[PATCH 5.15/6.1/6.6 1/2] net: ipv6: Make udp_tunnel6_xmit_skb() void

[PATCH 5.15/6.1/6.6 1/2] net: ipv6: Make udp_tunnel6_xmit_skb() void

[Alexander Martyniuk]

From: Petr Machata <petrm@nvidia.com>

commit 6a7d88ca15f73c5c570c372238f71d63da1fda55 upstream.

The function always returns zero, thus the return value does not carry any
signal. Just make it void.

Most callers already ignore the return value. However:

- Refold arguments of the call from sctp_v6_xmit() so that they fit into
  the 80-column limit.

- tipc_udp_xmit() initializes err from the return value, but that should
  already be always zero at that point. So there's no practical change, but
  elision of the assignment prompts a couple more tweaks to clean up the
  function.

Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>
Link: https://patch.msgid.link/7facacf9d8ca3ca9391a4aee88160913671b868d.1750113335.git.petrm@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Alexander Martyniuk <alexevgmart@gmail.com>
---
 include/net/udp_tunnel.h  |  2 +-
 net/ipv6/ip6_udp_tunnel.c |  3 +--
 net/sctp/ipv6.c           |  7 ++++---
 net/tipc/udp_media.c      | 10 +++++-----
 4 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/include/net/udp_tunnel.h b/include/net/udp_tunnel.h
index 6818a59a1ebc..dc796ddd231d 100644
--- a/include/net/udp_tunnel.h
+++ b/include/net/udp_tunnel.h
@@ -152,7 +152,7 @@ void udp_tunnel_xmit_skb(struct rtable *rt, struct sock *sk, struct sk_buff *skb
 			 __be16 df, __be16 src_port, __be16 dst_port,
 			 bool xnet, bool nocheck);
 
-int udp_tunnel6_xmit_skb(struct dst_entry *dst, struct sock *sk,
+void udp_tunnel6_xmit_skb(struct dst_entry *dst, struct sock *sk,
 			 struct sk_buff *skb,
 			 struct net_device *dev, struct in6_addr *saddr,
 			 struct in6_addr *daddr,
diff --git a/net/ipv6/ip6_udp_tunnel.c b/net/ipv6/ip6_udp_tunnel.c
index 7aef559e60ec..886c42de0566 100644
--- a/net/ipv6/ip6_udp_tunnel.c
+++ b/net/ipv6/ip6_udp_tunnel.c
@@ -74,7 +74,7 @@ int udp_sock_create6(struct net *net, struct udp_port_cfg *cfg,
 }
 EXPORT_SYMBOL_GPL(udp_sock_create6);
 
-int udp_tunnel6_xmit_skb(struct dst_entry *dst, struct sock *sk,
+void udp_tunnel6_xmit_skb(struct dst_entry *dst, struct sock *sk,
 			 struct sk_buff *skb,
 			 struct net_device *dev, struct in6_addr *saddr,
 			 struct in6_addr *daddr,
@@ -108,7 +108,6 @@ int udp_tunnel6_xmit_skb(struct dst_entry *dst, struct sock *sk,
 	ip6h->saddr	  = *saddr;
 
 	ip6tunnel_xmit(sk, skb, dev);
-	return 0;
 }
 EXPORT_SYMBOL_GPL(udp_tunnel6_xmit_skb);
 
diff --git a/net/sctp/ipv6.c b/net/sctp/ipv6.c
index 0673857cb3d8..12469cf1a49d 100644
--- a/net/sctp/ipv6.c
+++ b/net/sctp/ipv6.c
@@ -263,9 +263,10 @@ static int sctp_v6_xmit(struct sk_buff *skb, struct sctp_transport *t)
 	skb_set_inner_ipproto(skb, IPPROTO_SCTP);
 	label = ip6_make_flowlabel(sock_net(sk), skb, fl6->flowlabel, true, fl6);
 
-	return udp_tunnel6_xmit_skb(dst, sk, skb, NULL, &fl6->saddr,
-				    &fl6->daddr, tclass, ip6_dst_hoplimit(dst),
-				    label, sctp_sk(sk)->udp_port, t->encap_port, false);
+	udp_tunnel6_xmit_skb(dst, sk, skb, NULL, &fl6->saddr, &fl6->daddr,
+			     tclass, ip6_dst_hoplimit(dst), label,
+			     sctp_sk(sk)->udp_port, t->encap_port, false);
+	return 0;
 }
 
 /* Returns the dst cache entry for the given source and destination ip
diff --git a/net/tipc/udp_media.c b/net/tipc/udp_media.c
index e993bd6ed7c2..26aca3df2978 100644
--- a/net/tipc/udp_media.c
+++ b/net/tipc/udp_media.c
@@ -172,7 +172,7 @@ static int tipc_udp_xmit(struct net *net, struct sk_buff *skb,
 			 struct udp_media_addr *dst, struct dst_cache *cache)
 {
 	struct dst_entry *ndst;
-	int ttl, err = 0;
+	int ttl, err;
 
 	local_bh_disable();
 	ndst = dst_cache_get(cache);
@@ -217,13 +217,13 @@ static int tipc_udp_xmit(struct net *net, struct sk_buff *skb,
 			dst_cache_set_ip6(cache, ndst, &fl6.saddr);
 		}
 		ttl = ip6_dst_hoplimit(ndst);
-		err = udp_tunnel6_xmit_skb(ndst, ub->ubsock->sk, skb, NULL,
-					   &src->ipv6, &dst->ipv6, 0, ttl, 0,
-					   src->port, dst->port, false);
+		udp_tunnel6_xmit_skb(ndst, ub->ubsock->sk, skb, NULL,
+				     &src->ipv6, &dst->ipv6, 0, ttl, 0,
+				     src->port, dst->port, false);
 #endif
 	}
 	local_bh_enable();
-	return err;
+	return 0;
 
 tx_error:
 	local_bh_enable();
-- 
2.43.0

[PATCH 5.15/6.1/6.6 2/2] sctp: disable BH before calling udp_tunnel_xmit_skb()

[Alexander Martyniuk]

From: Xin Long <lucien.xin@gmail.com>

commit 2cd7e6971fc2787408ceef17906ea152791448cf upstream.

udp_tunnel_xmit_skb() / udp_tunnel6_xmit_skb() are expected to run with
BH disabled.  After commit 6f1a9140ecda ("add xmit recursion limit to
tunnel xmit functions"), on the path:

  udp(6)_tunnel_xmit_skb() -> ip(6)tunnel_xmit()

dev_xmit_recursion_inc()/dec() must stay balanced on the same CPU.

Without local_bh_disable(), the context may move between CPUs, which can
break the inc/dec pairing. This may lead to incorrect recursion level
detection and cause packets to be dropped in ip(6)_tunnel_xmit() or
__dev_queue_xmit().

Fix it by disabling BH around both IPv4 and IPv6 SCTP UDP xmit paths.

In my testing, after enabling the SCTP over UDP:

  # ip net exec ha sysctl -w net.sctp.udp_port=9899
  # ip net exec ha sysctl -w net.sctp.encap_port=9899
  # ip net exec hb sysctl -w net.sctp.udp_port=9899
  # ip net exec hb sysctl -w net.sctp.encap_port=9899

  # ip net exec ha iperf3 -s

- without this patch:

  # ip net exec hb iperf3 -c 192.168.0.1 --sctp
  [  5]   0.00-10.00  sec  37.2 MBytes  31.2 Mbits/sec  sender
  [  5]   0.00-10.00  sec  37.1 MBytes  31.1 Mbits/sec  receiver

- with this patch:

  # ip net exec hb iperf3 -c 192.168.0.1 --sctp
  [  5]   0.00-10.00  sec  3.14 GBytes  2.69 Gbits/sec  sender
  [  5]   0.00-10.00  sec  3.14 GBytes  2.69 Gbits/sec  receiver

Fixes: 6f1a9140ecda ("net: add xmit recursion limit to tunnel xmit functions")
Fixes: 046c052b475e ("sctp: enable udp tunneling socks")
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Link: https://patch.msgid.link/c874a8548221dcd56ff03c65ba75a74e6cf99119.1776017727.git.lucien.xin@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Alexander Martyniuk <alexevgmart@gmail.com>
---
 net/sctp/ipv6.c     | 2 ++
 net/sctp/protocol.c | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/net/sctp/ipv6.c b/net/sctp/ipv6.c
index 12469cf1a49d..99686b87b99a 100644
--- a/net/sctp/ipv6.c
+++ b/net/sctp/ipv6.c
@@ -263,9 +263,11 @@ static int sctp_v6_xmit(struct sk_buff *skb, struct sctp_transport *t)
 	skb_set_inner_ipproto(skb, IPPROTO_SCTP);
 	label = ip6_make_flowlabel(sock_net(sk), skb, fl6->flowlabel, true, fl6);
 
+	local_bh_disable();
 	udp_tunnel6_xmit_skb(dst, sk, skb, NULL, &fl6->saddr, &fl6->daddr,
 			     tclass, ip6_dst_hoplimit(dst), label,
 			     sctp_sk(sk)->udp_port, t->encap_port, false);
+	local_bh_enable();
 	return 0;
 }
 
diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c
index 2185f44198de..0f7e241178f5 100644
--- a/net/sctp/protocol.c
+++ b/net/sctp/protocol.c
@@ -1085,9 +1085,11 @@ static inline int sctp_v4_xmit(struct sk_buff *skb, struct sctp_transport *t)
 	skb_reset_inner_mac_header(skb);
 	skb_reset_inner_transport_header(skb);
 	skb_set_inner_ipproto(skb, IPPROTO_SCTP);
+	local_bh_disable();
 	udp_tunnel_xmit_skb((struct rtable *)dst, sk, skb, fl4->saddr,
 			    fl4->daddr, dscp, ip4_dst_hoplimit(dst), df,
 			    sctp_sk(sk)->udp_port, t->encap_port, false, false);
+	local_bh_enable();
 	return 0;
 }
 
-- 
2.43.0