[PATCH 1/2] virtio_net: disable cb when in busy-polling

[Longjun Tang <lange_tang@163.com>]

From: Longjun Tang <tanglongjun@kylinos.cn>

virtnet_poll() is shared between NAPI softirq context and the busy-poll
path (sk_busy_loop).  In the busy-poll path the caller drives the loop
directly and does not rely on interrupts to schedule NAPI; keeping
callbacks enabled is wasteful and risks a flood of IRQ_NONE returns that
can trigger the kernel's spurious-IRQ detector.

Signed-off-by: Longjun Tang <tanglongjun@kylinos.cn>
---
 drivers/net/virtio_net.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 72d6a9c6a5a2..df365fba2c40 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -3078,6 +3078,9 @@ static int virtnet_poll(struct napi_struct *napi, int budget)
 	unsigned int xdp_xmit = 0;
 	bool napi_complete;
 
+	if (READ_ONCE(napi->state) & NAPIF_STATE_IN_BUSY_POLL)
+		virtqueue_disable_cb(rq->vq);
+
 	virtnet_poll_cleantx(rq, budget);
 
 	received = virtnet_receive(rq, budget, &xdp_xmit);
-- 
2.43.0