Revert "IPoIB: fix mcast_dev_flush/mcast_restart_task race"

This reverts commit e5d1dcf1b0951f4ba00d93653942dda6196109d8.

The series of IPoIB bug fixes that went into 3.19-rc1 introduce
regressions, and after trying to sort things out, we decided to revert
to 3.18's IPoIB driver and get things right for 3.20.

Signed-off-by: Roland Dreier <roland@purestorage.com>

1 files changed, 5 insertions, 32 deletions

diff --git a/drivers/infiniband/ulp/ipoib/ipoib_multicast.c b/drivers/infiniband/ulp/ipoib/ipoib_multicast.c
index 41325960e4e0..a52c9f3f7e42 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib_multicast.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_multicast.c
@@ -802,10 +802,7 @@ void ipoib_mcast_dev_flush(struct net_device *dev)
 
         spin_unlock_irqrestore(&priv->lock, flags);
 
-        /*
-         * make sure the in-flight joins have finished before we attempt
-         * to leave
-         */
+        /* seperate between the wait to the 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);
@@ -926,38 +923,14 @@ void ipoib_mcast_restart_task(struct work_struct *work)
         netif_addr_unlock(dev);
         local_irq_restore(flags);
 
-        /*
-         * 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);
-
-        /*
-         * 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_dev_flush.
-         */
-        while (!rtnl_trylock()) {
-                if (!test_bit(IPOIB_FLAG_ADMIN_UP, &priv->flags))
-                        return;
-                else
-                        msleep(20);
-        }
+        /* We have to cancel outside of the spinlock */
         list_for_each_entry_safe(mcast, tmcast, &remove_list, list) {
                 ipoib_mcast_leave(mcast->dev, mcast);
                 ipoib_mcast_free(mcast);
         }
-        ipoib_mcast_start_thread(dev);
-        rtnl_unlock();
+
+        if (test_bit(IPOIB_FLAG_ADMIN_UP, &priv->flags))
+                ipoib_mcast_start_thread(dev);
 }
 
 #ifdef CONFIG_INFINIBAND_IPOIB_DEBUG