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Subject[PATCH 6/7] vdpa/mlx5: Avoid using reslock in event_handler
Date
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>
---
drivers/vdpa/mlx5/net/mlx5_vnet.c | 14 +++-----------
1 file changed, 3 insertions(+), 11 deletions(-)

diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
index 6e6490c85be2..bebfba530247 100644
--- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
+++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
@@ -2872,8 +2872,8 @@ 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];
@@ -3051,7 +3051,7 @@ 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);
@@ -3068,21 +3068,13 @@ 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:
--
2.38.1
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