From: Wenliang Wang <wangwenliang.1995@bytedance.com>
Date: Thu, 4 May 2023 10:27:06 +0800
Subject: [PATCH] virtio_net: suppress cpu stall when free_unused_bufs
References: bsc#1012628
Patch-mainline: 6.3.3
Git-commit: f8bb5104394560e29017c25bcade4c6b7aabd108

[ 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>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 drivers/net/virtio_net.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index ea1bd4bb..744bdc8a 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -3559,12 +3559,14 @@ 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();
 	}
 }
 
-- 
2.35.3