[PATCH net-next] ipv4: Drop tos parameter from flowi4_update_output()

[PATCH net-next] ipv4: Drop tos parameter from flowi4_update_output()

[Guillaume Nault]

Callers of flowi4_update_output() never try to update ->flowi4_tos:

  * ip_route_connect() updates ->flowi4_tos with its own current
    value.

  * ip_route_newports() has two users: tcp_v4_connect() and
    dccp_v4_connect. Both initialise fl4 with ip_route_connect(), which
    in turn sets ->flowi4_tos with RT_TOS(inet_sk(sk)->tos) and
    ->flowi4_scope based on SOCK_LOCALROUTE.

    Then ip_route_newports() updates ->flowi4_tos with
    RT_CONN_FLAGS(sk), which is the same as RT_TOS(inet_sk(sk)->tos),
    unless SOCK_LOCALROUTE is set on the socket. In that case, the
    lowest order bit is set to 1, to eventually inform
    ip_route_output_key_hash() to restrict the scope to RT_SCOPE_LINK.
    This is equivalent to properly setting ->flowi4_scope as
    ip_route_connect() did.

  * ip_vs_xmit.c initialises ->flowi4_tos with memset(0), then calls
    flowi4_update_output() with tos=0.

  * sctp_v4_get_dst() uses the same RT_CONN_FLAGS_TOS() when
    initialising ->flowi4_tos and when calling flowi4_update_output().

In the end, ->flowi4_tos never changes. So let's just drop the tos
parameter. This will simplify the conversion of ->flowi4_tos from __u8
to dscp_t.

Signed-off-by: Guillaume Nault <gnault@redhat.com>
---
Looks like oif could be removed too.
---
 include/net/flow.h              | 3 +--
 include/net/route.h             | 6 ++----
 net/netfilter/ipvs/ip_vs_xmit.c | 4 ++--
 net/sctp/protocol.c             | 4 +---
 4 files changed, 6 insertions(+), 11 deletions(-)

diff --git a/include/net/flow.h b/include/net/flow.h
index bb8651a6eaa7..7f0adda3bf2f 100644
--- a/include/net/flow.h
+++ b/include/net/flow.h
@@ -116,11 +116,10 @@ static inline void flowi4_init_output(struct flowi4 *fl4, int oif,
 }
 
 /* Reset some input parameters after previous lookup */
-static inline void flowi4_update_output(struct flowi4 *fl4, int oif, __u8 tos,
+static inline void flowi4_update_output(struct flowi4 *fl4, int oif,
 					__be32 daddr, __be32 saddr)
 {
 	fl4->flowi4_oif = oif;
-	fl4->flowi4_tos = tos;
 	fl4->daddr = daddr;
 	fl4->saddr = saddr;
 }
diff --git a/include/net/route.h b/include/net/route.h
index bcc367cf3aa2..5a5c726472bd 100644
--- a/include/net/route.h
+++ b/include/net/route.h
@@ -321,8 +321,7 @@ static inline struct rtable *ip_route_connect(struct flowi4 *fl4, __be32 dst,
 		if (IS_ERR(rt))
 			return rt;
 		ip_rt_put(rt);
-		flowi4_update_output(fl4, oif, fl4->flowi4_tos, fl4->daddr,
-				     fl4->saddr);
+		flowi4_update_output(fl4, oif, fl4->daddr, fl4->saddr);
 	}
 	security_sk_classify_flow(sk, flowi4_to_flowi_common(fl4));
 	return ip_route_output_flow(net, fl4, sk);
@@ -337,8 +336,7 @@ static inline struct rtable *ip_route_newports(struct flowi4 *fl4, struct rtable
 		fl4->fl4_dport = dport;
 		fl4->fl4_sport = sport;
 		ip_rt_put(rt);
-		flowi4_update_output(fl4, sk->sk_bound_dev_if,
-				     RT_CONN_FLAGS(sk), fl4->daddr,
+		flowi4_update_output(fl4, sk->sk_bound_dev_if, fl4->daddr,
 				     fl4->saddr);
 		security_sk_classify_flow(sk, flowi4_to_flowi_common(fl4));
 		return ip_route_output_flow(sock_net(sk), fl4, sk);
diff --git a/net/netfilter/ipvs/ip_vs_xmit.c b/net/netfilter/ipvs/ip_vs_xmit.c
index feb1d7fcb09f..c7652da78c88 100644
--- a/net/netfilter/ipvs/ip_vs_xmit.c
+++ b/net/netfilter/ipvs/ip_vs_xmit.c
@@ -139,7 +139,7 @@ static struct rtable *do_output_route4(struct net *net, __be32 daddr,
 		if (PTR_ERR(rt) == -EINVAL && *saddr &&
 		    rt_mode & IP_VS_RT_MODE_CONNECT && !loop) {
 			*saddr = 0;
-			flowi4_update_output(&fl4, 0, 0, daddr, 0);
+			flowi4_update_output(&fl4, 0, daddr, 0);
 			goto retry;
 		}
 		IP_VS_DBG_RL("ip_route_output error, dest: %pI4\n", &daddr);
@@ -147,7 +147,7 @@ static struct rtable *do_output_route4(struct net *net, __be32 daddr,
 	} else if (!*saddr && rt_mode & IP_VS_RT_MODE_CONNECT && fl4.saddr) {
 		ip_rt_put(rt);
 		*saddr = fl4.saddr;
-		flowi4_update_output(&fl4, 0, 0, daddr, fl4.saddr);
+		flowi4_update_output(&fl4, 0, daddr, fl4.saddr);
 		loop = true;
 		goto retry;
 	}
diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c
index c365df24ad33..664d1f2e9121 100644
--- a/net/sctp/protocol.c
+++ b/net/sctp/protocol.c
@@ -500,9 +500,7 @@ static void sctp_v4_get_dst(struct sctp_transport *t, union sctp_addr *saddr,
 			continue;
 
 		fl4->fl4_sport = laddr->a.v4.sin_port;
-		flowi4_update_output(fl4,
-				     asoc->base.sk->sk_bound_dev_if,
-				     RT_CONN_FLAGS_TOS(asoc->base.sk, tos),
+		flowi4_update_output(fl4, asoc->base.sk->sk_bound_dev_if,
 				     daddr->v4.sin_addr.s_addr,
 				     laddr->a.v4.sin_addr.s_addr);
 
-- 
2.39.2

Re: [PATCH net-next] ipv4: Drop tos parameter from flowi4_update_output()

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (main)
by David S. Miller <davem@davemloft.net>:

On Thu, 1 Jun 2023 18:37:46 +0200 you wrote:
> Callers of flowi4_update_output() never try to update ->flowi4_tos:
> 
>   * ip_route_connect() updates ->flowi4_tos with its own current
>     value.
> 
>   * ip_route_newports() has two users: tcp_v4_connect() and
>     dccp_v4_connect. Both initialise fl4 with ip_route_connect(), which
>     in turn sets ->flowi4_tos with RT_TOS(inet_sk(sk)->tos) and
>     ->flowi4_scope based on SOCK_LOCALROUTE.
> 
> [...]

Here is the summary with links:
  - [net-next] ipv4: Drop tos parameter from flowi4_update_output()
    https://git.kernel.org/netdev/net-next/c/3f06760c00f5

You are awesome, thank you!
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