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ipv6: optimize fl6_update_dst()

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fl6_update_dst() is called for every TCP (and others) transmit,
and is a nop for common cases.

Split it in two parts :

1) fl6_update_dst() inline helper, small and fast.

2) __fl6_update_dst() for the exception, out of line.

Small size increase to get better TX performance.

$ scripts/bloat-o-meter -t vmlinux.old vmlinux.new
add/remove: 2/2 grow/shrink: 8/0 up/down: 296/-125 (171)
Function                                     old     new   delta
__fl6_update_dst                               -     104    +104
rawv6_sendmsg                               2244    2284     +40
udpv6_sendmsg                               3013    3043     +30
tcp_v6_connect                              1514    1534     +20
cookie_v6_check                             1501    1519     +18
ip6_datagram_dst_update                      673     690     +17
inet6_sk_rebuild_header                      499     516     +17
inet6_csk_route_socket                       507     524     +17
inet6_csk_route_req                          343     360     +17
__pfx___fl6_update_dst                         -      16     +16
__pfx_fl6_update_dst                          16       -     -16
fl6_update_dst                               109       -    -109
Total: Before=22570304, After=22570475, chg +0.00%

Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260128185548.3738781-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet 2026-01-28 18:55:47 +00:00 committed by Jakub Kicinski
parent 70e9a5760a
commit b1cd687e3e
2 changed files with 20 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
include/net/ipv6.h
View File

@ -1174,9 +1174,19 @@ int ipv6_find_hdr(const struct sk_buff *skb, unsigned int *offset, int target,
int ipv6_find_tlv(const struct sk_buff *skb, int offset, int type);
struct in6_addr *fl6_update_dst(struct flowi6 *fl6,
const struct ipv6_txoptions *opt,
struct in6_addr *orig);
struct in6_addr *__fl6_update_dst(struct flowi6 *fl6,
const struct ipv6_txoptions *opt,
struct in6_addr *orig);
static inline struct in6_addr *
fl6_update_dst(struct flowi6 *fl6, const struct ipv6_txoptions *opt,
struct in6_addr *orig)
{
if (likely(!opt))
return NULL;
return __fl6_update_dst(fl6, opt, orig);
}
/*
* socket options (ipv6_sockglue.c)

14
net/ipv6/exthdrs.c
View File

@ -1336,21 +1336,21 @@ struct ipv6_txoptions *__ipv6_fixup_options(struct ipv6_txoptions *opt_space,
EXPORT_SYMBOL_GPL(__ipv6_fixup_options);
/**
* fl6_update_dst - update flowi destination address with info given
* __fl6_update_dst - update flowi destination address with info given
* by srcrt option, if any.
*
* @fl6: flowi6 for which daddr is to be updated
* @opt: struct ipv6_txoptions in which to look for srcrt opt
* @orig: copy of original daddr address if modified
*
* Returns NULL if no txoptions or no srcrt, otherwise returns orig
* Return: NULL if no srcrt or invalid srcrt type, otherwise returns orig
* and initial value of fl6->daddr set in orig
*/
struct in6_addr *fl6_update_dst(struct flowi6 *fl6,
const struct ipv6_txoptions *opt,
struct in6_addr *orig)
struct in6_addr *__fl6_update_dst(struct flowi6 *fl6,
const struct ipv6_txoptions *opt,
struct in6_addr *orig)
{
if (!opt || !opt->srcrt)
if (!opt->srcrt)
return NULL;
*orig = fl6->daddr;
@ -1374,4 +1374,4 @@ struct in6_addr *fl6_update_dst(struct flowi6 *fl6,
return orig;
}
EXPORT_SYMBOL_GPL(fl6_update_dst);
EXPORT_SYMBOL_GPL(__fl6_update_dst);