1 files changed, 32 insertions, 6 deletions

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 73e6854ea662..6376ad915765 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -3110,10 +3110,38 @@ static void __net_exit tcp_sk_exit(struct net *net)
 			       net->ipv4.tcp_congestion_control->owner);
 }
 
-static int __net_init tcp_sk_init(struct net *net)
+static void __net_init tcp_set_hashinfo(struct net *net)
 {
-	int cnt;
+	struct inet_hashinfo *hinfo;
+	unsigned int ehash_entries;
+	struct net *old_net;
+
+	if (net_eq(net, &init_net))
+		goto fallback;
+
+	old_net = current->nsproxy->net_ns;
+	ehash_entries = READ_ONCE(old_net->ipv4.sysctl_tcp_child_ehash_entries);
+	if (!ehash_entries)
+		goto fallback;
+
+	ehash_entries = roundup_pow_of_two(ehash_entries);
+	hinfo = inet_pernet_hashinfo_alloc(&tcp_hashinfo, ehash_entries);
+	if (!hinfo) {
+		pr_warn("Failed to allocate TCP ehash (entries: %u) "
+			"for a netns, fallback to the global one\n",
+			ehash_entries);
+fallback:
+		hinfo = &tcp_hashinfo;
+		ehash_entries = tcp_hashinfo.ehash_mask + 1;
+	}
+
+	net->ipv4.tcp_death_row.hashinfo = hinfo;
+	net->ipv4.tcp_death_row.sysctl_max_tw_buckets = ehash_entries / 2;
+	net->ipv4.sysctl_max_syn_backlog = max(128U, ehash_entries / 128);
+}
 
+static int __net_init tcp_sk_init(struct net *net)
+{
 	net->ipv4.sysctl_tcp_ecn = 2;
 	net->ipv4.sysctl_tcp_ecn_fallback = 1;
 
@@ -3140,11 +3168,8 @@ static int __net_init tcp_sk_init(struct net *net)
 	net->ipv4.sysctl_tcp_no_ssthresh_metrics_save = 1;
 
 	refcount_set(&net->ipv4.tcp_death_row.tw_refcount, 1);
-	cnt = tcp_hashinfo.ehash_mask + 1;
-	net->ipv4.tcp_death_row.sysctl_max_tw_buckets = cnt / 2;
-	net->ipv4.tcp_death_row.hashinfo = &tcp_hashinfo;
+	tcp_set_hashinfo(net);
 
-	net->ipv4.sysctl_max_syn_backlog = max(128, cnt / 128);
 	net->ipv4.sysctl_tcp_sack = 1;
 	net->ipv4.sysctl_tcp_window_scaling = 1;
 	net->ipv4.sysctl_tcp_timestamps = 1;
@@ -3209,6 +3234,7 @@ static void __net_exit tcp_sk_exit_batch(struct list_head *net_exit_list)
 	tcp_twsk_purge(net_exit_list, AF_INET);
 
 	list_for_each_entry(net, net_exit_list, exit_list) {
+		inet_pernet_hashinfo_free(net->ipv4.tcp_death_row.hashinfo);
 		WARN_ON_ONCE(!refcount_dec_and_test(&net->ipv4.tcp_death_row.tw_refcount));
 		tcp_fastopen_ctx_destroy(net);
 	}