From: Longjun Tang <[email protected]>
When busy-poll is active, napi_schedule_prep() returns false in
virtqueue_napi_schedule(), so virtqueue_disable_cb() is skipped.
The device may keep firing irqs until reaches virtqueue_napi_complete().
Under load (received == budget), it will lead to a large number
of spurious interrupts.
Fix it by disabling the callback at the virtnet_poll() entry. This keeps
the callback off while we poll and re-enable by virtqueue_napi_complete()
when going idle.
Fixes: ceef438d613f ("virtio_net: remove custom busy_poll")
Acked-by: Michael S. Tsirkin <[email protected]>
Signed-off-by: Longjun Tang <[email protected]>
---
V1 -> V2: Remain agnostic to busy polling
V2 -> V3: Add fixes tag
---
drivers/net/virtio_net.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index f4adcfee7a80..0a11f2b32500 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -3008,6 +3008,11 @@ static int virtnet_poll(struct napi_struct *napi, int
budget)
unsigned int xdp_xmit = 0;
bool napi_complete;
+ /* Keep callbacks suppressed for the duration of this poll,
+ * busy-poll need.
+ */
+ virtqueue_disable_cb(rq->vq);
+
virtnet_poll_cleantx(rq, budget);
received = virtnet_receive(rq, budget, &xdp_xmit);
--
2.43.0
