IB/mlx4: Fix lockdep splat for the iboe lock

Chuck Lever reported the following stack trace:

    =================================
    [ INFO: inconsistent lock state ]
    3.16.0-rc2-00024-g2e78883 #17 Tainted: G            E
    ---------------------------------
    inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
    swapper/0/0 [HC0[0]:SC1[1]:HE1:SE0] takes:
    (&(&iboe->lock)->rlock){+.?...}, at: [<ffffffffa065f68b>] mlx4_ib_addr_event+0xdb/0x1a0 [mlx4_ib]
    {SOFTIRQ-ON-W} state was registered at:
     [<ffffffff810b3110>] mark_irqflags+0x110/0x170
     [<ffffffff810b4806>] __lock_acquire+0x2c6/0x5b0
     [<ffffffff810b4bd9>] lock_acquire+0xe9/0x120
     [<ffffffff815f7f6e>] _raw_spin_lock+0x3e/0x80
     [<ffffffffa0661084>] mlx4_ib_scan_netdevs+0x34/0x260 [mlx4_ib]
     [<ffffffffa06612db>] mlx4_ib_netdev_event+0x2b/0x40 [mlx4_ib]
     [<ffffffff81522219>] register_netdevice_notifier+0x99/0x1e0
     [<ffffffffa06626e3>] mlx4_ib_add+0x743/0xbc0 [mlx4_ib]
     [<ffffffffa05ec168>] mlx4_add_device+0x48/0xa0 [mlx4_core]
     [<ffffffffa05ec2c3>] mlx4_register_interface+0x73/0xb0 [mlx4_core]
     [<ffffffffa05c505e>] cm_req_handler+0x13e/0x460 [ib_cm]
     [<ffffffff810002e2>] do_one_initcall+0x112/0x1c0
     [<ffffffff810e8264>] do_init_module+0x34/0x190
     [<ffffffff810ea62f>] load_module+0x5cf/0x740
     [<ffffffff810ea939>] SyS_init_module+0x99/0xd0
     [<ffffffff815f8fd2>] system_call_fastpath+0x16/0x1b
    irq event stamp: 336142
    hardirqs last  enabled at (336142): [<ffffffff810612f5>] __local_bh_enable_ip+0xb5/0xc0
    hardirqs last disabled at (336141): [<ffffffff81061296>] __local_bh_enable_ip+0x56/0xc0
    softirqs last  enabled at (336004): [<ffffffff8106123a>] _local_bh_enable+0x4a/0x50
    softirqs last disabled at (336005): [<ffffffff810617a4>] irq_exit+0x44/0xd0

    other info that might help us debug this:
    Possible unsafe locking scenario:

          CPU0
          ----
     lock(&(&iboe->lock)->rlock);
     <Interrupt>
       lock(&(&iboe->lock)->rlock);

    *** DEADLOCK ***

The above problem was caused by the spin lock being taken both in the process
context and in a soft-irq context (in a netdev notifier handler).

The required fix is to use spin_lock/unlock_bh() instead of spin_lock/unlock
on the iboe lock.

Reported-by: Chuck Lever <[email protected]>
Signed-off-by: Jack Morgenstein <[email protected]>
Signed-off-by: Or Gerlitz <[email protected]>
Signed-off-by: Roland Dreier <[email protected]>

Author: Jack Morgenstein

drivers/infiniband/hw/mlx4/main.c

@@ -360,7 +360,7 @@ static int eth_link_query_port(struct ib_device *ibdev, u8 port,
 	props->state		= IB_PORT_DOWN;
 	props->phys_state	= state_to_phys_state(props->state);
 	props->active_mtu	= IB_MTU_256;
-	spin_lock(&iboe->lock);
+	spin_lock_bh(&iboe->lock);
 	ndev = iboe->netdevs[port - 1];
 	if (!ndev)
 		goto out_unlock;
@@ -372,7 +372,7 @@ static int eth_link_query_port(struct ib_device *ibdev, u8 port,
 					IB_PORT_ACTIVE : IB_PORT_DOWN;
 	props->phys_state	= state_to_phys_state(props->state);
 out_unlock:
-	spin_unlock(&iboe->lock);
+	spin_unlock_bh(&iboe->lock);
 out:
 	mlx4_free_cmd_mailbox(mdev->dev, mailbox);
 	return err;
@@ -814,11 +814,11 @@ int mlx4_ib_add_mc(struct mlx4_ib_dev *mdev, struct mlx4_ib_qp *mqp,
 	if (!mqp->port)
 		return 0;
 
-	spin_lock(&mdev->iboe.lock);
+	spin_lock_bh(&mdev->iboe.lock);
 	ndev = mdev->iboe.netdevs[mqp->port - 1];
 	if (ndev)
 		dev_hold(ndev);
-	spin_unlock(&mdev->iboe.lock);
+	spin_unlock_bh(&mdev->iboe.lock);
 
 	if (ndev) {
 		ret = 1;
@@ -1265,11 +1265,11 @@ static int mlx4_ib_mcg_detach(struct ib_qp *ibqp, union ib_gid *gid, u16 lid)
 	mutex_lock(&mqp->mutex);
 	ge = find_gid_entry(mqp, gid->raw);
 	if (ge) {
-		spin_lock(&mdev->iboe.lock);
+		spin_lock_bh(&mdev->iboe.lock);
 		ndev = ge->added ? mdev->iboe.netdevs[ge->port - 1] : NULL;
 		if (ndev)
 			dev_hold(ndev);
-		spin_unlock(&mdev->iboe.lock);
+		spin_unlock_bh(&mdev->iboe.lock);
 		if (ndev)
 			dev_put(ndev);
 		list_del(&ge->list);
@@ -1554,7 +1554,7 @@ static int mlx4_ib_addr_event(int event, struct net_device *event_netdev,
 		return 0;
 
 	iboe = &ibdev->iboe;
-	spin_lock(&iboe->lock);
+	spin_lock_bh(&iboe->lock);
 
 	for (port = 1; port <= ibdev->dev->caps.num_ports; ++port)
 		if ((netif_is_bond_master(real_dev) &&
@@ -1564,7 +1564,7 @@ static int mlx4_ib_addr_event(int event, struct net_device *event_netdev,
 			update_gid_table(ibdev, port, gid,
 					 event == NETDEV_DOWN, 0);
 
-	spin_unlock(&iboe->lock);
+	spin_unlock_bh(&iboe->lock);
 	return 0;
 
 }
@@ -1742,7 +1742,7 @@ static int mlx4_ib_init_gid_table(struct mlx4_ib_dev *ibdev)
 	}
 
 	read_lock(&dev_base_lock);
-	spin_lock(&iboe->lock);
+	spin_lock_bh(&iboe->lock);
 
 	for_each_netdev(&init_net, dev) {
 		u8 port = mlx4_ib_get_dev_port(dev, ibdev);
@@ -1753,7 +1753,7 @@ static int mlx4_ib_init_gid_table(struct mlx4_ib_dev *ibdev)
 		}
 	}
 
-	spin_unlock(&iboe->lock);
+	spin_unlock_bh(&iboe->lock);
 	read_unlock(&dev_base_lock);
 out:
 	return err;
@@ -1770,7 +1770,7 @@ static void mlx4_ib_scan_netdevs(struct mlx4_ib_dev *ibdev,
 
 	iboe = &ibdev->iboe;
 
-	spin_lock(&iboe->lock);
+	spin_lock_bh(&iboe->lock);
 	mlx4_foreach_ib_transport_port(port, ibdev->dev) {
 		enum ib_port_state	port_state = IB_PORT_NOP;
 		struct net_device *old_master = iboe->masters[port - 1];
@@ -1842,7 +1842,7 @@ static void mlx4_ib_scan_netdevs(struct mlx4_ib_dev *ibdev,
 		}
 	}
 
-	spin_unlock(&iboe->lock);
+	spin_unlock_bh(&iboe->lock);
 
 	if (update_qps_port > 0)
 		mlx4_ib_update_qps(ibdev, dev, update_qps_port);