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, 22 insertions, 8 deletions

diff --git a/drivers/infiniband/ulp/ipoib/ipoib_ib.c b/drivers/infiniband/ulp/ipoib/ipoib_ib.c
index 66cafa20c24..0e748aeeae9 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib_ib.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_ib.c
@@ -468,21 +468,22 @@ void ipoib_ib_completion(struct ib_cq *cq, void *dev_ptr)
 static void drain_tx_cq(struct net_device *dev)
 {
 	struct ipoib_dev_priv *priv = netdev_priv(dev);
-	unsigned long flags;
 
-	spin_lock_irqsave(&priv->tx_lock, flags);
+	netif_tx_lock(dev);
 	while (poll_tx(priv))
 		; /* nothing */
 
 	if (netif_queue_stopped(dev))
 		mod_timer(&priv->poll_timer, jiffies + 1);
 
-	spin_unlock_irqrestore(&priv->tx_lock, flags);
+	netif_tx_unlock(dev);
 }
 
 void ipoib_send_comp_handler(struct ib_cq *cq, void *dev_ptr)
 {
-	drain_tx_cq((struct net_device *)dev_ptr);
+	struct ipoib_dev_priv *priv = netdev_priv(dev_ptr);
+
+	mod_timer(&priv->poll_timer, jiffies);
 }
 
 static inline int post_send(struct ipoib_dev_priv *priv,
@@ -614,17 +615,20 @@ static void __ipoib_reap_ah(struct net_device *dev)
 	struct ipoib_dev_priv *priv = netdev_priv(dev);
 	struct ipoib_ah *ah, *tah;
 	LIST_HEAD(remove_list);
+	unsigned long flags;
+
+	netif_tx_lock_bh(dev);
+	spin_lock_irqsave(&priv->lock, flags);
 
-	spin_lock_irq(&priv->tx_lock);
-	spin_lock(&priv->lock);
 	list_for_each_entry_safe(ah, tah, &priv->dead_ahs, list)
 		if ((int) priv->tx_tail - (int) ah->last_send >= 0) {
 			list_del(&ah->list);
 			ib_destroy_ah(ah->ah);
 			kfree(ah);
 		}
-	spin_unlock(&priv->lock);
-	spin_unlock_irq(&priv->tx_lock);
+
+	spin_unlock_irqrestore(&priv->lock, flags);
+	netif_tx_unlock_bh(dev);
 }
 
 void ipoib_reap_ah(struct work_struct *work)
@@ -761,6 +765,14 @@ void ipoib_drain_cq(struct net_device *dev)
 {
 	struct ipoib_dev_priv *priv = netdev_priv(dev);
 	int i, n;
+
+	/*
+	 * We call completion handling routines that expect to be
+	 * called from the BH-disabled NAPI poll context, so disable
+	 * BHs here too.
+	 */
+	local_bh_disable();
+
 	do {
 		n = ib_poll_cq(priv->recv_cq, IPOIB_NUM_WC, priv->ibwc);
 		for (i = 0; i < n; ++i) {
@@ -784,6 +796,8 @@ void ipoib_drain_cq(struct net_device *dev)
 
 	while (poll_tx(priv))
 		; /* nothing */
+
+	local_bh_enable();
 }
 
 int ipoib_ib_dev_stop(struct net_device *dev, int flush)