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Code Issues Releases Activity

Finish r274175: do control plane MTU tracking.

Browse Source 
Update route MTU in case of ifnet MTU change.
Add new RTF_FIXEDMTU to track explicitly specified MTU.

Old behavior:
ifconfig em0 mtu 1500->9000 -> all routes traversing em0 do not change MTU.
User has to manually update all routes.
ifconfig em0 mtu 9000->1500 -> all routes traversing em0 do not change MTU.
However, if ip[6]_output finds route with rt_mtu > interface mtu, rt_mtu
gets updated.

New behavior:
ifconfig em0 mtu 1500->9000 -> all interface routes in all fibs gets updated
with new MTU unless RTF_FIXEDMTU flag set on them.
ifconfig em0 mtu 9000->1500 -> all routes in all fibs gets updated with new
MTU unless RTF_FIXEDMTU flag set on them AND rt_mtu is less than ifp mtu.

route add ... -mtu XXX automatically sets RTF_FIXEDMTU flag.
route change .. -mtu 0 automatically removes RTF_FIXEDMTU flag.

PR:		194238
MFC after:	1 month
CR:		D1125
This commit is contained in:
Alexander V. Chernikov 2014-11-17 01:05:29 +00:00
parent e93397e537
commit 7f948f12f6
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=274611
6 changed files with 105 additions and 28 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
sbin/route/route.c
View File

@ -1587,7 +1587,7 @@ static const char routeflags[] =
"\1UP\2GATEWAY\3HOST\4REJECT\5DYNAMIC\6MODIFIED\7DONE"
"\012XRESOLVE\013LLINFO\014STATIC\015BLACKHOLE"
"\017PROTO2\020PROTO1\021PRCLONING\022WASCLONED\023PROTO3"
"\025PINNED\026LOCAL\027BROADCAST\030MULTICAST\035STICKY";
"\024FIXEDMTU\025PINNED\026LOCAL\027BROADCAST\030MULTICAST\035STICKY";
static const char ifnetflags[] =
"\1UP\2BROADCAST\3DEBUG\4LOOPBACK\5PTP\6b6\7RUNNING\010NOARP"
"\011PPROMISC\012ALLMULTI\013OACTIVE\014SIMPLEX\015LINK0\016LINK1"

1
sys/net/if.c
View File

@ -2494,6 +2494,7 @@ ifhwioctl(u_long cmd, struct ifnet *ifp, caddr_t data, struct thread *td)
#ifdef INET6
nd6_setmtu(ifp);
#endif
rt_updatemtu(ifp);
}
break;
}

102
sys/net/route.c
View File

@ -141,6 +141,14 @@ static int rtrequest1_fib_change(struct radix_node_head *, struct rt_addrinfo *,
struct rtentry **, u_int);
static void rt_setmetrics(const struct rt_addrinfo *, struct rtentry *);
struct if_mtuinfo
{
struct ifnet *ifp;
int mtu;
};
static int if_updatemtu_cb(struct radix_node *, void *);
/*
* handler for net.my_fibnum
*/
@ -947,6 +955,70 @@ rt_expunge(struct radix_node_head *rnh, struct rtentry *rt)
return (error);
}
static int
if_updatemtu_cb(struct radix_node *rn, void *arg)
{
struct rtentry *rt;
struct if_mtuinfo *ifmtu;
rt = (struct rtentry *)rn;
ifmtu = (struct if_mtuinfo *)arg;
if (rt->rt_ifp != ifmtu->ifp)
return (0);
if (rt->rt_mtu >= ifmtu->mtu) {
/* We have to decrease mtu regardless of flags */
rt->rt_mtu = ifmtu->mtu;
return (0);
}
/*
* New MTU is bigger. Check if are allowed to alter it
*/
if ((rt->rt_flags & (RTF_FIXEDMTU | RTF_GATEWAY | RTF_HOST)) != 0) {
/*
* Skip routes with user-supplied MTU and
* non-interface routes
*/
return (0);
}
/* We are safe to update route MTU */
rt->rt_mtu = ifmtu->mtu;
return (0);
}
void
rt_updatemtu(struct ifnet *ifp)
{
struct if_mtuinfo ifmtu;
struct radix_node_head *rnh;
int i, j;
ifmtu.ifp = ifp;
/*
* Try to update rt_mtu for all routes using this interface
* Unfortunately the only way to do this is to traverse all
* routing tables in all fibs/domains.
*/
for (i = 1; i <= AF_MAX; i++) {
ifmtu.mtu = if_getmtu_family(ifp, i);
for (j = 0; j < rt_numfibs; j++) {
rnh = rt_tables_get_rnh(j, i);
if (rnh == NULL)
continue;
RADIX_NODE_HEAD_LOCK(rnh);
rnh->rnh_walktree(rnh, if_updatemtu_cb, &ifmtu);
RADIX_NODE_HEAD_UNLOCK(rnh);
}
}
}
#if 0
int p_sockaddr(char *buf, int buflen, struct sockaddr *s);
int rt_print(char *buf, int buflen, struct rtentry *rt);
@ -1408,6 +1480,7 @@ rtrequest1_fib_change(struct radix_node_head *rnh, struct rt_addrinfo *info,
int error = 0;
int free_ifa = 0;
int family, mtu;
struct if_mtuinfo ifmtu;
rt = (struct rtentry *)rnh->rnh_lookup(info->rti_info[RTAX_DST],
info->rti_info[RTAX_NETMASK], rnh);
@ -1478,12 +1551,19 @@ rtrequest1_fib_change(struct radix_node_head *rnh, struct rt_addrinfo *info,
if (rt->rt_ifa && rt->rt_ifa->ifa_rtrequest != NULL)
rt->rt_ifa->ifa_rtrequest(RTM_ADD, rt, info);
/* Ensure route MTU is not bigger than interface MTU */
/* Alter route MTU if necessary */
if (rt->rt_ifp != NULL) {
family = info->rti_info[RTAX_DST]->sa_family;
mtu = if_getmtu_family(rt->rt_ifp, family);
if (rt->rt_mtu > mtu)
/* Set default MTU */
if (rt->rt_mtu == 0)
rt->rt_mtu = mtu;
if (rt->rt_mtu != mtu) {
/* Check if we really need to update */
ifmtu.ifp = rt->rt_ifp;
ifmtu.mtu = mtu;
if_updatemtu_cb(rt->rt_nodes, &ifmtu);
}
}
if (ret_nrt) {
@ -1501,8 +1581,24 @@ static void
rt_setmetrics(const struct rt_addrinfo *info, struct rtentry *rt)
{
if (info->rti_mflags & RTV_MTU)
if (info->rti_mflags & RTV_MTU) {
if (info->rti_rmx->rmx_mtu != 0) {
/*
* MTU was explicitly provided by user.
* Keep it.
*/
rt->rt_flags |= RTF_FIXEDMTU;
} else {
/*
* User explicitly sets MTU to 0.
* Assume rollback to default.
*/
rt->rt_flags &= ~RTF_FIXEDMTU;
}
rt->rt_mtu = info->rti_rmx->rmx_mtu;
}
if (info->rti_mflags & RTV_WEIGHT)
rt->rt_weight = info->rti_rmx->rmx_weight;
/* Kernel -> userland timebase conversion. */

3
sys/net/route.h
View File

@ -151,7 +151,7 @@ struct rtentry {
/* 0x10000 unused, was RTF_PRCLONING */
/* 0x20000 unused, was RTF_WASCLONED */
#define RTF_PROTO3 0x40000 /* protocol specific routing flag */
/* 0x80000 unused */
#define RTF_FIXEDMTU 0x80000 /* MTU was explicitly specified */
#define RTF_PINNED 0x100000 /* route is immutable */
#define RTF_LOCAL 0x200000 /* route represents a local address */
#define RTF_BROADCAST 0x400000 /* route represents a bcast address */
@ -378,6 +378,7 @@ int rtsock_routemsg(int, struct ifnet *ifp, int, struct rtentry *, int);
int rt_expunge(struct radix_node_head *, struct rtentry *);
void rtfree(struct rtentry *);
int rt_check(struct rtentry **, struct rtentry **, struct sockaddr *);
void rt_updatemtu(struct ifnet *);
/* XXX MRT COMPAT VERSIONS THAT SET UNIVERSE to 0 */
/* Thes are used by old code not yet converted to use multiple FIBS */

14
sys/netinet/ip_output.c
View File

@ -322,20 +322,10 @@ ip_output(struct mbuf *m, struct mbuf *opt, struct route *ro, int flags,
* Calculate MTU. If we have a route that is up, use that,
* otherwise use the interface's MTU.
*/
if (rte != NULL && (rte->rt_flags & (RTF_UP|RTF_HOST))) {
/*
* This case can happen if the user changed the MTU
* of an interface after enabling IP on it. Because
* most netifs don't keep track of routes pointing to
* them, there is no way for one to update all its
* routes when the MTU is changed.
*/
if (rte->rt_mtu > ifp->if_mtu)
rte->rt_mtu = ifp->if_mtu;
if (rte != NULL && (rte->rt_flags & (RTF_UP|RTF_HOST)))
mtu = rte->rt_mtu;
} else {
else
mtu = ifp->if_mtu;
}
/* Catch a possible divide by zero later. */
KASSERT(mtu > 0, ("%s: mtu %d <= 0, rte=%p (rt_flags=0x%08x) ifp=%p",
__func__, mtu, rte, (rte != NULL) ? rte->rt_flags : 0, ifp));

11
sys/netinet6/ip6_output.c
View File

@ -1275,17 +1275,6 @@ ip6_getpmtu(struct route_in6 *ro_pmtu, struct route_in6 *ro,
*/
alwaysfrag = 1;
mtu = IPV6_MMTU;
} else if (mtu > ifmtu) {
/*
* The MTU on the route is larger than the MTU on
* the interface! This shouldn't happen, unless the
* MTU of the interface has been changed after the
* interface was brought up. Change the MTU in the
* route to match the interface MTU (as long as the
* field isn't locked).
*/
mtu = ifmtu;
ro_pmtu->ro_rt->rt_mtu = mtu;
}
} else if (ifp) {
mtu = IN6_LINKMTU(ifp);