Commit e57a3447 authored by Yan Zhai's avatar Yan Zhai Committed by Jakub Kicinski
Browse files

ipv6: drop feature RTAX_FEATURE_ALLFRAG 

RTAX_FEATURE_ALLFRAG was added before the first git commit:

https://www.mail-archive.com/bk-commits-head@vger.kernel.org/msg03399.html



The feature would send packets to the fragmentation path if a box
receives a PMTU value with less than 1280 byte. However, since commit
9d289715 ("ipv6: stop sending PTB packets for MTU < 1280"), such
message would be simply discarded. The feature flag is neither supported
in iproute2 utility. In theory one can still manipulate it with direct
netlink message, but it is not ideal because it was based on obsoleted
guidance of RFC-2460 (replaced by RFC-8200).

The feature would always test false at the moment, so remove related
code or mark them as unused.

Signed-off-by: default avatarYan Zhai <yan@cloudflare.com>
Reviewed-by: default avatarFlorian Westphal <fw@strlen.de>
Reviewed-by: default avatarEric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/d78e44dcd9968a252143ffe78460446476a472a1.1698156966.git.yan@cloudflare.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 8846f9a0

include/net/dst.h

+0 −7
Original line number Diff line number Diff line
@@ -222,13 +222,6 @@ static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metr 
	return msecs_to_jiffies(dst_metric(dst, metric));

}



static inline u32

dst_allfrag(const struct dst_entry *dst)

{

	int ret = dst_feature(dst,  RTAX_FEATURE_ALLFRAG);

	return ret;

}



static inline int

dst_metric_locked(const struct dst_entry *dst, int metric)

{

include/net/inet_connection_sock.h

+0 −1
Original line number Diff line number Diff line
@@ -44,7 +44,6 @@ struct inet_connection_sock_af_ops { 
				      struct request_sock *req_unhash,

				      bool *own_req);

	u16	    net_header_len;

	u16	    net_frag_header_len;

	u16	    sockaddr_len;

	int	    (*setsockopt)(struct sock *sk, int level, int optname,

				  sockptr_t optval, unsigned int optlen);

include/net/inet_sock.h

+0 −1
Original line number Diff line number Diff line
@@ -244,7 +244,6 @@ struct inet_sock { 
};



#define IPCORK_OPT	1	/* ip-options has been held in ipcork.opt */

#define IPCORK_ALLFRAG	2	/* always fragment (for ipv6 for now) */



enum {

	INET_FLAGS_PKTINFO	= 0,

include/uapi/linux/rtnetlink.h

+1 −1
Original line number Diff line number Diff line
@@ -505,7 +505,7 @@ enum { 
#define RTAX_FEATURE_ECN		(1 << 0)

#define RTAX_FEATURE_SACK		(1 << 1) /* unused */

#define RTAX_FEATURE_TIMESTAMP		(1 << 2) /* unused */

#define RTAX_FEATURE_ALLFRAG		(1 << 3)

#define RTAX_FEATURE_ALLFRAG		(1 << 3) /* unused */

#define RTAX_FEATURE_TCP_USEC_TS	(1 << 4)



#define RTAX_FEATURE_MASK	(RTAX_FEATURE_ECN |		\

net/ipv4/tcp_output.c

+1 −19
Original line number Diff line number Diff line
@@ -1698,14 +1698,6 @@ static inline int __tcp_mtu_to_mss(struct sock *sk, int pmtu) 
	 */

	mss_now = pmtu - icsk->icsk_af_ops->net_header_len - sizeof(struct tcphdr);



	/* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */

	if (icsk->icsk_af_ops->net_frag_header_len) {

		const struct dst_entry *dst = __sk_dst_get(sk);



		if (dst && dst_allfrag(dst))

			mss_now -= icsk->icsk_af_ops->net_frag_header_len;

	}



	/* Clamp it (mss_clamp does not include tcp options) */

	if (mss_now > tp->rx_opt.mss_clamp)

		mss_now = tp->rx_opt.mss_clamp;
@@ -1733,21 +1725,11 @@ int tcp_mss_to_mtu(struct sock *sk, int mss) 
{

	const struct tcp_sock *tp = tcp_sk(sk);

	const struct inet_connection_sock *icsk = inet_csk(sk);

	int mtu;



	mtu = mss +

	return mss +

	      tp->tcp_header_len +

	      icsk->icsk_ext_hdr_len +

	      icsk->icsk_af_ops->net_header_len;



	/* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */

	if (icsk->icsk_af_ops->net_frag_header_len) {

		const struct dst_entry *dst = __sk_dst_get(sk);



		if (dst && dst_allfrag(dst))

			mtu += icsk->icsk_af_ops->net_frag_header_len;

	}

	return mtu;

}

EXPORT_SYMBOL(tcp_mss_to_mtu);