[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>

diff --git a/drivers/net/chelsio/sge.c b/drivers/net/chelsio/sge.c
index 9911048d821309c5be229799f4549a4b9febcdbe..0ca8d876e16f41903fba9a0530e536f836447f83 100644 (file)
--- 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;
 }
 
 /*