cxgb4: move PTP lock and unlock to caller in Tx path

Check for whether PTP is enabled or not at the caller and perform
locking/unlocking at the caller.

Fixes following sparse warning:
sge.c:1641:26: warning: context imbalance in 'cxgb4_eth_xmit' -
different lock contexts for basic block

Fixes: a4569504 ("cxgb4: time stamping interface for PTP")
Signed-off-by: Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/chelsio/cxgb4/sge.c

@@ -1425,12 +1425,10 @@ static netdev_tx_t cxgb4_eth_xmit(struct sk_buff *skb, struct net_device *dev)
 
 	qidx = skb_get_queue_mapping(skb);
 	if (ptp_enabled) {
-		spin_lock(&adap->ptp_lock);
 		if (!(adap->ptp_tx_skb)) {
 			skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS;
 			adap->ptp_tx_skb = skb_get(skb);
 		} else {
-			spin_unlock(&adap->ptp_lock);
 			goto out_free;
 		}
 		q = &adap->sge.ptptxq;
@@ -1444,11 +1442,8 @@ static netdev_tx_t cxgb4_eth_xmit(struct sk_buff *skb, struct net_device *dev)
 
 #ifdef CONFIG_CHELSIO_T4_FCOE
 	ret = cxgb_fcoe_offload(skb, adap, pi, &cntrl);
-	if (unlikely(ret == -ENOTSUPP)) {
-		if (ptp_enabled)
-			spin_unlock(&adap->ptp_lock);
+	if (unlikely(ret == -EOPNOTSUPP))
 		goto out_free;
-	}
 #endif /* CONFIG_CHELSIO_T4_FCOE */
 
 	chip_ver = CHELSIO_CHIP_VERSION(adap->params.chip);
@@ -1461,8 +1456,6 @@ static netdev_tx_t cxgb4_eth_xmit(struct sk_buff *skb, struct net_device *dev)
 		dev_err(adap->pdev_dev,
 			"%s: Tx ring %u full while queue awake!\n",
 			dev->name, qidx);
-		if (ptp_enabled)
-			spin_unlock(&adap->ptp_lock);
 		return NETDEV_TX_BUSY;
 	}
 
@@ -1481,8 +1474,6 @@ static netdev_tx_t cxgb4_eth_xmit(struct sk_buff *skb, struct net_device *dev)
 	    unlikely(cxgb4_map_skb(adap->pdev_dev, skb, sgl_sdesc->addr) < 0)) {
 		memset(sgl_sdesc->addr, 0, sizeof(sgl_sdesc->addr));
 		q->mapping_err++;
-		if (ptp_enabled)
-			spin_unlock(&adap->ptp_lock);
 		goto out_free;
 	}
 
@@ -1630,8 +1621,6 @@ static netdev_tx_t cxgb4_eth_xmit(struct sk_buff *skb, struct net_device *dev)
 	txq_advance(&q->q, ndesc);
 
 	cxgb4_ring_tx_db(adap, &q->q, ndesc);
-	if (ptp_enabled)
-		spin_unlock(&adap->ptp_lock);
 	return NETDEV_TX_OK;
 
 out_free:
@@ -2377,6 +2366,16 @@ netdev_tx_t t4_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	if (unlikely(qid >= pi->nqsets))
 		return cxgb4_ethofld_xmit(skb, dev);
 
+	if (is_ptp_enabled(skb, dev)) {
+		struct adapter *adap = netdev2adap(dev);
+		netdev_tx_t ret;
+
+		spin_lock(&adap->ptp_lock);
+		ret = cxgb4_eth_xmit(skb, dev);
+		spin_unlock(&adap->ptp_lock);
+		return ret;
+	}
+
 	return cxgb4_eth_xmit(skb, dev);
 }