Hello,
On Wed, 15 Jul 2020, guodeqing wrote:
> The sync_thread_backup only checks sk_receive_queue is empty or not,
> there is a situation which cannot sync the connection entries when
> sk_receive_queue is empty and sk_rmem_alloc is larger than sk_rcvbuf,
> the sync packets are dropped in __udp_enqueue_schedule_skb, this is
> because the packets in reader_queue is not read, so the rmem is
> not reclaimed.
Good catch. We missed this change in UDP...
> Here I add the check of whether the reader_queue of the udp sock is
> empty or not to solve this problem.
>
> Fixes: 7c13f97ffde6 ("udp: do fwd memory scheduling on dequeue")
Why this commit and not 2276f58ac589 which adds
reader_queue to udp_poll() ? May be both?
> Reported-by: zhouxudong <zhouxudong8@xxxxxxxxxx>
> Signed-off-by: guodeqing <geffrey.guo@xxxxxxxxxx>
> ---
> net/netfilter/ipvs/ip_vs_sync.c | 12 ++++++++----
> 1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/net/netfilter/ipvs/ip_vs_sync.c b/net/netfilter/ipvs/ip_vs_sync.c
> index 605e0f6..abe8d63 100644
> --- a/net/netfilter/ipvs/ip_vs_sync.c
> +++ b/net/netfilter/ipvs/ip_vs_sync.c
> @@ -1717,6 +1717,8 @@ static int sync_thread_backup(void *data)
> {
> struct ip_vs_sync_thread_data *tinfo = data;
> struct netns_ipvs *ipvs = tinfo->ipvs;
> + struct sock *sk = tinfo->sock->sk;
> + struct udp_sock *up = udp_sk(sk);
> int len;
>
> pr_info("sync thread started: state = BACKUP, mcast_ifn = %s, "
> @@ -1724,12 +1726,14 @@ static int sync_thread_backup(void *data)
> ipvs->bcfg.mcast_ifn, ipvs->bcfg.syncid, tinfo->id);
>
> while (!kthread_should_stop()) {
> - wait_event_interruptible(*sk_sleep(tinfo->sock->sk),
> - !skb_queue_empty(&tinfo->sock->sk->sk_receive_queue)
> - || kthread_should_stop());
> + wait_event_interruptible(*sk_sleep(sk),
> + !skb_queue_empty(&sk->sk_receive_queue) ||
> + !skb_queue_empty(&up->reader_queue) ||
May be we should use skb_queue_empty_lockless for 5.4+
and skb_queue_empty() for backports to 4.14 and 4.19...
> + kthread_should_stop());
>
> /* do we have data now? */
> - while (!skb_queue_empty(&(tinfo->sock->sk->sk_receive_queue))) {
> + while (!skb_queue_empty(&sk->sk_receive_queue) ||
> + !skb_queue_empty(&up->reader_queue)) {
Here too
> len = ip_vs_receive(tinfo->sock, tinfo->buf,
> ipvs->bcfg.sync_maxlen);
> if (len <= 0) {
> --
> 2.7.4
Regards
--
Julian Anastasov <ja@xxxxxx>
