IPoIB: Use netif_tx_lock() and get rid of private tx_lock, LLTX

Currently, IPoIB is an LLTX driver that uses its own IRQ-disabling
tx_lock.  Not only do we want to get rid of LLTX, this actually causes
problems because of the skb_orphan() done with this tx_lock held: some
skb destructors expect to be run with interrupts enabled.

The simplest fix for this is to get rid of the driver-private tx_lock
and stop using LLTX.  We kill off priv->tx_lock and use
netif_tx_lock[_bh]() instead; the patch to do this is a tiny bit
tricky because we need to update places that take priv->lock inside
the tx_lock to disable IRQs, rather than relying on tx_lock having
already disabled IRQs.

Also, there are a couple of places where we need to disable BHs to
make sure we have a consistent context to call netif_tx_lock() (since
we no longer can use _irqsave() variants), and we also have to change
ipoib_send_comp_handler() to call drain_tx_cq() through a timer rather
than directly, because ipoib_send_comp_handler() runs in interrupt
context and drain_tx_cq() must run in BH context so it can call
netif_tx_lock().

Signed-off-by: Roland Dreier <rolandd@cisco.com>

1 files changed, 28 insertions, 40 deletions

diff --git a/drivers/infiniband/ulp/ipoib/ipoib_main.c b/drivers/infiniband/ulp/ipoib/ipoib_main.c
index e9ca3cb57d5..c0ee514396d 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib_main.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_main.c
@@ -373,9 +373,10 @@ void ipoib_flush_paths(struct net_device *dev)
         struct ipoib_dev_priv *priv = netdev_priv(dev);
         struct ipoib_path *path, *tp;
         LIST_HEAD(remove_list);
+        unsigned long flags;
 
-        spin_lock_irq(&priv->tx_lock);
-        spin_lock(&priv->lock);
+        netif_tx_lock_bh(dev);
+        spin_lock_irqsave(&priv->lock, flags);
 
         list_splice_init(&priv->path_list, &remove_list);
 
@@ -385,15 +386,16 @@ void ipoib_flush_paths(struct net_device *dev)
         list_for_each_entry_safe(path, tp, &remove_list, list) {
                 if (path->query)
                         ib_sa_cancel_query(path->query_id, path->query);
-                spin_unlock(&priv->lock);
-                spin_unlock_irq(&priv->tx_lock);
+                spin_unlock_irqrestore(&priv->lock, flags);
+                netif_tx_unlock_bh(dev);
                 wait_for_completion(&path->done);
                 path_free(dev, path);
-                spin_lock_irq(&priv->tx_lock);
-                spin_lock(&priv->lock);
+                netif_tx_lock_bh(dev);
+                spin_lock_irqsave(&priv->lock, flags);
         }
-        spin_unlock(&priv->lock);
-        spin_unlock_irq(&priv->tx_lock);
+
+        spin_unlock_irqrestore(&priv->lock, flags);
+        netif_tx_unlock_bh(dev);
 }
 
 static void path_rec_completion(int status,
@@ -555,6 +557,7 @@ static void neigh_add_path(struct sk_buff *skb, struct net_device *dev)
         struct ipoib_dev_priv *priv = netdev_priv(dev);
         struct ipoib_path *path;
         struct ipoib_neigh *neigh;
+        unsigned long flags;
 
         neigh = ipoib_neigh_alloc(skb->dst->neighbour, skb->dev);
         if (!neigh) {
@@ -563,11 +566,7 @@ static void neigh_add_path(struct sk_buff *skb, struct net_device *dev)
                 return;
         }
 
-        /*
-         * We can only be called from ipoib_start_xmit, so we're
-         * inside tx_lock -- no need to save/restore flags.
-         */
-        spin_lock(&priv->lock);
+        spin_lock_irqsave(&priv->lock, flags);
 
         path = __path_find(dev, skb->dst->neighbour->ha + 4);
         if (!path) {
@@ -614,7 +613,7 @@ static void neigh_add_path(struct sk_buff *skb, struct net_device *dev)
                 __skb_queue_tail(&neigh->queue, skb);
         }
 
-        spin_unlock(&priv->lock);
+        spin_unlock_irqrestore(&priv->lock, flags);
         return;
 
 err_list:
@@ -626,7 +625,7 @@ err_drop:
         ++dev->stats.tx_dropped;
         dev_kfree_skb_any(skb);
 
-        spin_unlock(&priv->lock);
+        spin_unlock_irqrestore(&priv->lock, flags);
 }
 
 static void ipoib_path_lookup(struct sk_buff *skb, struct net_device *dev)
@@ -650,12 +649,9 @@ static void unicast_arp_send(struct sk_buff *skb, struct net_device *dev,
 {
         struct ipoib_dev_priv *priv = netdev_priv(dev);
         struct ipoib_path *path;
+        unsigned long flags;
 
-        /*
-         * We can only be called from ipoib_start_xmit, so we're
-         * inside tx_lock -- no need to save/restore flags.
-         */
-        spin_lock(&priv->lock);
+        spin_lock_irqsave(&priv->lock, flags);
 
         path = __path_find(dev, phdr->hwaddr + 4);
         if (!path || !path->valid) {
@@ -667,7 +663,7 @@ static void unicast_arp_send(struct sk_buff *skb, struct net_device *dev,
                         __skb_queue_tail(&path->queue, skb);
 
                         if (path_rec_start(dev, path)) {
-                                spin_unlock(&priv->lock);
+                                spin_unlock_irqrestore(&priv->lock, flags);
                                 path_free(dev, path);
                                 return;
                         } else
@@ -677,7 +673,7 @@ static void unicast_arp_send(struct sk_buff *skb, struct net_device *dev,
                         dev_kfree_skb_any(skb);
                 }
 
-                spin_unlock(&priv->lock);
+                spin_unlock_irqrestore(&priv->lock, flags);
                 return;
         }
 
@@ -696,7 +692,7 @@ static void unicast_arp_send(struct sk_buff *skb, struct net_device *dev,
                 dev_kfree_skb_any(skb);
         }
 
-        spin_unlock(&priv->lock);
+        spin_unlock_irqrestore(&priv->lock, flags);
 }
 
 static int ipoib_start_xmit(struct sk_buff *skb, struct net_device *dev)
@@ -705,13 +701,10 @@ static int ipoib_start_xmit(struct sk_buff *skb, struct net_device *dev)
         struct ipoib_neigh *neigh;
         unsigned long flags;
 
-        if (unlikely(!spin_trylock_irqsave(&priv->tx_lock, flags)))
-                return NETDEV_TX_LOCKED;
-
         if (likely(skb->dst && skb->dst->neighbour)) {
                 if (unlikely(!*to_ipoib_neigh(skb->dst->neighbour))) {
                         ipoib_path_lookup(skb, dev);
-                        goto out;
+                        return NETDEV_TX_OK;
                 }
 
                 neigh = *to_ipoib_neigh(skb->dst->neighbour);
@@ -721,7 +714,7 @@ static int ipoib_start_xmit(struct sk_buff *skb, struct net_device *dev)
                                             skb->dst->neighbour->ha + 4,
                                             sizeof(union ib_gid))) ||
                                          (neigh->dev != dev))) {
-                                spin_lock(&priv->lock);
+                                spin_lock_irqsave(&priv->lock, flags);
                                 /*
                                  * It's safe to call ipoib_put_ah() inside
                                  * priv->lock here, because we know that
@@ -732,25 +725,25 @@ static int ipoib_start_xmit(struct sk_buff *skb, struct net_device *dev)
                                 ipoib_put_ah(neigh->ah);
                                 list_del(&neigh->list);
                                 ipoib_neigh_free(dev, neigh);
-                                spin_unlock(&priv->lock);
+                                spin_unlock_irqrestore(&priv->lock, flags);
                                 ipoib_path_lookup(skb, dev);
-                                goto out;
+                                return NETDEV_TX_OK;
                         }
 
                 if (ipoib_cm_get(neigh)) {
                         if (ipoib_cm_up(neigh)) {
                                 ipoib_cm_send(dev, skb, ipoib_cm_get(neigh));
-                                goto out;
+                                return NETDEV_TX_OK;
                         }
                 } else if (neigh->ah) {
                         ipoib_send(dev, skb, neigh->ah, IPOIB_QPN(skb->dst->neighbour->ha));
-                        goto out;
+                        return NETDEV_TX_OK;
                 }
 
                 if (skb_queue_len(&neigh->queue) < IPOIB_MAX_PATH_REC_QUEUE) {
-                        spin_lock(&priv->lock);
+                        spin_lock_irqsave(&priv->lock, flags);
                         __skb_queue_tail(&neigh->queue, skb);
-                        spin_unlock(&priv->lock);
+                        spin_unlock_irqrestore(&priv->lock, flags);
                 } else {
                         ++dev->stats.tx_dropped;
                         dev_kfree_skb_any(skb);
@@ -779,16 +772,13 @@ static int ipoib_start_xmit(struct sk_buff *skb, struct net_device *dev)
                                            IPOIB_GID_RAW_ARG(phdr->hwaddr + 4));
                                 dev_kfree_skb_any(skb);
                                 ++dev->stats.tx_dropped;
-                                goto out;
+                                return NETDEV_TX_OK;
                         }
 
                         unicast_arp_send(skb, dev, phdr);
                 }
         }
 
-out:
-        spin_unlock_irqrestore(&priv->tx_lock, flags);
-
         return NETDEV_TX_OK;
 }
 
@@ -1052,7 +1042,6 @@ static void ipoib_setup(struct net_device *dev)
         dev->type                = ARPHRD_INFINIBAND;
         dev->tx_queue_len        = ipoib_sendq_size * 2;
         dev->features            = (NETIF_F_VLAN_CHALLENGED     |
-                                    NETIF_F_LLTX                |
                                     NETIF_F_HIGHDMA);
 
         memcpy(dev->broadcast, ipv4_bcast_addr, INFINIBAND_ALEN);
@@ -1064,7 +1053,6 @@ static void ipoib_setup(struct net_device *dev)
         ipoib_lro_setup(priv);
 
         spin_lock_init(&priv->lock);
-        spin_lock_init(&priv->tx_lock);
 
         mutex_init(&priv->vlan_mutex);