Calling napi_disable() on an already disabled napi can cause the deadlock. Because the delayed refill work will call napi_disable(), we must ensure that refill work is only enabled and scheduled after we have enabled the rx queue's NAPI.
Signed-off-by: Bui Quang Minh <[email protected]> --- drivers/net/virtio_net.c | 31 ++++++++++++++++++++++++------- 1 file changed, 24 insertions(+), 7 deletions(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 63126e490bda..8016d2b378cf 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -3208,16 +3208,31 @@ static int virtnet_open(struct net_device *dev) int i, err; for (i = 0; i < vi->max_queue_pairs; i++) { + bool schedule_refill = false; + + /* - We must call try_fill_recv before enabling napi of the same + * receive queue so that it doesn't race with the call in + * virtnet_receive. + * - We must enable and schedule delayed refill work only when + * we have enabled all the receive queue's napi. Otherwise, in + * refill_work, we have a deadlock when calling napi_disable on + * an already disabled napi. + */ if (i < vi->curr_queue_pairs) { - enable_delayed_refill(&vi->rq[i]); /* Make sure we have some buffers: if oom use wq. */ if (!try_fill_recv(vi, &vi->rq[i], GFP_KERNEL)) - schedule_delayed_work(&vi->rq[i].refill, 0); + schedule_refill = true; } err = virtnet_enable_queue_pair(vi, i); if (err < 0) goto err_enable_qp; + + if (i < vi->curr_queue_pairs) { + enable_delayed_refill(&vi->rq[i]); + if (schedule_refill) + schedule_delayed_work(&vi->rq[i].refill, 0); + } } if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_STATUS)) { @@ -3456,11 +3471,16 @@ static void __virtnet_rx_resume(struct virtnet_info *vi, bool running = netif_running(vi->dev); bool schedule_refill = false; + /* See the comment in virtnet_open for the ordering rule + * of try_fill_recv, receive queue napi_enable and delayed + * refill enable/schedule. + */ if (refill && !try_fill_recv(vi, rq, GFP_KERNEL)) schedule_refill = true; if (running) virtnet_napi_enable(rq); + enable_delayed_refill(rq); if (schedule_refill) schedule_delayed_work(&rq->refill, 0); } @@ -3470,18 +3490,15 @@ static void virtnet_rx_resume_all(struct virtnet_info *vi) int i; for (i = 0; i < vi->max_queue_pairs; i++) { - if (i < vi->curr_queue_pairs) { - enable_delayed_refill(&vi->rq[i]); + if (i < vi->curr_queue_pairs) __virtnet_rx_resume(vi, &vi->rq[i], true); - } else { + else __virtnet_rx_resume(vi, &vi->rq[i], false); - } } } static void virtnet_rx_resume(struct virtnet_info *vi, struct receive_queue *rq) { - enable_delayed_refill(rq); __virtnet_rx_resume(vi, rq, true); } -- 2.43.0
