[openib-general] [PATCH] ipoib_multicast/ipoib_mcast_send race

[Michael S. Tsirkin]

Hello, Roland!
Here's another race scenario.

---

Fix the following race scenario:
device is up.
port event or set mcast list triggers ipoib_mcast_stop_thread, 
This cancels the query and waits on mcast "done" completion.
completion is called and "done" is set.
Meanwhile, ipoib_mcast_send arrives and starts a new query,
re-initializing "done".

Signed-off-by: Michael S. Tsirkin <mst at mellanox.co.il>

Index: openib/drivers/infiniband/ulp/ipoib/ipoib.h
===================================================================
--- openib.orig/drivers/infiniband/ulp/ipoib/ipoib.h	2005-12-01 14:53:08.000000000 +0200
+++ openib/drivers/infiniband/ulp/ipoib/ipoib.h	2005-12-07 18:23:55.000000000 +0200
@@ -78,6 +78,7 @@ enum {
 	IPOIB_FLAG_SUBINTERFACE   = 4,
 	IPOIB_MCAST_RUN 	  = 5,
 	IPOIB_STOP_REAPER         = 6,
+	IPOIB_MCAST_STARTED       = 7,
 
 	IPOIB_MAX_BACKOFF_SECONDS = 16,
 
Index: openib/drivers/infiniband/ulp/ipoib/ipoib_multicast.c
===================================================================
--- openib.orig/drivers/infiniband/ulp/ipoib/ipoib_multicast.c	2005-12-07 18:22:12.000000000 +0200
+++ openib/drivers/infiniband/ulp/ipoib/ipoib_multicast.c	2005-12-07 18:29:49.000000000 +0200
@@ -582,6 +582,10 @@ int ipoib_mcast_start_thread(struct net_
 		queue_work(ipoib_workqueue, &priv->mcast_task);
 	up(&mcast_mutex);
 
+	spin_lock_irq(&priv->lock);
+	set_bit(IPOIB_MCAST_STARTED, &priv->flags);
+	spin_unlock_irq(&priv->lock);
+
 	return 0;
 }
 
@@ -592,6 +596,10 @@ int ipoib_mcast_stop_thread(struct net_d
 
 	ipoib_dbg_mcast(priv, "stopping multicast thread\n");
 
+	spin_lock_irq(&priv->lock);
+	clear_bit(IPOIB_MCAST_STARTED, &priv->flags);
+	spin_unlock_irq(&priv->lock);
+
 	down(&mcast_mutex);
 	clear_bit(IPOIB_MCAST_RUN, &priv->flags);
 	cancel_delayed_work(&priv->mcast_task);
@@ -674,6 +682,9 @@ void ipoib_mcast_send(struct net_device 
 	 */
 	spin_lock(&priv->lock);
 
+	if (!test_bit(IPOIB_MCAST_STARTED, &priv->flags))
+		goto unlock;
+
 	mcast = __ipoib_mcast_find(dev, mgid);
 	if (!mcast) {
 		/* Let's create a new send only group now */
@@ -732,6 +743,7 @@ out:
 		ipoib_send(dev, skb, mcast->ah, IB_MULTICAST_QPN);
 	}
 
+unlock:
 	spin_unlock(&priv->lock);
 }
 


-- 
MST