Calling napi_disable() on an already disabled napi can cause the
deadlock. In commit 4bc12818b363 ("virtio-net: disable delayed refill
when pausing rx"), to avoid the deadlock, when pausing the RX in
virtnet_rx_pause[_all](), we disable and cancel the delayed refill work.
However, in the virtnet_rx_resume_all(), we enable the delayed refill
work too early before enabling all the receive queue napis.
The deadlock can be reproduced by running
selftests/drivers/net/hw/xsk_reconfig.py with multiqueue virtio-net
device and inserting a cond_resched() inside the for loop in
virtnet_rx_resume_all() to increase the success rate. Because the worker
processing the delayed refilled work runs on the same CPU as
virtnet_rx_resume_all(), a reschedule is needed to cause the deadlock.
In real scenario, the contention on netdev_lock can cause the
reschedule.
This fixes the deadlock by ensuring all receive queue's napis are
enabled before we enable the delayed refill work in
virtnet_rx_resume_all() and virtnet_open().
Fixes: 4bc12818b363 ("virtio-net: disable delayed refill when pausing rx")
Reported-by: Paolo Abeni <[email protected]>
Closes:
https://netdev-ctrl.bots.linux.dev/logs/vmksft/drv-hw-dbg/results/400961/3-xdp-py/stderr
Signed-off-by: Bui Quang Minh <[email protected]>
---
drivers/net/virtio_net.c | 59 +++++++++++++++++++---------------------
1 file changed, 28 insertions(+), 31 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 8e04adb57f52..f2b1ea65767d 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -2858,6 +2858,20 @@ static bool try_fill_recv(struct virtnet_info *vi,
struct receive_queue *rq,
return err != -ENOMEM;
}
+static void virtnet_rx_refill_all(struct virtnet_info *vi)
+{
+ bool schedule_refill = false;
+ int i;
+
+ enable_delayed_refill(vi);
+ for (i = 0; i < vi->curr_queue_pairs; i++)
+ if (!try_fill_recv(vi, &vi->rq[i], GFP_KERNEL))
+ schedule_refill = true;
+
+ if (schedule_refill)
+ schedule_delayed_work(&vi->refill, 0);
+}
+
static void skb_recv_done(struct virtqueue *rvq)
{
struct virtnet_info *vi = rvq->vdev->priv;
@@ -3216,19 +3230,14 @@ static int virtnet_open(struct net_device *dev)
struct virtnet_info *vi = netdev_priv(dev);
int i, err;
- enable_delayed_refill(vi);
-
for (i = 0; i < vi->max_queue_pairs; i++) {
- if (i < vi->curr_queue_pairs)
- /* Make sure we have some buffers: if oom use wq. */
- if (!try_fill_recv(vi, &vi->rq[i], GFP_KERNEL))
- schedule_delayed_work(&vi->refill, 0);
-
err = virtnet_enable_queue_pair(vi, i);
if (err < 0)
goto err_enable_qp;
}
+ virtnet_rx_refill_all(vi);
+
if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_STATUS)) {
if (vi->status & VIRTIO_NET_S_LINK_UP)
netif_carrier_on(vi->dev);
@@ -3463,39 +3472,27 @@ static void virtnet_rx_pause(struct virtnet_info *vi,
struct receive_queue *rq)
__virtnet_rx_pause(vi, rq);
}
-static void __virtnet_rx_resume(struct virtnet_info *vi,
- struct receive_queue *rq,
- bool refill)
-{
- bool running = netif_running(vi->dev);
- bool schedule_refill = false;
-
- if (refill && !try_fill_recv(vi, rq, GFP_KERNEL))
- schedule_refill = true;
- if (running)
- virtnet_napi_enable(rq);
-
- if (schedule_refill)
- schedule_delayed_work(&vi->refill, 0);
-}
-
static void virtnet_rx_resume_all(struct virtnet_info *vi)
{
int i;
- enable_delayed_refill(vi);
- for (i = 0; i < vi->max_queue_pairs; i++) {
- if (i < vi->curr_queue_pairs)
- __virtnet_rx_resume(vi, &vi->rq[i], true);
- else
- __virtnet_rx_resume(vi, &vi->rq[i], false);
+ if (netif_running(vi->dev)) {
+ for (i = 0; i < vi->max_queue_pairs; i++)
+ virtnet_napi_enable(&vi->rq[i]);
+
+ virtnet_rx_refill_all(vi);
}
}
static void virtnet_rx_resume(struct virtnet_info *vi, struct receive_queue
*rq)
{
- enable_delayed_refill(vi);
- __virtnet_rx_resume(vi, rq, true);
+ if (netif_running(vi->dev)) {
+ virtnet_napi_enable(rq);
+
+ enable_delayed_refill(vi);
+ if (!try_fill_recv(vi, rq, GFP_KERNEL))
+ schedule_delayed_work(&vi->refill, 0);
+ }
}
static int virtnet_rx_resize(struct virtnet_info *vi,
--
2.43.0
