On 4/2/25 12:42, Bui Quang Minh wrote:
When setting up XDP for a running interface, we call napi_disable() on
the receive queue's napi. In delayed refill_work, it also calls
napi_disable() on the receive queue's napi. This can leads to deadlock
when napi_disable() is called on an already disabled napi. This commit
fixes this by disabling future and cancelling all inflight delayed
refill works before calling napi_disabled() in virtnet_xdp_set.
Fixes: 4941d472bf95 ("virtio-net: do not reset during XDP set")
Signed-off-by: Bui Quang Minh <minhquangbui99@xxxxxxxxx>
---
drivers/net/virtio_net.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 7e4617216a4b..33406d59efe2 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -5956,6 +5956,15 @@ static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog,
if (!prog && !old_prog)
return 0;
+ /*
+ * Make sure refill_work does not run concurrently to
+ * avoid napi_disable race which leads to deadlock.
+ */
+ if (netif_running(dev)) {
+ disable_delayed_refill(vi);
+ cancel_delayed_work_sync(&vi->refill);
+ }
+
if (prog)
bpf_prog_add(prog, vi->max_queue_pairs - 1);
@@ -6004,6 +6013,8 @@ static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog,
virtnet_napi_tx_enable(&vi->sq[i]);
}
}
+ if (netif_running(dev))
+ enable_delayed_refill(vi);
While doing some testing, it look likes that we must call try_fill_recv
to resume the rx path. I'll do more testing and send a new v2 patch.
return 0;
@@ -6019,6 +6030,7 @@ static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog,
virtnet_napi_enable(&vi->rq[i]);
virtnet_napi_tx_enable(&vi->sq[i]);
}
+ enable_delayed_refill(vi);
}
if (prog)
bpf_prog_sub(prog, vi->max_queue_pairs - 1);
