virtio_net: suppress cpu stall when free_unused_bufs

[ Upstream commit f8bb5104394560e29017c25bcade4c6b7aabd108 ]

For multi-queue and large ring-size use case, the following error
occurred when free_unused_bufs:
rcu: INFO: rcu_sched self-detected stall on CPU.

Fixes: 986a4f4d452d ("virtio_net: multiqueue support")
Signed-off-by: Wenliang Wang <wangwenliang.1995@bytedance.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index cff3e2a7ce7fce368307c49203e39a6856a73506..9f2d691908b42cacb3c12e465567e3b02f363fec 100644 (file)
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -2844,12 +2844,14 @@ static void free_unused_bufs(struct virtnet_info *vi)
                struct virtqueue *vq = vi->sq[i].vq;
                while ((buf = virtqueue_detach_unused_buf(vq)) != NULL)
                        virtnet_sq_free_unused_buf(vq, buf);
+               cond_resched();
        }
 
        for (i = 0; i < vi->max_queue_pairs; i++) {
                struct virtqueue *vq = vi->rq[i].vq;
                while ((buf = virtqueue_detach_unused_buf(vq)) != NULL)
                        virtnet_rq_free_unused_buf(vq, buf);
+               cond_resched();
        }
 }