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Resurrect RTF_RNH_LOCKED flag and restore ability to call rtalloc1_fib()

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with acquired RIB lock.

This fixes a possible panic due to trying to acquire RIB rlock when it is
already exclusive locked.

PR:		215963, 215122
MFC after:	1 week
Sponsored by:	Yandex LLC
This commit is contained in:
Andrey V. Elsukov 2017-06-13 10:52:31 +00:00
parent dfde8e4b54
commit b83aa367a5
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=319895
2 changed files with 19 additions and 7 deletions
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24
sys/net/route.c
View File

@ -454,18 +454,23 @@ rtalloc1_fib(struct sockaddr *dst, int report, u_long ignflags,
/*
* Look up the address in the table for that Address Family
*/
RIB_RLOCK(rh);
if ((ignflags & RTF_RNH_LOCKED) == 0)
RIB_RLOCK(rh);
#ifdef INVARIANTS
else
RIB_LOCK_ASSERT(rh);
#endif
rn = rh->rnh_matchaddr(dst, &rh->head);
if (rn && ((rn->rn_flags & RNF_ROOT) == 0)) {
newrt = RNTORT(rn);
RT_LOCK(newrt);
RT_ADDREF(newrt);
RIB_RUNLOCK(rh);
if ((ignflags & RTF_RNH_LOCKED) == 0)
RIB_RUNLOCK(rh);
return (newrt);
} else
} else if ((ignflags & RTF_RNH_LOCKED) == 0)
RIB_RUNLOCK(rh);
/*
* Either we hit the root or could not find any match,
* which basically means: "cannot get there from here".
@ -748,7 +753,9 @@ ifa_ifwithroute(int flags, const struct sockaddr *dst, struct sockaddr *gateway,
if (ifa == NULL)
ifa = ifa_ifwithnet(gateway, 0, fibnum);
if (ifa == NULL) {
struct rtentry *rt = rtalloc1_fib(gateway, 0, 0, fibnum);
struct rtentry *rt;
rt = rtalloc1_fib(gateway, 0, flags, fibnum);
if (rt == NULL)
return (NULL);
/*
@ -1838,8 +1845,13 @@ rtrequest1_fib_change(struct rib_head *rnh, struct rt_addrinfo *info,
info->rti_info[RTAX_IFP] != NULL ||
(info->rti_info[RTAX_IFA] != NULL &&
!sa_equal(info->rti_info[RTAX_IFA], rt->rt_ifa->ifa_addr))) {
/*
* XXX: Temporarily set RTF_RNH_LOCKED flag in the rti_flags
* to avoid rlock in the ifa_ifwithroute().
*/
info->rti_flags |= RTF_RNH_LOCKED;
error = rt_getifa_fib(info, fibnum);
info->rti_flags &= ~RTF_RNH_LOCKED;
if (info->rti_ifa != NULL)
free_ifa = 1;

2
sys/net/route.h
View File

@ -189,7 +189,7 @@ struct rtentry {
/* 0x8000000 and up unassigned */
#define RTF_STICKY 0x10000000 /* always route dst->src */
#define RTF_RNH_LOCKED 0x40000000 /* unused */
#define RTF_RNH_LOCKED 0x40000000 /* radix node head is locked */
#define RTF_GWFLAG_COMPAT 0x80000000 /* a compatibility bit for interacting
with existing routing apps */