From c5c504f4dc8c98a1c62d8cee2cf175097fb68ff9 Mon Sep 17 00:00:00 2001
From: Alaa Hleihel <ahleihel@redhat.com>
Date: Sun, 10 May 2020 15:03:55 -0400
Subject: [PATCH 078/312] [netdrv] net/mlx5: Tide up state_lock and vport
 enabled flag usage

Message-id: <20200510150452.10307-31-ahleihel@redhat.com>
Patchwork-id: 306654
Patchwork-instance: patchwork
O-Subject: [RHEL8.3 BZ 1789380 v2 30/87] net/mlx5: Tide up state_lock and vport enabled flag usage
Bugzilla: 1789380
RH-Acked-by: Kamal Heib <kheib@redhat.com>
RH-Acked-by: Jarod Wilson <jarod@redhat.com>
RH-Acked-by: Tony Camuso <tcamuso@redhat.com>
RH-Acked-by: Jonathan Toppins <jtoppins@redhat.com>

Bugzilla: http://bugzilla.redhat.com/1789380
Upstream: v5.5-rc1

commit 77b094305b1ba23e716bb34d3e33c8fe30a5f487
Author: Parav Pandit <parav@mellanox.com>
Date:   Mon Oct 28 23:35:13 2019 +0000

    net/mlx5: Tide up state_lock and vport enabled flag usage

    When eswitch is disabled, vport event handler is unregistered.
    This unregistration already synchronizes with running EQ event handler
    in below code flow.

    mlx5_eswitch_disable()
      mlx5_eswitch_event_handlers_unregister()
        mlx5_eq_notifier_unregister()
          atomic_notifier_chain_unregister()
            synchronize_rcu()

    notifier_callchain
      eswitch_vport_event()
        queue_work()

    Additionally vport->enabled flag is set under state_lock during
    esw_enable_vport() but is not read under state_lock in
    (a) esw_disable_vport() and (b) under atomic context
    eswitch_vport_event().

    It is also necessary to synchronize with already scheduled vport event.
    This is already achieved using below sequence.

    mlx5_eswitch_event_handlers_unregister()
      [..]
      flush_workqueue()

    Hence,
    (a) Remove vport->enabled check in eswitch_vport_event() which
    doesn't make any sense.
    (b) Remove redundant flush_workqueue() on every vport disable.
    (c) Keep esw_disable_vport() symmetric with esw_enable_vport() for
    state_lock.

    Signed-off-by: Parav Pandit <parav@mellanox.com>
    Reviewed-by: Vu Pham <vuhuong@mellanox.com>
    Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

Signed-off-by: Alaa Hleihel <ahleihel@redhat.com>
Signed-off-by: Frantisek Hrbata <fhrbata@redhat.com>
---
 drivers/net/ethernet/mellanox/mlx5/core/eswitch.c | 14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/eswitch.c b/drivers/net/ethernet/mellanox/mlx5/core/eswitch.c
index 54b5f290ab9d..8067667fd59e 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/eswitch.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/eswitch.c
@@ -1745,18 +1745,16 @@ static void esw_disable_vport(struct mlx5_eswitch *esw,
 {
 	u16 vport_num = vport->vport;
 
+	mutex_lock(&esw->state_lock);
 	if (!vport->enabled)
-		return;
+		goto done;
 
 	esw_debug(esw->dev, "Disabling vport(%d)\n", vport_num);
 	/* Mark this vport as disabled to discard new events */
 	vport->enabled = false;
 
-	/* Wait for current already scheduled events to complete */
-	flush_workqueue(esw->work_queue);
 	/* Disable events from this vport */
 	arm_vport_context_events_cmd(esw->dev, vport->vport, 0);
-	mutex_lock(&esw->state_lock);
 	/* We don't assume VFs will cleanup after themselves.
 	 * Calling vport change handler while vport is disabled will cleanup
 	 * the vport resources.
@@ -1775,6 +1773,8 @@ static void esw_disable_vport(struct mlx5_eswitch *esw,
 		esw_legacy_vport_destroy_drop_counters(vport);
 	}
 	esw->enabled_vports--;
+
+done:
 	mutex_unlock(&esw->state_lock);
 }
 
@@ -1788,12 +1788,8 @@ static int eswitch_vport_event(struct notifier_block *nb,
 
 	vport_num = be16_to_cpu(eqe->data.vport_change.vport_num);
 	vport = mlx5_eswitch_get_vport(esw, vport_num);
-	if (IS_ERR(vport))
-		return NOTIFY_OK;
-
-	if (vport->enabled)
+	if (!IS_ERR(vport))
 		queue_work(esw->work_queue, &vport->vport_change_handler);
-
 	return NOTIFY_OK;
 }
 
-- 
2.13.6