2 files changed, 238 insertions, 128 deletions

diff --git a/drivers/infiniband/ulp/ipoib/ipoib.h b/drivers/infiniband/ulp/ipoib/ipoib.h
index 9ef432ae72e8..c79dcd5ee8ad 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib.h
+++ b/drivers/infiniband/ulp/ipoib/ipoib.h
@@ -98,9 +98,15 @@ enum {
 
 	IPOIB_MCAST_FLAG_FOUND	  = 0,	/* used in set_multicast_list */
 	IPOIB_MCAST_FLAG_SENDONLY = 1,
-	IPOIB_MCAST_FLAG_BUSY	  = 2,	/* joining or already joined */
+	/*
+	 * For IPOIB_MCAST_FLAG_BUSY
+	 * When set, in flight join and mcast->mc is unreliable
+	 * When clear and mcast->mc IS_ERR_OR_NULL, need to restart or
+	 *   haven't started yet
+	 * When clear and mcast->mc is valid pointer, join was successful
+	 */
+	IPOIB_MCAST_FLAG_BUSY	  = 2,
 	IPOIB_MCAST_FLAG_ATTACHED = 3,
-	IPOIB_MCAST_JOIN_STARTED  = 4,
 
 	MAX_SEND_CQE		  = 16,
 	IPOIB_CM_COPYBREAK	  = 256,
@@ -148,6 +154,7 @@ struct ipoib_mcast {
 
 	unsigned long created;
 	unsigned long backoff;
+	unsigned long delay_until;
 
 	unsigned long flags;
 	unsigned char logcount;
diff --git a/drivers/infiniband/ulp/ipoib/ipoib_multicast.c b/drivers/infiniband/ulp/ipoib/ipoib_multicast.c
index bb1b69904f96..277e7ac7c4db 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib_multicast.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_multicast.c
@@ -66,6 +66,48 @@ struct ipoib_mcast_iter {
 	unsigned int       send_only;
 };
 
+/*
+ * This should be called with the mcast_mutex held
+ */
+static void __ipoib_mcast_schedule_join_thread(struct ipoib_dev_priv *priv,
+					       struct ipoib_mcast *mcast,
+					       bool delay)
+{
+	if (!test_bit(IPOIB_MCAST_RUN, &priv->flags))
+		return;
+
+	/*
+	 * We will be scheduling *something*, so cancel whatever is
+	 * currently scheduled first
+	 */
+	cancel_delayed_work(&priv->mcast_task);
+	if (mcast && delay) {
+		/*
+		 * We had a failure and want to schedule a retry later
+		 */
+		mcast->backoff *= 2;
+		if (mcast->backoff > IPOIB_MAX_BACKOFF_SECONDS)
+			mcast->backoff = IPOIB_MAX_BACKOFF_SECONDS;
+		mcast->delay_until = jiffies + (mcast->backoff * HZ);
+		/*
+		 * Mark this mcast for its delay, but restart the
+		 * task immediately.  The join task will make sure to
+		 * clear out all entries without delays, and then
+		 * schedule itself to run again when the earliest
+		 * delay expires
+		 */
+		queue_delayed_work(priv->wq, &priv->mcast_task, 0);
+	} else if (delay) {
+		/*
+		 * Special case of retrying after a failure to
+		 * allocate the broadcast multicast group, wait
+		 * 1 second and try again
+		 */
+		queue_delayed_work(priv->wq, &priv->mcast_task, HZ);
+	} else
+		queue_delayed_work(priv->wq, &priv->mcast_task, 0);
+}
+
 static void ipoib_mcast_free(struct ipoib_mcast *mcast)
 {
 	struct net_device *dev = mcast->dev;
@@ -103,6 +145,7 @@ static struct ipoib_mcast *ipoib_mcast_alloc(struct net_device *dev,
 
 	mcast->dev = dev;
 	mcast->created = jiffies;
+	mcast->delay_until = jiffies;
 	mcast->backoff = 1;
 
 	INIT_LIST_HEAD(&mcast->list);
@@ -270,17 +313,31 @@ ipoib_mcast_sendonly_join_complete(int status,
 {
 	struct ipoib_mcast *mcast = multicast->context;
 	struct net_device *dev = mcast->dev;
+	struct ipoib_dev_priv *priv = netdev_priv(dev);
+
+	/*
+	 * We have to take the mutex to force mcast_sendonly_join to
+	 * return from ib_sa_multicast_join and set mcast->mc to a
+	 * valid value.  Otherwise we were racing with ourselves in
+	 * that we might fail here, but get a valid return from
+	 * ib_sa_multicast_join after we had cleared mcast->mc here,
+	 * resulting in mis-matched joins and leaves and a deadlock
+	 */
+	mutex_lock(&mcast_mutex);
 
 	/* We trap for port events ourselves. */
-	if (status == -ENETRESET)
-		return 0;
+	if (status == -ENETRESET) {
+		status = 0;
+		goto out;
+	}
 
 	if (!status)
 		status = ipoib_mcast_join_finish(mcast, &multicast->rec);
 
 	if (status) {
 		if (mcast->logcount++ < 20)
-			ipoib_dbg_mcast(netdev_priv(dev), "multicast join failed for %pI6, status %d\n",
+			ipoib_dbg_mcast(netdev_priv(dev), "sendonly multicast "
+					"join failed for %pI6, status %d\n",
 					mcast->mcmember.mgid.raw, status);
 
 		/* Flush out any queued packets */
@@ -290,11 +347,18 @@ ipoib_mcast_sendonly_join_complete(int status,
 			dev_kfree_skb_any(skb_dequeue(&mcast->pkt_queue));
 		}
 		netif_tx_unlock_bh(dev);
-
-		/* Clear the busy flag so we try again */
-		status = test_and_clear_bit(IPOIB_MCAST_FLAG_BUSY,
-					    &mcast->flags);
+		__ipoib_mcast_schedule_join_thread(priv, mcast, 1);
+	} else {
+		mcast->backoff = 1;
+		mcast->delay_until = jiffies;
+		__ipoib_mcast_schedule_join_thread(priv, NULL, 0);
 	}
+out:
+	clear_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags);
+	if (status)
+		mcast->mc = NULL;
+	complete(&mcast->done);
+	mutex_unlock(&mcast_mutex);
 	return status;
 }
 
@@ -312,19 +376,18 @@ static int ipoib_mcast_sendonly_join(struct ipoib_mcast *mcast)
 	int ret = 0;
 
 	if (!test_bit(IPOIB_FLAG_OPER_UP, &priv->flags)) {
-		ipoib_dbg_mcast(priv, "device shutting down, no multicast joins\n");
+		ipoib_dbg_mcast(priv, "device shutting down, no sendonly "
+				"multicast joins\n");
+		clear_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags);
+		complete(&mcast->done);
 		return -ENODEV;
 	}
 
-	if (test_and_set_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags)) {
-		ipoib_dbg_mcast(priv, "multicast entry busy, skipping\n");
-		return -EBUSY;
-	}
-
 	rec.mgid     = mcast->mcmember.mgid;
 	rec.port_gid = priv->local_gid;
 	rec.pkey     = cpu_to_be16(priv->pkey);
 
+	mutex_lock(&mcast_mutex);
 	mcast->mc = ib_sa_join_multicast(&ipoib_sa_client, priv->ca,
 					 priv->port, &rec,
 					 IB_SA_MCMEMBER_REC_MGID	|
@@ -337,12 +400,14 @@ static int ipoib_mcast_sendonly_join(struct ipoib_mcast *mcast)
 	if (IS_ERR(mcast->mc)) {
 		ret = PTR_ERR(mcast->mc);
 		clear_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags);
-		ipoib_warn(priv, "ib_sa_join_multicast failed (ret = %d)\n",
-			   ret);
+		ipoib_warn(priv, "ib_sa_join_multicast for sendonly join "
+			   "failed (ret = %d)\n", ret);
+		complete(&mcast->done);
 	} else {
-		ipoib_dbg_mcast(priv, "no multicast record for %pI6, starting join\n",
-				mcast->mcmember.mgid.raw);
+		ipoib_dbg_mcast(priv, "no multicast record for %pI6, starting "
+				"sendonly join\n", mcast->mcmember.mgid.raw);
 	}
+	mutex_unlock(&mcast_mutex);
 
 	return ret;
 }
@@ -390,6 +455,16 @@ static int ipoib_mcast_join_complete(int status,
 	ipoib_dbg_mcast(priv, "join completion for %pI6 (status %d)\n",
 			mcast->mcmember.mgid.raw, status);
 
+	/*
+	 * We have to take the mutex to force mcast_join to
+	 * return from ib_sa_multicast_join and set mcast->mc to a
+	 * valid value.  Otherwise we were racing with ourselves in
+	 * that we might fail here, but get a valid return from
+	 * ib_sa_multicast_join after we had cleared mcast->mc here,
+	 * resulting in mis-matched joins and leaves and a deadlock
+	 */
+	mutex_lock(&mcast_mutex);
+
 	/* We trap for port events ourselves. */
 	if (status == -ENETRESET) {
 		status = 0;
@@ -401,10 +476,8 @@ static int ipoib_mcast_join_complete(int status,
 
 	if (!status) {
 		mcast->backoff = 1;
-		mutex_lock(&mcast_mutex);
-		if (test_bit(IPOIB_MCAST_RUN, &priv->flags))
-			queue_delayed_work(priv->wq, &priv->mcast_task, 0);
-		mutex_unlock(&mcast_mutex);
+		mcast->delay_until = jiffies;
+		__ipoib_mcast_schedule_join_thread(priv, NULL, 0);
 
 		/*
 		 * Defer carrier on work to priv->wq to avoid a
@@ -412,37 +485,26 @@ static int ipoib_mcast_join_complete(int status,
 		 */
 		if (mcast == priv->broadcast)
 			queue_work(priv->wq, &priv->carrier_on_task);
-
-		status = 0;
-		goto out;
-	}
-
-	if (mcast->logcount++ < 20) {
-		if (status == -ETIMEDOUT || status == -EAGAIN) {
-			ipoib_dbg_mcast(priv, "multicast join failed for %pI6, status %d\n",
-					mcast->mcmember.mgid.raw, status);
-		} else {
-			ipoib_warn(priv, "multicast join failed for %pI6, status %d\n",
-				   mcast->mcmember.mgid.raw, status);
+	} else {
+		if (mcast->logcount++ < 20) {
+			if (status == -ETIMEDOUT || status == -EAGAIN) {
+				ipoib_dbg_mcast(priv, "multicast join failed for %pI6, status %d\n",
+						mcast->mcmember.mgid.raw, status);
+			} else {
+				ipoib_warn(priv, "multicast join failed for %pI6, status %d\n",
+					   mcast->mcmember.mgid.raw, status);
+			}
 		}
-	}
-
-	mcast->backoff *= 2;
-	if (mcast->backoff > IPOIB_MAX_BACKOFF_SECONDS)
-		mcast->backoff = IPOIB_MAX_BACKOFF_SECONDS;
 
-	/* Clear the busy flag so we try again */
-	status = test_and_clear_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags);
-
-	mutex_lock(&mcast_mutex);
-	spin_lock_irq(&priv->lock);
-	if (test_bit(IPOIB_MCAST_RUN, &priv->flags))
-		queue_delayed_work(priv->wq, &priv->mcast_task,
-				   mcast->backoff * HZ);
-	spin_unlock_irq(&priv->lock);
-	mutex_unlock(&mcast_mutex);
+		/* Requeue this join task with a backoff delay */
+		__ipoib_mcast_schedule_join_thread(priv, mcast, 1);
+	}
 out:
+	clear_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags);
+	if (status)
+		mcast->mc = NULL;
 	complete(&mcast->done);
+	mutex_unlock(&mcast_mutex);
 	return status;
 }
 
@@ -491,29 +553,18 @@ static void ipoib_mcast_join(struct net_device *dev, struct ipoib_mcast *mcast,
 		rec.hop_limit	  = priv->broadcast->mcmember.hop_limit;
 	}
 
-	set_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags);
-	init_completion(&mcast->done);
-	set_bit(IPOIB_MCAST_JOIN_STARTED, &mcast->flags);
-
+	mutex_lock(&mcast_mutex);
 	mcast->mc = ib_sa_join_multicast(&ipoib_sa_client, priv->ca, priv->port,
 					 &rec, comp_mask, GFP_KERNEL,
 					 ipoib_mcast_join_complete, mcast);
 	if (IS_ERR(mcast->mc)) {
 		clear_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags);
-		complete(&mcast->done);
 		ret = PTR_ERR(mcast->mc);
 		ipoib_warn(priv, "ib_sa_join_multicast failed, status %d\n", ret);
-
-		mcast->backoff *= 2;
-		if (mcast->backoff > IPOIB_MAX_BACKOFF_SECONDS)
-			mcast->backoff = IPOIB_MAX_BACKOFF_SECONDS;
-
-		mutex_lock(&mcast_mutex);
-		if (test_bit(IPOIB_MCAST_RUN, &priv->flags))
-			queue_delayed_work(priv->wq, &priv->mcast_task,
-					   mcast->backoff * HZ);
-		mutex_unlock(&mcast_mutex);
+		__ipoib_mcast_schedule_join_thread(priv, mcast, 1);
+		complete(&mcast->done);
 	}
+	mutex_unlock(&mcast_mutex);
 }
 
 void ipoib_mcast_join_task(struct work_struct *work)
@@ -522,6 +573,9 @@ void ipoib_mcast_join_task(struct work_struct *work)
 		container_of(work, struct ipoib_dev_priv, mcast_task.work);
 	struct net_device *dev = priv->dev;
 	struct ib_port_attr port_attr;
+	unsigned long delay_until = 0;
+	struct ipoib_mcast *mcast = NULL;
+	int create = 1;
 
 	if (!test_bit(IPOIB_MCAST_RUN, &priv->flags))
 		return;
@@ -539,64 +593,102 @@ void ipoib_mcast_join_task(struct work_struct *work)
 	else
 		memcpy(priv->dev->dev_addr + 4, priv->local_gid.raw, sizeof (union ib_gid));
 
+	/*
+	 * We have to hold the mutex to keep from racing with the join
+	 * completion threads on setting flags on mcasts, and we have
+	 * to hold the priv->lock because dev_flush will remove entries
+	 * out from underneath us, so at a minimum we need the lock
+	 * through the time that we do the for_each loop of the mcast
+	 * list or else dev_flush can make us oops.
+	 */
+	mutex_lock(&mcast_mutex);
+	spin_lock_irq(&priv->lock);
+	if (!test_bit(IPOIB_FLAG_OPER_UP, &priv->flags))
+		goto out;
+
 	if (!priv->broadcast) {
 		struct ipoib_mcast *broadcast;
 
-		if (!test_bit(IPOIB_FLAG_OPER_UP, &priv->flags))
-			return;
-
-		broadcast = ipoib_mcast_alloc(dev, 1);
+		broadcast = ipoib_mcast_alloc(dev, 0);
 		if (!broadcast) {
 			ipoib_warn(priv, "failed to allocate broadcast group\n");
-			mutex_lock(&mcast_mutex);
-			if (test_bit(IPOIB_MCAST_RUN, &priv->flags))
-				queue_delayed_work(priv->wq, &priv->mcast_task,
-						   HZ);
-			mutex_unlock(&mcast_mutex);
-			return;
+			/*
+			 * Restart us after a 1 second delay to retry
+			 * creating our broadcast group and attaching to
+			 * it.  Until this succeeds, this ipoib dev is
+			 * completely stalled (multicast wise).
+			 */
+			__ipoib_mcast_schedule_join_thread(priv, NULL, 1);
+			goto out;
 		}
 
-		spin_lock_irq(&priv->lock);
 		memcpy(broadcast->mcmember.mgid.raw, priv->dev->broadcast + 4,
 		       sizeof (union ib_gid));
 		priv->broadcast = broadcast;
 
 		__ipoib_mcast_add(dev, priv->broadcast);
-		spin_unlock_irq(&priv->lock);
 	}
 
 	if (!test_bit(IPOIB_MCAST_FLAG_ATTACHED, &priv->broadcast->flags)) {
-		if (!test_bit(IPOIB_MCAST_FLAG_BUSY, &priv->broadcast->flags))
-			ipoib_mcast_join(dev, priv->broadcast, 0);
-		return;
+		if (IS_ERR_OR_NULL(priv->broadcast->mc) &&
+		    !test_bit(IPOIB_MCAST_FLAG_BUSY, &priv->broadcast->flags)) {
+			mcast = priv->broadcast;
+			create = 0;
+			if (mcast->backoff > 1 &&
+			    time_before(jiffies, mcast->delay_until)) {
+				delay_until = mcast->delay_until;
+				mcast = NULL;
+			}
+		}
+		goto out;
 	}
 
-	while (1) {
-		struct ipoib_mcast *mcast = NULL;
-
-		spin_lock_irq(&priv->lock);
-		list_for_each_entry(mcast, &priv->multicast_list, list) {
-			if (!test_bit(IPOIB_MCAST_FLAG_SENDONLY, &mcast->flags)
-			    && !test_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags)
-			    && !test_bit(IPOIB_MCAST_FLAG_ATTACHED, &mcast->flags)) {
+	/*
+	 * We'll never get here until the broadcast group is both allocated
+	 * and attached
+	 */
+	list_for_each_entry(mcast, &priv->multicast_list, list) {
+		if (IS_ERR_OR_NULL(mcast->mc) &&
+		    !test_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags) &&
+		    !test_bit(IPOIB_MCAST_FLAG_ATTACHED, &mcast->flags)) {
+			if (mcast->backoff == 1 ||
+			    time_after_eq(jiffies, mcast->delay_until))
 				/* Found the next unjoined group */
 				break;
-			}
+			else if (!delay_until ||
+				 time_before(mcast->delay_until, delay_until))
+				delay_until = mcast->delay_until;
 		}
-		spin_unlock_irq(&priv->lock);
-
-		if (&mcast->list == &priv->multicast_list) {
-			/* All done */
-			break;
-		}
-
-		ipoib_mcast_join(dev, mcast, 1);
-		return;
 	}
 
-	ipoib_dbg_mcast(priv, "successfully joined all multicast groups\n");
+	if (&mcast->list == &priv->multicast_list) {
+		/*
+		 * All done, unless we have delayed work from
+		 * backoff retransmissions, but we will get
+		 * restarted when the time is right, so we are
+		 * done for now
+		 */
+		mcast = NULL;
+		ipoib_dbg_mcast(priv, "successfully joined all "
+				"multicast groups\n");
+	}
 
-	clear_bit(IPOIB_MCAST_RUN, &priv->flags);
+out:
+	if (mcast) {
+		init_completion(&mcast->done);
+		set_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags);
+	}
+	spin_unlock_irq(&priv->lock);
+	mutex_unlock(&mcast_mutex);
+	if (mcast) {
+		if (test_bit(IPOIB_MCAST_FLAG_SENDONLY, &mcast->flags))
+			ipoib_mcast_sendonly_join(mcast);
+		else
+			ipoib_mcast_join(dev, mcast, create);
+	}
+	if (delay_until)
+		queue_delayed_work(priv->wq, &priv->mcast_task,
+				   delay_until - jiffies);
 }
 
 int ipoib_mcast_start_thread(struct net_device *dev)
@@ -606,8 +698,8 @@ int ipoib_mcast_start_thread(struct net_device *dev)
 	ipoib_dbg_mcast(priv, "starting multicast thread\n");
 
 	mutex_lock(&mcast_mutex);
-	if (!test_and_set_bit(IPOIB_MCAST_RUN, &priv->flags))
-		queue_delayed_work(priv->wq, &priv->mcast_task, 0);
+	set_bit(IPOIB_MCAST_RUN, &priv->flags);
+	__ipoib_mcast_schedule_join_thread(priv, NULL, 0);
 	mutex_unlock(&mcast_mutex);
 
 	return 0;
@@ -635,7 +727,12 @@ static int ipoib_mcast_leave(struct net_device *dev, struct ipoib_mcast *mcast)
 	int ret = 0;
 
 	if (test_and_clear_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags))
+		ipoib_warn(priv, "ipoib_mcast_leave on an in-flight join\n");
+
+	if (!IS_ERR_OR_NULL(mcast->mc))
 		ib_sa_free_multicast(mcast->mc);
+	else
+		ipoib_dbg(priv, "ipoib_mcast_leave with mcast->mc invalid\n");
 
 	if (test_and_clear_bit(IPOIB_MCAST_FLAG_ATTACHED, &mcast->flags)) {
 		ipoib_dbg_mcast(priv, "leaving MGID %pI6\n",
@@ -646,7 +743,9 @@ static int ipoib_mcast_leave(struct net_device *dev, struct ipoib_mcast *mcast)
 				      be16_to_cpu(mcast->mcmember.mlid));
 		if (ret)
 			ipoib_warn(priv, "ib_detach_mcast failed (result = %d)\n", ret);
-	}
+	} else if (!test_bit(IPOIB_MCAST_FLAG_SENDONLY, &mcast->flags))
+		ipoib_dbg(priv, "leaving with no mcmember but not a "
+			  "SENDONLY join\n");
 
 	return 0;
 }
@@ -687,6 +786,7 @@ void ipoib_mcast_send(struct net_device *dev, u8 *daddr, struct sk_buff *skb)
 		memcpy(mcast->mcmember.mgid.raw, mgid, sizeof (union ib_gid));
 		__ipoib_mcast_add(dev, mcast);
 		list_add_tail(&mcast->list, &priv->multicast_list);
+		__ipoib_mcast_schedule_join_thread(priv, NULL, 0);
 	}
 
 	if (!mcast->ah) {
@@ -696,13 +796,6 @@ void ipoib_mcast_send(struct net_device *dev, u8 *daddr, struct sk_buff *skb)
 			++dev->stats.tx_dropped;
 			dev_kfree_skb_any(skb);
 		}
-
-		if (test_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags))
-			ipoib_dbg_mcast(priv, "no address vector, "
-					"but multicast join already started\n");
-		else if (test_bit(IPOIB_MCAST_FLAG_SENDONLY, &mcast->flags))
-			ipoib_mcast_sendonly_join(mcast);
-
 		/*
 		 * If lookup completes between here and out:, don't
 		 * want to send packet twice.
@@ -761,9 +854,12 @@ void ipoib_mcast_dev_flush(struct net_device *dev)
 
 	spin_unlock_irqrestore(&priv->lock, flags);
 
-	/* seperate between the wait to the leave*/
+	/*
+	 * make sure the in-flight joins have finished before we attempt
+	 * to leave
+	 */
 	list_for_each_entry_safe(mcast, tmcast, &remove_list, list)
-		if (test_bit(IPOIB_MCAST_JOIN_STARTED, &mcast->flags))
+		if (test_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags))
 			wait_for_completion(&mcast->done);
 
 	list_for_each_entry_safe(mcast, tmcast, &remove_list, list) {
@@ -794,20 +890,14 @@ void ipoib_mcast_restart_task(struct work_struct *work)
 	unsigned long flags;
 	struct ib_sa_mcmember_rec rec;
 
-	ipoib_dbg_mcast(priv, "restarting multicast task\n");
+	if (!test_bit(IPOIB_FLAG_OPER_UP, &priv->flags))
+		/*
+		 * shortcut...on shutdown flush is called next, just
+		 * let it do all the work
+		 */
+		return;
 
-	/*
-	 * We're running on the priv->wq right now, so we can't call
-	 * mcast_stop_thread as it wants to flush the wq and that
-	 * will deadlock.  We don't actually *need* to stop the
-	 * thread here anyway, so just clear the run flag, cancel
-	 * any delayed work, do our work, remove the old entries,
-	 * then restart the thread.
-	 */
-	mutex_lock(&mcast_mutex);
-	clear_bit(IPOIB_MCAST_RUN, &priv->flags);
-	cancel_delayed_work(&priv->mcast_task);
-	mutex_unlock(&mcast_mutex);
+	ipoib_dbg_mcast(priv, "restarting multicast task\n");
 
 	local_irq_save(flags);
 	netif_addr_lock(dev);
@@ -893,14 +983,27 @@ void ipoib_mcast_restart_task(struct work_struct *work)
 	netif_addr_unlock(dev);
 	local_irq_restore(flags);
 
-	/* We have to cancel outside of the spinlock */
+	/*
+	 * make sure the in-flight joins have finished before we attempt
+	 * to leave
+	 */
+	list_for_each_entry_safe(mcast, tmcast, &remove_list, list)
+		if (test_bit(IPOIB_MCAST_FLAG_BUSY, &mcast->flags))
+			wait_for_completion(&mcast->done);
+
 	list_for_each_entry_safe(mcast, tmcast, &remove_list, list) {
 		ipoib_mcast_leave(mcast->dev, mcast);
 		ipoib_mcast_free(mcast);
 	}
 
-	if (test_bit(IPOIB_FLAG_OPER_UP, &priv->flags))
-		ipoib_mcast_start_thread(dev);
+	/*
+	 * Double check that we are still up
+	 */
+	if (test_bit(IPOIB_FLAG_OPER_UP, &priv->flags)) {
+		spin_lock_irqsave(&priv->lock, flags);
+		__ipoib_mcast_schedule_join_thread(priv, NULL, 0);
+		spin_unlock_irqrestore(&priv->lock, flags);
+	}
 }
 
 #ifdef CONFIG_INFINIBAND_IPOIB_DEBUG