IPoIB: Fix AB-BA deadlock when deleting neighbours
Lockdep points out a circular locking dependency betwwen the ipoib device priv spinlock (priv->lock) and the neighbour table rwlock (ntbl->rwlock). In the normal path, ie neigbour garbage collection task, the neigh table rwlock is taken first and then if the neighbour needs to be deleted, priv->lock is taken. However in some error paths, such as in ipoib_cm_handle_tx_wc(), priv->lock is taken first and then ipoib_neigh_free routine is called which in turn takes the neighbour table ntbl->rwlock. The solution is to get rid the neigh table rwlock completely and use only priv->lock. Signed-off-by: Shlomo Pongratz <shlomop@mellanox.com> Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com> Signed-off-by: Roland Dreier <roland@purestorage.com>
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66172c0993
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b5120a6e11
3 changed files with 27 additions and 46 deletions
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@ -274,7 +274,6 @@ struct ipoib_neigh_hash {
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struct ipoib_neigh_table {
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struct ipoib_neigh_hash __rcu *htbl;
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rwlock_t rwlock;
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atomic_t entries;
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struct completion flushed;
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struct completion deleted;
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@ -546,15 +546,15 @@ static void neigh_add_path(struct sk_buff *skb, u8 *daddr,
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struct ipoib_neigh *neigh;
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unsigned long flags;
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spin_lock_irqsave(&priv->lock, flags);
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neigh = ipoib_neigh_alloc(daddr, dev);
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if (!neigh) {
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spin_unlock_irqrestore(&priv->lock, flags);
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++dev->stats.tx_dropped;
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dev_kfree_skb_any(skb);
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return;
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}
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spin_lock_irqsave(&priv->lock, flags);
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path = __path_find(dev, daddr + 4);
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if (!path) {
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path = path_rec_create(dev, daddr + 4);
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@ -863,10 +863,10 @@ static void __ipoib_reap_neigh(struct ipoib_dev_priv *priv)
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if (test_bit(IPOIB_STOP_NEIGH_GC, &priv->flags))
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return;
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write_lock_bh(&ntbl->rwlock);
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spin_lock_irqsave(&priv->lock, flags);
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htbl = rcu_dereference_protected(ntbl->htbl,
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lockdep_is_held(&ntbl->rwlock));
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lockdep_is_held(&priv->lock));
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if (!htbl)
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goto out_unlock;
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@ -883,16 +883,14 @@ static void __ipoib_reap_neigh(struct ipoib_dev_priv *priv)
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struct ipoib_neigh __rcu **np = &htbl->buckets[i];
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while ((neigh = rcu_dereference_protected(*np,
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lockdep_is_held(&ntbl->rwlock))) != NULL) {
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lockdep_is_held(&priv->lock))) != NULL) {
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/* was the neigh idle for two GC periods */
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if (time_after(neigh_obsolete, neigh->alive)) {
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rcu_assign_pointer(*np,
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rcu_dereference_protected(neigh->hnext,
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lockdep_is_held(&ntbl->rwlock)));
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lockdep_is_held(&priv->lock)));
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/* remove from path/mc list */
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spin_lock_irqsave(&priv->lock, flags);
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list_del(&neigh->list);
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spin_unlock_irqrestore(&priv->lock, flags);
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call_rcu(&neigh->rcu, ipoib_neigh_reclaim);
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} else {
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np = &neigh->hnext;
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@ -902,7 +900,7 @@ static void __ipoib_reap_neigh(struct ipoib_dev_priv *priv)
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}
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out_unlock:
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write_unlock_bh(&ntbl->rwlock);
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spin_unlock_irqrestore(&priv->lock, flags);
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}
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static void ipoib_reap_neigh(struct work_struct *work)
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@ -947,10 +945,8 @@ struct ipoib_neigh *ipoib_neigh_alloc(u8 *daddr,
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struct ipoib_neigh *neigh;
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u32 hash_val;
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write_lock_bh(&ntbl->rwlock);
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htbl = rcu_dereference_protected(ntbl->htbl,
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lockdep_is_held(&ntbl->rwlock));
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lockdep_is_held(&priv->lock));
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if (!htbl) {
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neigh = NULL;
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goto out_unlock;
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@ -961,10 +957,10 @@ struct ipoib_neigh *ipoib_neigh_alloc(u8 *daddr,
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*/
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hash_val = ipoib_addr_hash(htbl, daddr);
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for (neigh = rcu_dereference_protected(htbl->buckets[hash_val],
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lockdep_is_held(&ntbl->rwlock));
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lockdep_is_held(&priv->lock));
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neigh != NULL;
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neigh = rcu_dereference_protected(neigh->hnext,
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lockdep_is_held(&ntbl->rwlock))) {
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lockdep_is_held(&priv->lock))) {
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if (memcmp(daddr, neigh->daddr, INFINIBAND_ALEN) == 0) {
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/* found, take one ref on behalf of the caller */
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if (!atomic_inc_not_zero(&neigh->refcnt)) {
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@ -987,12 +983,11 @@ struct ipoib_neigh *ipoib_neigh_alloc(u8 *daddr,
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/* put in hash */
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rcu_assign_pointer(neigh->hnext,
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rcu_dereference_protected(htbl->buckets[hash_val],
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lockdep_is_held(&ntbl->rwlock)));
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lockdep_is_held(&priv->lock)));
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rcu_assign_pointer(htbl->buckets[hash_val], neigh);
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atomic_inc(&ntbl->entries);
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out_unlock:
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write_unlock_bh(&ntbl->rwlock);
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return neigh;
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}
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@ -1040,35 +1035,29 @@ void ipoib_neigh_free(struct ipoib_neigh *neigh)
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struct ipoib_neigh *n;
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u32 hash_val;
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write_lock_bh(&ntbl->rwlock);
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htbl = rcu_dereference_protected(ntbl->htbl,
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lockdep_is_held(&ntbl->rwlock));
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lockdep_is_held(&priv->lock));
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if (!htbl)
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goto out_unlock;
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return;
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hash_val = ipoib_addr_hash(htbl, neigh->daddr);
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np = &htbl->buckets[hash_val];
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for (n = rcu_dereference_protected(*np,
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lockdep_is_held(&ntbl->rwlock));
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lockdep_is_held(&priv->lock));
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n != NULL;
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n = rcu_dereference_protected(*np,
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lockdep_is_held(&ntbl->rwlock))) {
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lockdep_is_held(&priv->lock))) {
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if (n == neigh) {
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/* found */
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rcu_assign_pointer(*np,
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rcu_dereference_protected(neigh->hnext,
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lockdep_is_held(&ntbl->rwlock)));
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lockdep_is_held(&priv->lock)));
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call_rcu(&neigh->rcu, ipoib_neigh_reclaim);
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goto out_unlock;
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return;
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} else {
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np = &n->hnext;
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}
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}
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out_unlock:
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write_unlock_bh(&ntbl->rwlock);
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}
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static int ipoib_neigh_hash_init(struct ipoib_dev_priv *priv)
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@ -1080,7 +1069,6 @@ static int ipoib_neigh_hash_init(struct ipoib_dev_priv *priv)
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clear_bit(IPOIB_NEIGH_TBL_FLUSH, &priv->flags);
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ntbl->htbl = NULL;
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rwlock_init(&ntbl->rwlock);
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htbl = kzalloc(sizeof(*htbl), GFP_KERNEL);
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if (!htbl)
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return -ENOMEM;
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@ -1128,10 +1116,10 @@ void ipoib_del_neighs_by_gid(struct net_device *dev, u8 *gid)
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int i;
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/* remove all neigh connected to a given path or mcast */
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write_lock_bh(&ntbl->rwlock);
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spin_lock_irqsave(&priv->lock, flags);
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htbl = rcu_dereference_protected(ntbl->htbl,
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lockdep_is_held(&ntbl->rwlock));
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lockdep_is_held(&priv->lock));
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if (!htbl)
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goto out_unlock;
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@ -1141,16 +1129,14 @@ void ipoib_del_neighs_by_gid(struct net_device *dev, u8 *gid)
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struct ipoib_neigh __rcu **np = &htbl->buckets[i];
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while ((neigh = rcu_dereference_protected(*np,
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lockdep_is_held(&ntbl->rwlock))) != NULL) {
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lockdep_is_held(&priv->lock))) != NULL) {
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/* delete neighs belong to this parent */
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if (!memcmp(gid, neigh->daddr + 4, sizeof (union ib_gid))) {
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rcu_assign_pointer(*np,
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rcu_dereference_protected(neigh->hnext,
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lockdep_is_held(&ntbl->rwlock)));
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lockdep_is_held(&priv->lock)));
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/* remove from parent list */
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spin_lock_irqsave(&priv->lock, flags);
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list_del(&neigh->list);
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spin_unlock_irqrestore(&priv->lock, flags);
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call_rcu(&neigh->rcu, ipoib_neigh_reclaim);
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} else {
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np = &neigh->hnext;
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@ -1159,7 +1145,7 @@ void ipoib_del_neighs_by_gid(struct net_device *dev, u8 *gid)
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}
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}
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out_unlock:
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write_unlock_bh(&ntbl->rwlock);
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spin_unlock_irqrestore(&priv->lock, flags);
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}
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static void ipoib_flush_neighs(struct ipoib_dev_priv *priv)
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@ -1171,10 +1157,10 @@ static void ipoib_flush_neighs(struct ipoib_dev_priv *priv)
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init_completion(&priv->ntbl.flushed);
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write_lock_bh(&ntbl->rwlock);
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spin_lock_irqsave(&priv->lock, flags);
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htbl = rcu_dereference_protected(ntbl->htbl,
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lockdep_is_held(&ntbl->rwlock));
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lockdep_is_held(&priv->lock));
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if (!htbl)
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goto out_unlock;
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@ -1187,14 +1173,12 @@ static void ipoib_flush_neighs(struct ipoib_dev_priv *priv)
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struct ipoib_neigh __rcu **np = &htbl->buckets[i];
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while ((neigh = rcu_dereference_protected(*np,
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lockdep_is_held(&ntbl->rwlock))) != NULL) {
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lockdep_is_held(&priv->lock))) != NULL) {
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rcu_assign_pointer(*np,
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rcu_dereference_protected(neigh->hnext,
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lockdep_is_held(&ntbl->rwlock)));
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lockdep_is_held(&priv->lock)));
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/* remove from path/mc list */
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spin_lock_irqsave(&priv->lock, flags);
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list_del(&neigh->list);
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spin_unlock_irqrestore(&priv->lock, flags);
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call_rcu(&neigh->rcu, ipoib_neigh_reclaim);
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}
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}
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@ -1204,7 +1188,7 @@ static void ipoib_flush_neighs(struct ipoib_dev_priv *priv)
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call_rcu(&htbl->rcu, neigh_hash_free_rcu);
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out_unlock:
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write_unlock_bh(&ntbl->rwlock);
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spin_unlock_irqrestore(&priv->lock, flags);
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if (wait_flushed)
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wait_for_completion(&priv->ntbl.flushed);
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}
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@ -707,9 +707,7 @@ void ipoib_mcast_send(struct net_device *dev, u8 *daddr, struct sk_buff *skb)
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neigh = ipoib_neigh_get(dev, daddr);
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spin_lock_irqsave(&priv->lock, flags);
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if (!neigh) {
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spin_unlock_irqrestore(&priv->lock, flags);
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neigh = ipoib_neigh_alloc(daddr, dev);
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spin_lock_irqsave(&priv->lock, flags);
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if (neigh) {
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kref_get(&mcast->ah->ref);
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neigh->ah = mcast->ah;
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