bnxt_re: Remove RTNL lock dependency in bnxt_re_query_port

When there is a NETDEV_UNREGISTER event, bnxt_re driver calls
ib_unregister_device() (RTNL lock held).
ib_unregister_device attempts to flush a worker queue scheduled by
ib_core and that queue might have a pending ib_query_port().
ib_query_port in turn calls bnxt_re_query_port(), which while querying the
link speed using ib_get_eth_speed(), tries to acquire the rtnl_lock() which
was already held by NETDEV_UNREGISTER.
Fixing the issue by removing the link speed query from bnxt_re_query_port()
Now the speed is queried post a successful ib_register_device or whenever
there is a NETDEV_CHANGE event.

Signed-off-by: Somnath Kotur <somnath.kotur@broadcom.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

3 files changed, 9 insertions, 8 deletions

diff --git a/drivers/infiniband/hw/bnxt_re/bnxt_re.h b/drivers/infiniband/hw/bnxt_re/bnxt_re.h
index a25f9d240880..ecbac91b2e14 100644
--- a/drivers/infiniband/hw/bnxt_re/bnxt_re.h
+++ b/drivers/infiniband/hw/bnxt_re/bnxt_re.h
@@ -110,6 +110,8 @@ struct bnxt_re_dev {
 
         struct delayed_work             worker;
         u8                              cur_prio_map;
+        u8                              active_speed;
+        u8                              active_width;
 
         /* FP Notification Queue (CQ & SRQ) */
         struct tasklet_struct           nq_task;
diff --git a/drivers/infiniband/hw/bnxt_re/ib_verbs.c b/drivers/infiniband/hw/bnxt_re/ib_verbs.c
index 0dbdbe1616ab..7430ef07a0e1 100644
--- a/drivers/infiniband/hw/bnxt_re/ib_verbs.c
+++ b/drivers/infiniband/hw/bnxt_re/ib_verbs.c
@@ -259,14 +259,9 @@ int bnxt_re_query_port(struct ib_device *ibdev, u8 port_num,
         port_attr->sm_sl = 0;
         port_attr->subnet_timeout = 0;
         port_attr->init_type_reply = 0;
-        /* call the underlying netdev's ethtool hooks to query speed settings
-         * for which we acquire rtnl_lock _only_ if it's registered with
-         * IB stack to avoid race in the NETDEV_UNREG path
-         */
-        if (test_bit(BNXT_RE_FLAG_IBDEV_REGISTERED, &rdev->flags))
-                if (ib_get_eth_speed(ibdev, port_num, &port_attr->active_speed,
-                                     &port_attr->active_width))
-                        return -EINVAL;
+        port_attr->active_speed = rdev->active_speed;
+        port_attr->active_width = rdev->active_width;
+
         return 0;
 }
 
diff --git a/drivers/infiniband/hw/bnxt_re/main.c b/drivers/infiniband/hw/bnxt_re/main.c
index 29c3d7e254af..e7450ea92aa9 100644
--- a/drivers/infiniband/hw/bnxt_re/main.c
+++ b/drivers/infiniband/hw/bnxt_re/main.c
@@ -1161,6 +1161,8 @@ static int bnxt_re_ib_reg(struct bnxt_re_dev *rdev)
                 }
         }
         set_bit(BNXT_RE_FLAG_IBDEV_REGISTERED, &rdev->flags);
+        ib_get_eth_speed(&rdev->ibdev, 1, &rdev->active_speed,
+                         &rdev->active_width);
         bnxt_re_dispatch_event(&rdev->ibdev, NULL, 1, IB_EVENT_PORT_ACTIVE);
         bnxt_re_dispatch_event(&rdev->ibdev, NULL, 1, IB_EVENT_GID_CHANGE);
 
@@ -1255,6 +1257,8 @@ static void bnxt_re_task(struct work_struct *work)
                 else if (netif_carrier_ok(rdev->netdev))
                         bnxt_re_dispatch_event(&rdev->ibdev, NULL, 1,
                                                IB_EVENT_PORT_ACTIVE);
+                ib_get_eth_speed(&rdev->ibdev, 1, &rdev->active_speed,
+                                 &rdev->active_width);
                 break;
         default:
                 break;