On 4/29/25 21:31, Jakub Kicinski wrote:
Commit 4bc12818b363 ("virtio-net: disable delayed refill when pausing rx") fixed a deadlock between reconfig paths and refill work trying to disable the same NAPI instance. The refill work can't run in parallel with reconfig because trying to double-disable a NAPI instance causes a stall under the instance lock, which the reconfig path needs to re-enable the NAPI and therefore unblock the stalled thread.There are two cases where we re-enable refill too early. One is in the virtnet_set_queues() handler. We call it when installing XDP: virtnet_rx_pause_all(vi); ... virtnet_napi_tx_disable(..); ... virtnet_set_queues(..); ... virtnet_rx_resume_all(..); We want the work to be disabled until we call virtnet_rx_resume_all(), but virtnet_set_queues() kicks it before NAPIs were re-enabled. The other case is a more trivial case of mis-ordering in __virtnet_rx_resume() found by code inspection. Fixes: 4bc12818b363 ("virtio-net: disable delayed refill when pausing rx") Fixes: 413f0271f396 ("net: protect NAPI enablement with netdev_lock()") Signed-off-by: Jakub Kicinski <k...@kernel.org> --- CC: m...@redhat.com CC: jasow...@redhat.com CC: xuanz...@linux.alibaba.com CC: epere...@redhat.com CC: minhquangbu...@gmail.com CC: rom...@fr.zoreil.com CC: kun...@amazon.com CC: virtualizat...@lists.linux.dev --- drivers/net/virtio_net.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 848fab51dfa1..4c904e176495 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -3383,12 +3383,15 @@ static void __virtnet_rx_resume(struct virtnet_info *vi, bool refill) { bool running = netif_running(vi->dev); + bool schedule_refill = false;if (refill && !try_fill_recv(vi, rq, GFP_KERNEL))- schedule_delayed_work(&vi->refill, 0); - + 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)@@ -3728,7 +3731,7 @@ static int virtnet_set_queues(struct virtnet_info *vi, u16 queue_pairs) succ: vi->curr_queue_pairs = queue_pairs; /* virtnet_open() will refill when device is going to up. */ - if (dev->flags & IFF_UP) + if (dev->flags & IFF_UP && vi->refill_enabled) schedule_delayed_work(&vi->refill, 0);return 0;
Reviewed-by: Bui Quang Minh <minhquangbu...@gmail.com> Thanks, Quang Minh.
