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Lock down parallel router_info list for tracking multicast IGMP

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versions of various routers seen:

- Introduce igmp_mtx.
- Protect global variable 'router_info_head' and list fields
  in struct router_info with this mutex, as well as
  igmp_timers_are_running.
- find_rti() asserts that the caller acquires igmp_mtx.
- Annotate a failure to check the return value of
  MALLOC(..., M_NOWAIT).
This commit is contained in:
Robert Watson 2004-06-11 03:42:37 +00:00
parent f64520dfb8
commit c14800e6ff
1 changed files with 27 additions and 1 deletions
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28
sys/netinet/igmp.c
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@ -80,10 +80,25 @@ static struct igmpstat igmpstat;
SYSCTL_STRUCT(_net_inet_igmp, IGMPCTL_STATS, stats, CTLFLAG_RW, &igmpstat,
igmpstat, "");
/*
* igmp_mtx protects all mutable global variables in igmp.c, as well as
* the data fields in struct router_info. In general, a router_info
* structure will be valid as long as the referencing struct in_multi is
* valid, so no reference counting is used. We allow unlocked reads of
* router_info data when accessed via an in_multi read-only.
*/
static struct mtx igmp_mtx;
static SLIST_HEAD(, router_info) router_info_head;
static int igmp_timers_are_running;
/*
* XXXRW: can we define these such that these can be made const? In any
* case, these shouldn't be changed after igmp_init() and therefore don't
* need locking.
*/
static u_long igmp_all_hosts_group;
static u_long igmp_all_rtrs_group;
static struct mbuf *router_alert;
static struct route igmprt;
@ -118,6 +133,7 @@ igmp_init(void)
ra->ipopt_list[3] = 0x00;
router_alert->m_len = sizeof(ra->ipopt_dst) + ra->ipopt_list[1];
mtx_init(&igmp_mtx, "igmp_mtx", NULL, MTX_DEF);
SLIST_INIT(&router_info_head);
}
@ -126,6 +142,7 @@ find_rti(struct ifnet *ifp)
{
struct router_info *rti;
mtx_assert(&igmp_mtx, MA_OWNED);
IGMP_PRINTF("[igmp.c, _find_rti] --> entering \n");
SLIST_FOREACH(rti, &router_info_head, rti_list) {
if (rti->rti_ifp == ifp) {
@ -134,6 +151,9 @@ find_rti(struct ifnet *ifp)
return rti;
}
}
/*
* XXXRW: return value of malloc not checked, despite M_NOWAIT.
*/
MALLOC(rti, struct router_info *, sizeof *rti, M_IGMP, M_NOWAIT);
rti->rti_ifp = ifp;
rti->rti_type = IGMP_V2_ROUTER;
@ -197,7 +217,6 @@ igmp_input(register struct mbuf *m, int off)
timer = igmp->igmp_code * PR_FASTHZ / IGMP_TIMER_SCALE;
if (timer == 0)
timer = 1;
rti = find_rti(ifp);
/*
* In the IGMPv2 specification, there are 3 states and a flag.
@ -224,8 +243,11 @@ igmp_input(register struct mbuf *m, int off)
* value in RFC 1112.
*/
mtx_lock(&igmp_mtx);
rti = find_rti(ifp);
rti->rti_type = IGMP_V1_ROUTER;
rti->rti_time = 0;
mtx_unlock(&igmp_mtx);
timer = IGMP_MAX_HOST_REPORT_DELAY * PR_FASTHZ;
@ -344,7 +366,9 @@ igmp_joingroup(struct in_multi *inm)
inm->inm_timer = 0;
inm->inm_state = IGMP_OTHERMEMBER;
} else {
mtx_lock(&igmp_mtx);
inm->inm_rti = find_rti(inm->inm_ifp);
mtx_unlock(&igmp_mtx);
igmp_sendpkt(inm, inm->inm_rti->rti_type, 0);
inm->inm_timer = IGMP_RANDOM_DELAY(
IGMP_MAX_HOST_REPORT_DELAY*PR_FASTHZ);
@ -404,6 +428,7 @@ igmp_slowtimo(void)
struct router_info *rti;
IGMP_PRINTF("[igmp.c,_slowtimo] -- > entering \n");
mtx_lock(&igmp_mtx);
SLIST_FOREACH(rti, &router_info_head, rti_list) {
if (rti->rti_type == IGMP_V1_ROUTER) {
rti->rti_time++;
@ -411,6 +436,7 @@ igmp_slowtimo(void)
rti->rti_type = IGMP_V2_ROUTER;
}
}
mtx_unlock(&igmp_mtx);
IGMP_PRINTF("[igmp.c,_slowtimo] -- > exiting \n");
splx(s);
}