IPoIB: Make ipoib_mcast_stop_thread flush the workqueue

We used to pass a flush variable to mcast_stop_thread to indicate if
we should flush the workqueue or not.  This was due to some code
trying to flush a workqueue that it was currently running on which is
a no-no.  Now that we have per-device work queues, and now that
ipoib_mcast_restart_task has taken the fact that it is queued on a
single thread workqueue with all of the ipoib_mcast_join_task's and
therefore has no need to stop the join task while it runs, we can do
away with the flush parameter and unilaterally flush always.

Signed-off-by: Doug Ledford <dledford@redhat.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

3 files changed, 12 insertions, 15 deletions

diff --git a/drivers/infiniband/ulp/ipoib/ipoib.h b/drivers/infiniband/ulp/ipoib/ipoib.h
index 45fd10a72ec1..28dc927c0e8b 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib.h
+++ b/drivers/infiniband/ulp/ipoib/ipoib.h
@@ -499,7 +499,7 @@ void ipoib_mcast_send(struct net_device *dev, u8 *daddr, struct sk_buff *skb);
 
 void ipoib_mcast_restart_task(struct work_struct *work);
 int ipoib_mcast_start_thread(struct net_device *dev);
-int ipoib_mcast_stop_thread(struct net_device *dev, int flush);
+int ipoib_mcast_stop_thread(struct net_device *dev);
 
 void ipoib_mcast_dev_down(struct net_device *dev);
 void ipoib_mcast_dev_flush(struct net_device *dev);
diff --git a/drivers/infiniband/ulp/ipoib/ipoib_ib.c b/drivers/infiniband/ulp/ipoib/ipoib_ib.c
index bfd17d41b5f2..660967871191 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib_ib.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_ib.c
@@ -747,7 +747,7 @@ int ipoib_ib_dev_down(struct net_device *dev, int flush)
         clear_bit(IPOIB_FLAG_OPER_UP, &priv->flags);
         netif_carrier_off(dev);
 
-        ipoib_mcast_stop_thread(dev, flush);
+        ipoib_mcast_stop_thread(dev);
         ipoib_mcast_dev_flush(dev);
 
         ipoib_flush_paths(dev);
@@ -1097,7 +1097,7 @@ void ipoib_ib_dev_cleanup(struct net_device *dev)
          */
         ipoib_flush_paths(dev);
 
-        ipoib_mcast_stop_thread(dev, 1);
+        ipoib_mcast_stop_thread(dev);
         ipoib_mcast_dev_flush(dev);
 
         ipoib_transport_dev_cleanup(dev);
diff --git a/drivers/infiniband/ulp/ipoib/ipoib_multicast.c b/drivers/infiniband/ulp/ipoib/ipoib_multicast.c
index 845f910eb214..bc50dd0d0e4d 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib_multicast.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_multicast.c
@@ -648,7 +648,7 @@ int ipoib_mcast_start_thread(struct net_device *dev)
         return 0;
 }
 
-int ipoib_mcast_stop_thread(struct net_device *dev, int flush)
+int ipoib_mcast_stop_thread(struct net_device *dev)
 {
         struct ipoib_dev_priv *priv = netdev_priv(dev);
 
@@ -659,8 +659,7 @@ int ipoib_mcast_stop_thread(struct net_device *dev, int flush)
         cancel_delayed_work(&priv->mcast_task);
         mutex_unlock(&mcast_mutex);
 
-        if (flush)
-                flush_workqueue(priv->wq);
+        flush_workqueue(priv->wq);
 
         return 0;
 }
@@ -838,8 +837,6 @@ void ipoib_mcast_restart_task(struct work_struct *work)
 
         ipoib_dbg_mcast(priv, "restarting multicast task\n");
 
-        ipoib_mcast_stop_thread(dev, 0);
-
         local_irq_save(flags);
         netif_addr_lock(dev);
         spin_lock(&priv->lock);
@@ -936,13 +933,10 @@ void ipoib_mcast_restart_task(struct work_struct *work)
          * We have to cancel outside of the spinlock, but we have to
          * take the rtnl lock or else we race with the removal of
          * entries from the remove list in mcast_dev_flush as part
-         * of ipoib_stop() which will call mcast_stop_thread with
-         * flush == 1 while holding the rtnl lock, and the
-         * flush_workqueue won't complete until this restart_mcast_task
-         * completes.  So do like the carrier on task and attempt to
-         * take the rtnl lock, but if we can't before the ADMIN_UP flag
-         * goes away, then just return and know that the remove list will
-         * get flushed later by mcast_stop_thread.
+         * of ipoib_stop().  We detect the drop of the ADMIN_UP flag
+         * to signal that we have hit this particular race, and we
+         * return since we know we don't need to do anything else
+         * anyway.
          */
         while (!rtnl_trylock()) {
                 if (!test_bit(IPOIB_FLAG_ADMIN_UP, &priv->flags))
@@ -954,6 +948,9 @@ void ipoib_mcast_restart_task(struct work_struct *work)
                 ipoib_mcast_leave(mcast->dev, mcast);
                 ipoib_mcast_free(mcast);
         }
+        /*
+         * Restart our join task if needed
+         */
         ipoib_mcast_start_thread(dev);
         rtnl_unlock();
 }