Upon receipt of the NETDEV_REGISTER event from the netdev notifier chain,
the IB stack registration is spawned off to a workqueue since that also
requires an rtnl lock.
There could be 2 kinds of races between the NETDEV_REGISTER and the
NETDEV_UNREGISTER event handling.
a)The NETDEV_UNREGISTER event is received in rapid succession after
the NETDEV_REGISTER event even before the work queue got a chance to run.
b)The NETDEV_UNREGISTER event is received while the workqueue that handles
registration with the IB stack is still in progress.
Handle both the races with a bit flag that is set just before the work item
is queued and cleared in the workqueue after the event is handled just
before the workqueue item is freed.
Signed-off-by: Somnath Kotur <somnath.kotur@xxxxxxxxxxxx>
---
drivers/infiniband/hw/bnxt_re/bnxt_re.h | 12 +++++++-----
drivers/infiniband/hw/bnxt_re/main.c | 8 ++++++++
2 files changed, 15 insertions(+), 5 deletions(-)
diff --git a/drivers/infiniband/hw/bnxt_re/bnxt_re.h b/drivers/infiniband/hw/bnxt_re/bnxt_re.h
index b3ad37f..a25f9d2 100644
--- a/drivers/infiniband/hw/bnxt_re/bnxt_re.h
+++ b/drivers/infiniband/hw/bnxt_re/bnxt_re.h
@@ -93,11 +93,13 @@ struct bnxt_re_dev {
struct ib_device ibdev;
struct list_head list;
unsigned long flags;
-#define BNXT_RE_FLAG_NETDEV_REGISTERED 0
-#define BNXT_RE_FLAG_IBDEV_REGISTERED 1
-#define BNXT_RE_FLAG_GOT_MSIX 2
-#define BNXT_RE_FLAG_RCFW_CHANNEL_EN 8
-#define BNXT_RE_FLAG_QOS_WORK_REG 16
+#define BNXT_RE_FLAG_NETDEV_REGISTERED 0
+#define BNXT_RE_FLAG_IBDEV_REGISTERED 1
+#define BNXT_RE_FLAG_GOT_MSIX 2
+#define BNXT_RE_FLAG_HAVE_L2_REF 3
+#define BNXT_RE_FLAG_RCFW_CHANNEL_EN 4
+#define BNXT_RE_FLAG_QOS_WORK_REG 5
+#define BNXT_RE_FLAG_TASK_IN_PROG 6
struct net_device *netdev;
unsigned int version, major, minor;
struct bnxt_en_dev *en_dev;
diff --git a/drivers/infiniband/hw/bnxt_re/main.c b/drivers/infiniband/hw/bnxt_re/main.c
index 00a3b74..29c3d7e 100644
--- a/drivers/infiniband/hw/bnxt_re/main.c
+++ b/drivers/infiniband/hw/bnxt_re/main.c
@@ -1259,6 +1259,8 @@ static void bnxt_re_task(struct work_struct *work)
default:
break;
}
+ smp_mb__before_atomic();
+ clear_bit(BNXT_RE_FLAG_TASK_IN_PROG, &rdev->flags);
kfree(re_work);
}
@@ -1317,6 +1319,11 @@ static int bnxt_re_netdev_event(struct notifier_block *notifier,
break;
case NETDEV_UNREGISTER:
+ /* netdev notifier will call NETDEV_UNREGISTER again later since
+ * we are still holding the reference to the netdev
+ */
+ if (test_bit(BNXT_RE_FLAG_TASK_IN_PROG, &rdev->flags))
+ goto exit;
bnxt_re_ib_unreg(rdev, false);
bnxt_re_remove_one(rdev);
bnxt_re_dev_unreg(rdev);
@@ -1335,6 +1342,7 @@ static int bnxt_re_netdev_event(struct notifier_block *notifier,
re_work->vlan_dev = (real_dev == netdev ?
NULL : netdev);
INIT_WORK(&re_work->work, bnxt_re_task);
+ set_bit(BNXT_RE_FLAG_TASK_IN_PROG, &rdev->flags);
queue_work(bnxt_re_wq, &re_work->work);
}
}
--
1.8.3.1
--
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