[PATCH -next] virtio_net: Avoid loop in virtnet_poll
From: Mao Wenan <hidden>
Date: 2020-08-02 03:42:25
Subsystem:
networking drivers, the rest, virtio net driver · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds, "Michael S. Tsirkin", Jason Wang, Eugenio Pérez
The loop may exist if vq->broken is true, virtqueue_get_buf_ctx_packed or virtqueue_get_buf_ctx_split will return NULL, so virtnet_poll will reschedule napi to receive packet, it will lead cpu usage(si) to 100%. call trace as below: virtnet_poll virtnet_receive virtqueue_get_buf_ctx virtqueue_get_buf_ctx_packed virtqueue_get_buf_ctx_split virtqueue_napi_complete virtqueue_napi_schedule //it will reschedule napi Signed-off-by: Mao Wenan <redacted> --- drivers/net/virtio_net.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index ba38765..a058da1 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c@@ -327,7 +327,8 @@ static void virtqueue_napi_complete(struct napi_struct *napi, opaque = virtqueue_enable_cb_prepare(vq); if (napi_complete_done(napi, processed)) { - if (unlikely(virtqueue_poll(vq, opaque))) + if (unlikely(virtqueue_poll(vq, opaque)) && + unlikely(!virtqueue_is_broken(vq))) virtqueue_napi_schedule(napi, vq); } else { virtqueue_disable_cb(vq);
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1.8.3.1