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Commit 5bb3c1e9 authored by Parvi Kaustubhi's avatar Parvi Kaustubhi Committed by Jason Gunthorpe
Browse files

IB/usnic: Fix deadlock 



There is a dead lock in usnic ib_register and netdev_notify path.

	usnic_ib_discover_pf()
	| mutex_lock(&usnic_ib_ibdev_list_lock);
	 | usnic_ib_device_add();
	  | ib_register_device()
	   | usnic_ib_query_port()
	    | mutex_lock(&us_ibdev->usdev_lock);
	     | ib_get_eth_speed()
	      | rtnl_lock()

order of lock: &usnic_ib_ibdev_list_lock -> usdev_lock -> rtnl_lock

	rtnl_lock()
	 | usnic_ib_netdevice_event()
	  | mutex_lock(&usnic_ib_ibdev_list_lock);

order of lock: rtnl_lock -> &usnic_ib_ibdev_list_lock

Solution is to use the core's lock-free ib_device_get_by_netdev() scheme
to lookup ib_dev while handling netdev & inet events.

Signed-off-by: default avatarParvi Kaustubhi <pkaustub@cisco.com>
Reviewed-by: default avatarGovindarajulu Varadarajan <gvaradar@cisco.com>
Reviewed-by: default avatarTanmay Inamdar <tinamdar@cisco.com>
Signed-off-by: default avatarJason Gunthorpe <jgg@mellanox.com>
parent ca22354b

drivers/infiniband/hw/usnic/usnic_ib_main.c

+19 −17
Original line number Diff line number Diff line
@@ -216,18 +216,17 @@ static int usnic_ib_netdevice_event(struct notifier_block *notifier, 
					unsigned long event, void *ptr)

{

	struct usnic_ib_dev *us_ibdev;

	struct ib_device *ibdev;



	struct net_device *netdev = netdev_notifier_info_to_dev(ptr);



	mutex_lock(&usnic_ib_ibdev_list_lock);

	list_for_each_entry(us_ibdev, &usnic_ib_ibdev_list, ib_dev_link) {

		if (us_ibdev->netdev == netdev) {

			usnic_ib_handle_usdev_event(us_ibdev, event);

			break;

		}

	}

	mutex_unlock(&usnic_ib_ibdev_list_lock);

	ibdev = ib_device_get_by_netdev(netdev, RDMA_DRIVER_USNIC);

	if (!ibdev)

		return NOTIFY_DONE;



	us_ibdev = container_of(ibdev, struct usnic_ib_dev, ib_dev);

	usnic_ib_handle_usdev_event(us_ibdev, event);

	ib_device_put(ibdev);

	return NOTIFY_DONE;

}
@@ -282,16 +281,15 @@ static int usnic_ib_inetaddr_event(struct notifier_block *notifier, 
	struct usnic_ib_dev *us_ibdev;

	struct in_ifaddr *ifa = ptr;

	struct net_device *netdev = ifa->ifa_dev->dev;

	struct ib_device *ibdev;



	mutex_lock(&usnic_ib_ibdev_list_lock);

	list_for_each_entry(us_ibdev, &usnic_ib_ibdev_list, ib_dev_link) {

		if (us_ibdev->netdev == netdev) {

			usnic_ib_handle_inet_event(us_ibdev, event, ptr);

			break;

		}

	}

	mutex_unlock(&usnic_ib_ibdev_list_lock);

	ibdev = ib_device_get_by_netdev(netdev, RDMA_DRIVER_USNIC);

	if (!ibdev)

		return NOTIFY_DONE;



	us_ibdev = container_of(ibdev, struct usnic_ib_dev, ib_dev);

	usnic_ib_handle_inet_event(us_ibdev, event, ptr);

	ib_device_put(ibdev);

	return NOTIFY_DONE;

}

static struct notifier_block usnic_ib_inetaddr_notifier = {
@@ -342,7 +340,6 @@ static const struct ib_device_ops usnic_dev_ops = { 
	.destroy_qp = usnic_ib_destroy_qp,

	.get_dev_fw_str = usnic_get_dev_fw_str,

	.get_link_layer = usnic_ib_port_link_layer,

	.get_netdev = usnic_get_netdev,

	.get_port_immutable = usnic_port_immutable,

	.mmap = usnic_ib_mmap,

	.modify_qp = usnic_ib_modify_qp,
@@ -362,6 +359,7 @@ static void *usnic_ib_device_add(struct pci_dev *dev) 
	union ib_gid gid;

	struct in_device *ind;

	struct net_device *netdev;

	int ret;



	usnic_dbg("\n");

	netdev = pci_get_drvdata(dev);
@@ -416,6 +414,10 @@ static void *usnic_ib_device_add(struct pci_dev *dev) 
	us_ibdev->ib_dev.driver_id = RDMA_DRIVER_USNIC;

	rdma_set_device_sysfs_group(&us_ibdev->ib_dev, &usnic_attr_group);



	ret = ib_device_set_netdev(&us_ibdev->ib_dev, us_ibdev->netdev, 1);

	if (ret)

		goto err_fwd_dealloc;



	if (ib_register_device(&us_ibdev->ib_dev, "usnic_%d"))

		goto err_fwd_dealloc;

drivers/infiniband/hw/usnic/usnic_ib_verbs.c

+0 −10
Original line number Diff line number Diff line
@@ -437,16 +437,6 @@ int usnic_ib_query_gid(struct ib_device *ibdev, u8 port, int index, 
	return 0;

}



struct net_device *usnic_get_netdev(struct ib_device *device, u8 port_num)

{

	struct usnic_ib_dev *us_ibdev = to_usdev(device);



	if (us_ibdev->netdev)

		dev_hold(us_ibdev->netdev);



	return us_ibdev->netdev;

}



int usnic_ib_query_pkey(struct ib_device *ibdev, u8 port, u16 index,

				u16 *pkey)

{

drivers/infiniband/hw/usnic/usnic_ib_verbs.h

+0 −1
Original line number Diff line number Diff line
@@ -48,7 +48,6 @@ int usnic_ib_query_qp(struct ib_qp *qp, struct ib_qp_attr *qp_attr, 
				struct ib_qp_init_attr *qp_init_attr);

int usnic_ib_query_gid(struct ib_device *ibdev, u8 port, int index,

				union ib_gid *gid);

struct net_device *usnic_get_netdev(struct ib_device *device, u8 port_num);

int usnic_ib_query_pkey(struct ib_device *ibdev, u8 port, u16 index,

				u16 *pkey);

int usnic_ib_alloc_pd(struct ib_pd *ibpd, struct ib_ucontext *context,