[PATCH net 4/4] netfilter: conntrack: warn when cleanup is stuck

[Jakub Kicinski <kuba@kernel.org>]

nf_conntrack_cleanup_net_list() calls schedule() so it does not
show up as a hung task. Add an explicit check to make debugging
leaked skbs/conntack references more obvious.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
 net/netfilter/nf_conntrack_core.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index 0b95f226f211..d1f8eb725d42 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -2487,6 +2487,7 @@ void nf_conntrack_cleanup_net(struct net *net)
 void nf_conntrack_cleanup_net_list(struct list_head *net_exit_list)
 {
 	struct nf_ct_iter_data iter_data = {};
+	unsigned long start = jiffies;
 	struct net *net;
 	int busy;
 
@@ -2507,6 +2508,8 @@ void nf_conntrack_cleanup_net_list(struct list_head *net_exit_list)
 			busy = 1;
 	}
 	if (busy) {
+		DEBUG_NET_WARN_ONCE(time_after(jiffies, start + 60 * HZ),
+				    "conntrack cleanup blocked for 60s");
 		schedule();
 		goto i_see_dead_people;
 	}
-- 
2.52.0