IB/ipoib: Fix race between light events and interface restart

A potential race between light_event and interface restart
may attach multicast group to an already attached QP.

Scenario:
light_event flow goes through ipoib_mcast_dev_flush function,
if a context switch occurs before calling ipoib_mcast_remove_list,
then we may face a situation where the broadcast of the priv is null
and the corresponding QP is not detached yet.
If an "interface restart" runs during the previous context switch,
the following scenario occurs:
When the device goes up, ipoib_ib_dev_up function will be called,
it will send a new registration request to the broadcast group and then
attach the group to the QP that was not detached before.

     IPOIB_FLUSH_LIGHT                                          INTERFACE RESTART

    __ipoib_ib_dev_flush                                                |
        |                                                               |
        |                                                               |
        |                                                               |
    ipoib_mcast_dev_flush                                               |
    Move mcast list and broadcast to remove_list                        |
        |                                                               |
        |                                                               |
    Context Switch-->                                                   |
        |                                                       ipoib_ib_dev_down
        |                                                               |
        |                                                               |
        |                                                       ipoib_ib_dev_up
        |                                                               |
        |                                                               |
        |                                                       ipoib_mcast_join_task
        |                                                       allocate new broadcast
        |                                                               |
        |                                                               |
        |                                                       Attach QP to multicast group
        |                                                               |
        |                                                               |
        |                                                       <--Context Switch
    ipoib_mcast_leave
    Detach QP from multicast group

Signed-off-by: Feras Daoud <ferasda@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>

diff --git a/drivers/infiniband/ulp/ipoib/ipoib.h b/drivers/infiniband/ulp/ipoib/ipoib.h
index ff50a7bd66d864506ec65aef1b63f45ce5d36e36..7ac25059c40f94aad951b28351cf425ebe573197 100644 (file)
--- a/drivers/infiniband/ulp/ipoib/ipoib.h
+++ b/drivers/infiniband/ulp/ipoib/ipoib.h
@@ -336,6 +336,7 @@ struct ipoib_dev_priv {
        unsigned long flags;
 
        struct rw_semaphore vlan_rwsem;
+       struct mutex mcast_mutex;
 
        struct rb_root  path_tree;
        struct list_head path_list;

diff --git a/drivers/infiniband/ulp/ipoib/ipoib_main.c b/drivers/infiniband/ulp/ipoib/ipoib_main.c
index 4ce315c92b480fa705c30b33ffd7253b4cfded3b..144187b407bd54c7b3750a6bce96df28518372e0 100644 (file)
--- a/drivers/infiniband/ulp/ipoib/ipoib_main.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_main.c
@@ -1877,6 +1877,7 @@ static void ipoib_build_priv(struct net_device *dev)
        priv->dev = dev;
        spin_lock_init(&priv->lock);
        init_rwsem(&priv->vlan_rwsem);
+       mutex_init(&priv->mcast_mutex);
 
        INIT_LIST_HEAD(&priv->path_list);
        INIT_LIST_HEAD(&priv->child_intfs);

diff --git a/drivers/infiniband/ulp/ipoib/ipoib_multicast.c b/drivers/infiniband/ulp/ipoib/ipoib_multicast.c
index 057f58e6afca249744f2d9013021e3c1c5d6417f..0a0b2ce45cbc20502f9a9a78bab52b58628b9818 100644 (file)
--- a/drivers/infiniband/ulp/ipoib/ipoib_multicast.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_multicast.c
@@ -838,6 +838,7 @@ void ipoib_mcast_dev_flush(struct net_device *dev)
        struct ipoib_mcast *mcast, *tmcast;
        unsigned long flags;
 
+       mutex_lock(&priv->mcast_mutex);
        ipoib_dbg_mcast(priv, "flushing multicast list\n");
 
        spin_lock_irqsave(&priv->lock, flags);
@@ -865,6 +866,7 @@ void ipoib_mcast_dev_flush(struct net_device *dev)
                        wait_for_completion(&mcast->done);
 
        ipoib_mcast_remove_list(&remove_list);
+       mutex_unlock(&priv->mcast_mutex);
 }
 
 static int ipoib_mcast_addr_is_valid(const u8 *addr, const u8 *broadcast)