RDMA/ipoib: Update paths on CLIENT_REREG/SM_CHANGE events

We do a light flush on CLIENT_REREG and SM_CHANGE events.  This goes
through and marks paths invalid. But we weren't always checking for this
validity when we needed to, and so we could keep using a path marked
invalid.  What's more, once we establish a path with a valid ah, we put
a pointer to the ah in the neigh struct directly, so even if we mark the
path as invalid, as long as the neigh has a direct pointer to the ah, it
keeps using the old, outdated ah.

To fix this we do several things.

1) Put the valid flag in the ah instead of the path struct, so when we
put the ah pointer directly in the neigh struct, we can easily check the
validity of the ah on send events.
2) Check the neigh->ah and neigh->ah->valid elements in the needed
places, and if we have an ah, but it's invalid, then invoke a refresh of
the ah.
3) Fix the various places that check for path, but didn't check for
path->valid (now path->ah && path->ah->valid).

Reported-by: Evgenii Smirnov <evgenii.smirnov@profitbricks.com>
Fixes: ee1e2c8 ("IPoIB: Refresh paths instead of flushing them on SM change events")
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/ulp/ipoib/ipoib.h

@@ -415,6 +415,7 @@ struct ipoib_ah {
 	struct list_head   list;
 	struct kref	   ref;
 	unsigned	   last_send;
+	int  		   valid;
 };
 
 struct ipoib_path {
@@ -431,7 +432,6 @@ struct ipoib_path {
 
 	struct rb_node	      rb_node;
 	struct list_head      list;
-	int  		      valid;
 };
 
 struct ipoib_neigh {

drivers/infiniband/ulp/ipoib/ipoib_main.c

@@ -697,7 +697,8 @@ void ipoib_mark_paths_invalid(struct net_device *dev)
 		ipoib_dbg(priv, "mark path LID 0x%08x GID %pI6 invalid\n",
 			  be32_to_cpu(sa_path_get_dlid(&path->pathrec)),
 			  path->pathrec.dgid.raw);
-		path->valid =  0;
+		if (path->ah)
+			path->ah->valid = 0;
 	}
 
 	spin_unlock_irq(&priv->lock);
@@ -833,7 +834,7 @@ static void path_rec_completion(int status,
 			while ((skb = __skb_dequeue(&neigh->queue)))
 				__skb_queue_tail(&skqueue, skb);
 		}
-		path->valid = 1;
+		path->ah->valid = 1;
 	}
 
 	path->query = NULL;
@@ -926,6 +927,24 @@ static int path_rec_start(struct net_device *dev,
 	return 0;
 }
 
+static void neigh_refresh_path(struct ipoib_neigh *neigh, u8 *daddr,
+			       struct net_device *dev)
+{
+	struct ipoib_dev_priv *priv = ipoib_priv(dev);
+	struct ipoib_path *path;
+	unsigned long flags;
+
+	spin_lock_irqsave(&priv->lock, flags);
+
+	path = __path_find(dev, daddr + 4);
+	if (!path)
+		goto out;
+	if (!path->query)
+		path_rec_start(dev, path);
+out:
+	spin_unlock_irqrestore(&priv->lock, flags);
+}
+
 static struct ipoib_neigh *neigh_add_path(struct sk_buff *skb, u8 *daddr,
 					  struct net_device *dev)
 {
@@ -963,7 +982,7 @@ static struct ipoib_neigh *neigh_add_path(struct sk_buff *skb, u8 *daddr,
 
 	list_add_tail(&neigh->list, &path->neigh_list);
 
-	if (path->ah) {
+	if (path->ah && path->ah->valid) {
 		kref_get(&path->ah->ref);
 		neigh->ah = path->ah;
 
@@ -1034,7 +1053,7 @@ static void unicast_arp_send(struct sk_buff *skb, struct net_device *dev,
 		goto drop_and_unlock;
 
 	path = __path_find(dev, phdr->hwaddr + 4);
-	if (!path || !path->valid) {
+	if (!path || !path->ah || !path->ah->valid) {
 		int new_path = 0;
 
 		if (!path) {
@@ -1069,7 +1088,7 @@ static void unicast_arp_send(struct sk_buff *skb, struct net_device *dev,
 		return;
 	}
 
-	if (path->ah) {
+	if (path->ah && path->ah->valid) {
 		ipoib_dbg(priv, "Send unicast ARP to %08x\n",
 			  be32_to_cpu(sa_path_get_dlid(&path->pathrec)));
 
@@ -1161,10 +1180,12 @@ static netdev_tx_t ipoib_start_xmit(struct sk_buff *skb, struct net_device *dev)
 			ipoib_cm_send(dev, skb, ipoib_cm_get(neigh));
 			goto unref;
 		}
-	} else if (neigh->ah) {
+	} else if (neigh->ah && neigh->ah->valid) {
 		neigh->ah->last_send = rn->send(dev, skb, neigh->ah->ah,
 						IPOIB_QPN(phdr->hwaddr));
 		goto unref;
+	} else if (neigh->ah) {
+		neigh_refresh_path(neigh, phdr->hwaddr, dev);
 	}
 
 	if (skb_queue_len(&neigh->queue) < IPOIB_MAX_PATH_REC_QUEUE) {