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[PATCH 3/9] cxgb3: Rework t3_l2t_get to take a dst_entry instead of a neighbour.

From: David Miller <davem@davemloft.net>
Date: 2011-12-03 02:52:21
Subsystem: cxgb3 ethernet driver (cxgb3), infiniband subsystem, networking drivers, scsi subsystem, the rest · Maintainers: Potnuri Bharat Teja, Jason Gunthorpe, Leon Romanovsky, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, "James E.J. Bottomley", "Martin K. Petersen", Linus Torvalds

This way we consolidate the RCU locking down into the place where it
actually matters, and also we can make the code handle
dst_get_neighbour_noref() returning NULL properly.

Signed-off-by: David S. Miller <davem@davemloft.net>
---
 drivers/infiniband/hw/cxgb3/iwch_cm.c              |   15 +---------
 drivers/net/ethernet/chelsio/cxgb3/cxgb3_offload.c |    2 +-
 drivers/net/ethernet/chelsio/cxgb3/l2t.c           |   27 ++++++++++++++-----
 drivers/net/ethernet/chelsio/cxgb3/l2t.h           |    2 +-
 drivers/scsi/cxgbi/cxgb3i/cxgb3i.c                 |    2 +-
 5 files changed, 25 insertions(+), 23 deletions(-)
diff --git a/drivers/infiniband/hw/cxgb3/iwch_cm.c b/drivers/infiniband/hw/cxgb3/iwch_cm.c
index 23686df..740dcc0 100644
--- a/drivers/infiniband/hw/cxgb3/iwch_cm.c
+++ b/drivers/infiniband/hw/cxgb3/iwch_cm.c
@@ -1338,7 +1338,6 @@ static int pass_accept_req(struct t3cdev *tdev, struct sk_buff *skb, void *ctx)
 	struct iwch_ep *child_ep, *parent_ep = ctx;
 	struct cpl_pass_accept_req *req = cplhdr(skb);
 	unsigned int hwtid = GET_TID(req);
-	struct neighbour *neigh;
 	struct dst_entry *dst;
 	struct l2t_entry *l2t;
 	struct rtable *rt;
@@ -1375,10 +1374,7 @@ static int pass_accept_req(struct t3cdev *tdev, struct sk_buff *skb, void *ctx)
 		goto reject;
 	}
 	dst = &rt->dst;
-	rcu_read_lock();
-	neigh = dst_get_neighbour_noref(dst);
-	l2t = t3_l2t_get(tdev, neigh, neigh->dev);
-	rcu_read_unlock();
+	l2t = t3_l2t_get(tdev, dst, NULL);
 	if (!l2t) {
 		printk(KERN_ERR MOD "%s - failed to allocate l2t entry!\n",
 		       __func__);
@@ -1889,7 +1885,6 @@ static int is_loopback_dst(struct iw_cm_id *cm_id)
 int iwch_connect(struct iw_cm_id *cm_id, struct iw_cm_conn_param *conn_param)
 {
 	struct iwch_dev *h = to_iwch_dev(cm_id->device);
-	struct neighbour *neigh;
 	struct iwch_ep *ep;
 	struct rtable *rt;
 	int err = 0;
@@ -1947,13 +1942,7 @@ int iwch_connect(struct iw_cm_id *cm_id, struct iw_cm_conn_param *conn_param)
 		goto fail3;
 	}
 	ep->dst = &rt->dst;
-
-	rcu_read_lock();
-	neigh = dst_get_neighbour_noref(ep->dst);
-
-	/* get a l2t entry */
-	ep->l2t = t3_l2t_get(ep->com.tdev, neigh, neigh->dev);
-	rcu_read_unlock();
+	ep->l2t = t3_l2t_get(ep->com.tdev, ep->dst, NULL);
 	if (!ep->l2t) {
 		printk(KERN_ERR MOD "%s - cannot alloc l2e.\n", __func__);
 		err = -ENOMEM;
diff --git a/drivers/net/ethernet/chelsio/cxgb3/cxgb3_offload.c b/drivers/net/ethernet/chelsio/cxgb3/cxgb3_offload.c
index 6ed9f87..596cfe3 100644
--- a/drivers/net/ethernet/chelsio/cxgb3/cxgb3_offload.c
+++ b/drivers/net/ethernet/chelsio/cxgb3/cxgb3_offload.c
@@ -1132,7 +1132,7 @@ static void cxgb_redirect(struct dst_entry *old, struct dst_entry *new)
 	}
 
 	/* Add new L2T entry */
-	e = t3_l2t_get(tdev, dst_get_neighbour_noref(new), newdev);
+	e = t3_l2t_get(tdev, new, newdev);
 	if (!e) {
 		printk(KERN_ERR "%s: couldn't allocate new l2t entry!\n",
 		       __func__);
diff --git a/drivers/net/ethernet/chelsio/cxgb3/l2t.c b/drivers/net/ethernet/chelsio/cxgb3/l2t.c
index 70fec8b..3fa3c88 100644
--- a/drivers/net/ethernet/chelsio/cxgb3/l2t.c
+++ b/drivers/net/ethernet/chelsio/cxgb3/l2t.c
@@ -298,18 +298,31 @@ static inline void reuse_entry(struct l2t_entry *e, struct neighbour *neigh)
 	spin_unlock(&e->lock);
 }
 
-struct l2t_entry *t3_l2t_get(struct t3cdev *cdev, struct neighbour *neigh,
+struct l2t_entry *t3_l2t_get(struct t3cdev *cdev, struct dst_entry *dst,
 			     struct net_device *dev)
 {
 	struct l2t_entry *e = NULL;
+	struct neighbour *neigh;
+	struct port_info *p;
 	struct l2t_data *d;
 	int hash;
-	u32 addr = *(u32 *) neigh->primary_key;
-	int ifidx = neigh->dev->ifindex;
-	struct port_info *p = netdev_priv(dev);
-	int smt_idx = p->port_id;
+	u32 addr;
+	int ifidx;
+	int smt_idx;
 
 	rcu_read_lock();
+	neigh = dst_get_neighbour_noref(dst);
+	if (!neigh)
+		goto done_rcu;
+
+	addr = *(u32 *) neigh->primary_key;
+	ifidx = neigh->dev->ifindex;
+
+	if (!dev)
+		dev = neigh->dev;
+	p = netdev_priv(dev);
+	smt_idx = p->port_id;
+
 	d = L2DATA(cdev);
 	if (!d)
 		goto done_rcu;
@@ -323,7 +336,7 @@ struct l2t_entry *t3_l2t_get(struct t3cdev *cdev, struct neighbour *neigh,
 			l2t_hold(d, e);
 			if (atomic_read(&e->refcnt) == 1)
 				reuse_entry(e, neigh);
-			goto done;
+			goto done_unlock;
 		}
 
 	/* Need to allocate a new entry */
@@ -344,7 +357,7 @@ struct l2t_entry *t3_l2t_get(struct t3cdev *cdev, struct neighbour *neigh,
 			e->vlan = VLAN_NONE;
 		spin_unlock(&e->lock);
 	}
-done:
+done_unlock:
 	write_unlock_bh(&d->lock);
 done_rcu:
 	rcu_read_unlock();
diff --git a/drivers/net/ethernet/chelsio/cxgb3/l2t.h b/drivers/net/ethernet/chelsio/cxgb3/l2t.h
index c5f5479..c4e8643 100644
--- a/drivers/net/ethernet/chelsio/cxgb3/l2t.h
+++ b/drivers/net/ethernet/chelsio/cxgb3/l2t.h
@@ -109,7 +109,7 @@ static inline void set_arp_failure_handler(struct sk_buff *skb,
 
 void t3_l2e_free(struct l2t_data *d, struct l2t_entry *e);
 void t3_l2t_update(struct t3cdev *dev, struct neighbour *neigh);
-struct l2t_entry *t3_l2t_get(struct t3cdev *cdev, struct neighbour *neigh,
+struct l2t_entry *t3_l2t_get(struct t3cdev *cdev, struct dst_entry *dst,
 			     struct net_device *dev);
 int t3_l2t_send_slow(struct t3cdev *dev, struct sk_buff *skb,
 		     struct l2t_entry *e);
diff --git a/drivers/scsi/cxgbi/cxgb3i/cxgb3i.c b/drivers/scsi/cxgbi/cxgb3i/cxgb3i.c
index 88902d3..36739da 100644
--- a/drivers/scsi/cxgbi/cxgb3i/cxgb3i.c
+++ b/drivers/scsi/cxgbi/cxgb3i/cxgb3i.c
@@ -966,7 +966,7 @@ static int init_act_open(struct cxgbi_sock *csk)
 		csk->saddr.sin_addr.s_addr = chba->ipv4addr;
 
 	csk->rss_qid = 0;
-	csk->l2t = t3_l2t_get(t3dev, dst_get_neighbour_noref(dst), ndev);
+	csk->l2t = t3_l2t_get(t3dev, dst, ndev);
 	if (!csk->l2t) {
 		pr_err("NO l2t available.\n");
 		return -EINVAL;
-- 
1.7.7.3
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