vdpa/mlx5: Avoid using reslock in event_handler

[ Upstream commit 0dbc1b4ae07d003b2e88ba9d4142846320f8e349 ]

event_handler runs under atomic context and may not acquire reslock. We
can still guarantee that the handler won't be called after suspend by
clearing nb_registered, unregistering the handler and flushing the
workqueue.

Signed-off-by: Eli Cohen <elic@nvidia.com>
Message-Id: <20221114131759.57883-5-elic@nvidia.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
index b06260a..98dd8ce 100644 (file)
--- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
+++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
@@ -2845,8 +2845,8 @@ static int mlx5_vdpa_suspend(struct vdpa_device *vdev)
        int i;
 
        down_write(&ndev->reslock);
-       mlx5_notifier_unregister(mvdev->mdev, &ndev->nb);
        ndev->nb_registered = false;
+       mlx5_notifier_unregister(mvdev->mdev, &ndev->nb);
        flush_workqueue(ndev->mvdev.wq);
        for (i = 0; i < ndev->cur_num_vqs; i++) {
                mvq = &ndev->vqs[i];
@@ -3024,7 +3024,7 @@ static void update_carrier(struct work_struct *work)
        else
                ndev->config.status &= cpu_to_mlx5vdpa16(mvdev, ~VIRTIO_NET_S_LINK_UP);
 
-       if (ndev->config_cb.callback)
+       if (ndev->nb_registered && ndev->config_cb.callback)
                ndev->config_cb.callback(ndev->config_cb.private);
 
        kfree(wqent);
@@ -3041,21 +3041,13 @@ static int event_handler(struct notifier_block *nb, unsigned long event, void *p
                switch (eqe->sub_type) {
                case MLX5_PORT_CHANGE_SUBTYPE_DOWN:
                case MLX5_PORT_CHANGE_SUBTYPE_ACTIVE:
-                       down_read(&ndev->reslock);
-                       if (!ndev->nb_registered) {
-                               up_read(&ndev->reslock);
-                               return NOTIFY_DONE;
-                       }
                        wqent = kzalloc(sizeof(*wqent), GFP_ATOMIC);
-                       if (!wqent) {
-                               up_read(&ndev->reslock);
+                       if (!wqent)
                                return NOTIFY_DONE;
-                       }
 
                        wqent->mvdev = &ndev->mvdev;
                        INIT_WORK(&wqent->work, update_carrier);
                        queue_work(ndev->mvdev.wq, &wqent->work);
-                       up_read(&ndev->reslock);
                        ret = NOTIFY_OK;
                        break;
                default:
@@ -3242,8 +3234,8 @@ static void mlx5_vdpa_dev_del(struct vdpa_mgmt_dev *v_mdev, struct vdpa_device *
        struct workqueue_struct *wq;
 
        if (ndev->nb_registered) {
-               mlx5_notifier_unregister(mvdev->mdev, &ndev->nb);
                ndev->nb_registered = false;
+               mlx5_notifier_unregister(mvdev->mdev, &ndev->nb);
        }
        wq = mvdev->wq;
        mvdev->wq = NULL;