All of lore.kernel.org
 help / color / mirror / Atom feed
From: Mao Wenan <wenan.mao@linux.alibaba.com>
To: mst@redhat.com, jasowang@redhat.com, davem@davemloft.net,
	kuba@kernel.org
Cc: netdev@vger.kernel.org, Mao Wenan <wenan.mao@linux.alibaba.com>
Subject: [PATCH -next] virtio_net: Avoid loop in virtnet_poll
Date: Sun,  2 Aug 2020 11:41:23 +0800	[thread overview]
Message-ID: <1596339683-117617-1-git-send-email-wenan.mao@linux.alibaba.com> (raw)

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 <wenan.mao@linux.alibaba.com>
---
 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);
-- 
1.8.3.1


             reply	other threads:[~2020-08-02  3:42 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-02  3:41 Mao Wenan [this message]
2020-08-02  4:40 ` [PATCH -next] virtio_net: Avoid loop in virtnet_poll Michael S. Tsirkin
2020-08-02  5:56   ` [PATCH -next v2] " Mao Wenan
2020-08-02  5:56     ` Mao Wenan
2020-08-02  6:25     ` Michael S. Tsirkin
2020-08-02  6:25       ` Michael S. Tsirkin
2020-08-02  6:25       ` Michael S. Tsirkin
2020-08-02  6:26     ` Michael S. Tsirkin
2020-08-02  6:26       ` Michael S. Tsirkin
2020-08-02  6:26       ` Michael S. Tsirkin
2020-08-02  7:31       ` maowenan
2020-08-02  7:31         ` maowenan
2020-08-02  7:44       ` [PATCH -next v3] virtio_ring: Avoid loop when vq is broken in virtqueue_poll Mao Wenan
2020-08-02  7:44         ` Mao Wenan
2020-08-04  2:42         ` Jason Wang
2020-08-04  2:42           ` Jason Wang
2020-08-04  2:42           ` Jason Wang

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1596339683-117617-1-git-send-email-wenan.mao@linux.alibaba.com \
    --to=wenan.mao@linux.alibaba.com \
    --cc=davem@davemloft.net \
    --cc=jasowang@redhat.com \
    --cc=kuba@kernel.org \
    --cc=mst@redhat.com \
    --cc=netdev@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.