[PATCH 4.19 36/86] ipvs: fix the connection sync failed in some cases

Greg Kroah-Hartman
2020-07-27T14:38:09Z

From: guodeqing <geffrey.guo@huawei.com>

[ Upstream commit 8210e344ccb798c672ab237b1a4f241bda08909b ]

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.

Here I add the check of whether the reader_queue of the udp sock is
empty or not to solve this problem.

Fixes: 2276f58ac589 ("udp: use a separate rx queue for packet reception")
Reported-by: zhouxudong <zhouxudong8@huawei.com>
Signed-off-by: guodeqing <geffrey.guo@huawei.com>
Acked-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 5acd99f83166b..f6af13c16cf57 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_lockless(&sk->sk_receive_queue) ||
+ !skb_queue_empty_lockless(&up->reader_queue) ||
+ kthread_should_stop());

/* do we have data now? */
- while (!skb_queue_empty(&(tinfo->sock->sk->sk_receive_queue))) {
+ while (!skb_queue_empty_lockless(&sk->sk_receive_queue) ||
+ !skb_queue_empty_lockless(&up->reader_queue)) {
len = ip_vs_receive(tinfo->sock, tinfo->buf,
ipvs->bcfg.sync_maxlen);
if (len <= 0) {
--
2.25.1