 
         if (skb->protocol == htons(ETH_P_CPL5))
                 goto send;
@@ -1930,8 +1934,6 @@ int t1_start_xmit(struct sk_buff *skb, struct net_device *dev)
                  * Complain when this happens but try to fix things up.
                  */
                 if (unlikely(skb_headroom(skb) < dev->hard_header_len - ETH_HLEN)) {
-                        struct sk_buff *orig_skb = skb;
-
                         pr_debug("%s: headroom %d header_len %d\n", dev->name,
                                  skb_headroom(skb), dev->hard_header_len);
 
@@ -1991,7 +1993,16 @@ int t1_start_xmit(struct sk_buff *skb, struct net_device *dev)
 send:
         st->tx_packets++;
         dev->trans_start = jiffies;
-        return t1_sge_tx(skb, adapter, 0, dev);
+        ret = t1_sge_tx(skb, adapter, 0, dev);
+
+        /* If transmit busy, and we reallocated skb's due to headroom limit,
+         * then silently discard to avoid leak.
+         */
+        if (unlikely(ret != NETDEV_TX_OK && skb != orig_skb)) {
+                dev_kfree_skb_any(skb);
+                ret = NETDEV_TX_OK;
+        }
+        return ret;
 }
 
 /*