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unlock igmp and mld6 fast timer
On Fri, Jan 02, 2026 at 01:58:09PM +0100, Alexander Bluhm wrote:
> On Fri, Jan 02, 2026 at 06:32:31AM +0000, Vitaliy Makkoveev wrote:
> > On Mon, Dec 29, 2025 at 01:20:05PM +0100, Alexander Bluhm wrote:
> > > On Tue, Dec 02, 2025 at 11:01:36PM +0100, Alexander Bluhm wrote:
> > > > Hi,
> > > >
> > > > After moving around code for a while, I think a rwlock to protect
> > > > if_maddrlist is the next step. The malloc(M_WAITOK) in rti_fill()
> > > > prevents us from using a mutex here.
> > > >
> > > > So protect the TAILQ if_maddrlist with rwlock if_maddrlock. Also
> > > > struct in_multi and in6_multi use this lock for their state and
> > > > timer. Sleeps in malloc and IP output are possible.
> > > >
> > > > This allows to run IGMP and MLD6 fast timeout with shared net lock.
> > >
> > > I would like to proceed with MP multicast.
> > >
> > > OK? objections?
> > >
> >
> > Just for curiosity, why have you replaced mutex with rwlock?
>
> There is this call path, I found the sleeping point during testing.
>
> in_addmulti()
> rw_enter_write(&ifp->if_maddrlock)
> igmp_joingroup()
> rti_fill()
> malloc(M_WAITOK)
>
> Maybe I can pull the M_WAITOK out of the lock later. Sleeping for
> memory with a rwlock held is not optimal. But moving the malloc
> and replacing the lock with a mutex requires more refacotring. Not
> sure if it is worth it.
>
> IPv6 is different, it uses M_NOWAIT. But that means a system call
> can fail due to low memory situations. Also not good, sleeping
> would be better.
>
> > in{,6}_var.h have missing locks description. Can you add something
> > like of 'if_maddrlock rwlock of parent interface' for [m]? And
> > description for [I] too.
>
> done
>
> > The rest looks good to me.
The diff was not quite right. syzkaller found that in_addmulti ->
igmp_joingroup -> igmp_sendpkt -> ip_output -> in_hasmulti is a bad
idea. The lock was taken twice. I have backed it out.
https://syzkaller.appspot.com/bug?extid=de6bcf8e746b8a631885
Fortunately I was working on a follow up diff. Idea is that
igmp_sendpkt() is called after the lock has been released. Struct
igmp_pktinfo contains everything that is needed to send an IGMP
packet later. In case of timeout loops a bunch of such packets are
queued.
Diff below contains the previous locking diff with igmp_sendpkt()
on top. MLD6 is analog to IGMP. If it helps review, I can also
split it up.
ok?
bluhm
Index: net/if.c
===================================================================
RCS file: /data/mirror/openbsd/cvs/src/sys/net/if.c,v
diff -u -p -r1.762 if.c
--- net/if.c 3 Jan 2026 14:10:04 -0000 1.762
+++ net/if.c 3 Jan 2026 14:22:23 -0000
@@ -662,6 +662,7 @@ if_attach_common(struct ifnet *ifp)
TAILQ_INIT(&ifp->if_addrlist);
TAILQ_INIT(&ifp->if_maddrlist);
TAILQ_INIT(&ifp->if_groups);
+ rw_init(&ifp->if_maddrlock, "maddr");
if (!ISSET(ifp->if_xflags, IFXF_MPSAFE)) {
KASSERTMSG(ifp->if_qstart == NULL,
Index: net/if_var.h
===================================================================
RCS file: /data/mirror/openbsd/cvs/src/sys/net/if_var.h,v
diff -u -p -r1.147 if_var.h
--- net/if_var.h 3 Jan 2026 14:10:04 -0000 1.147
+++ net/if_var.h 3 Jan 2026 14:22:23 -0000
@@ -81,6 +81,7 @@
* K kernel lock
* N net lock
* T if_tmplist_lock
+ * m interface multicast rwlock if_maddrlock
*
* For SRP related structures that allow lock-free reads, the write lock
* is indicated below.
@@ -153,8 +154,9 @@ struct ifnet { /* and the entries */
TAILQ_ENTRY(ifnet) if_list; /* [NK] all struct ifnets are chained */
TAILQ_ENTRY(ifnet) if_tmplist; /* [T] temporary list */
TAILQ_HEAD(, ifaddr) if_addrlist; /* [N] list of addresses per if */
- TAILQ_HEAD(, ifmaddr) if_maddrlist; /* [N] list of multicast records */
+ TAILQ_HEAD(, ifmaddr) if_maddrlist; /* [m] list of multicast records */
TAILQ_HEAD(, ifg_list) if_groups; /* [N] list of groups per if */
+ struct rwlock if_maddrlock;
struct task_list if_addrhooks; /* [I] address change callbacks */
struct task_list if_linkstatehooks; /* [I] link change callbacks*/
struct task_list if_detachhooks; /* [I] detach callbacks */
@@ -273,10 +275,10 @@ struct ifaddr {
* Interface multicast address.
*/
struct ifmaddr {
- struct sockaddr *ifma_addr; /* Protocol address */
- unsigned int ifma_ifidx; /* Index of the interface */
+ TAILQ_ENTRY(ifmaddr) ifma_list; /* [m] Per-interface list */
+ struct sockaddr *ifma_addr; /* [I] Protocol address */
struct refcnt ifma_refcnt; /* Count of references */
- TAILQ_ENTRY(ifmaddr) ifma_list; /* Per-interface list */
+ unsigned int ifma_ifidx; /* [I] Index of the interface */
};
/*
Index: netinet/igmp.c
===================================================================
RCS file: /data/mirror/openbsd/cvs/src/sys/netinet/igmp.c,v
diff -u -p -r1.95 igmp.c
--- netinet/igmp.c 3 Jan 2026 14:10:04 -0000 1.95
+++ netinet/igmp.c 3 Jan 2026 14:31:34 -0000
@@ -118,8 +118,7 @@ static LIST_HEAD(, router_info) rti_head
static struct mbuf *router_alert;
struct cpumem *igmpcounters;
-int igmp_checktimer(struct ifnet *);
-void igmp_sendpkt(struct ifnet *, struct in_multi *, int, in_addr_t);
+int igmp_checktimer(struct ifnet *, struct igmp_pktlist *);
int rti_fill(struct in_multi *);
int rti_reset(struct ifnet *);
int igmp_input_if(struct ifnet *, struct mbuf **, int *, int, int,
@@ -341,6 +340,7 @@ igmp_input_if(struct ifnet *ifp, struct
* except those that are already running and those
* that belong to a "local" group (224.0.0.X).
*/
+ rw_enter_write(&ifp->if_maddrlock);
TAILQ_FOREACH(ifma, &ifp->if_maddrlist, ifma_list) {
if (ifma->ifma_addr->sa_family != AF_INET)
continue;
@@ -353,6 +353,7 @@ igmp_input_if(struct ifnet *ifp, struct
running = 1;
}
}
+ rw_exit_write(&ifp->if_maddrlock);
} else {
if (!IN_MULTICAST(ip->ip_dst.s_addr)) {
igmpstat_inc(igps_rcv_badqueries);
@@ -372,6 +373,7 @@ igmp_input_if(struct ifnet *ifp, struct
* timers already running, check if they need to be
* reset.
*/
+ rw_enter_write(&ifp->if_maddrlock);
TAILQ_FOREACH(ifma, &ifp->if_maddrlist, ifma_list) {
if (ifma->ifma_addr->sa_family != AF_INET)
continue;
@@ -400,6 +402,7 @@ igmp_input_if(struct ifnet *ifp, struct
}
}
}
+ rw_exit_write(&ifp->if_maddrlock);
}
break;
@@ -436,6 +439,7 @@ igmp_input_if(struct ifnet *ifp, struct
* If we belong to the group being reported, stop
* our timer for that group.
*/
+ rw_enter_write(&ifp->if_maddrlock);
inm = in_lookupmulti(&igmp->igmp_group, ifp);
if (inm != NULL) {
inm->inm_timer = 0;
@@ -456,6 +460,7 @@ igmp_input_if(struct ifnet *ifp, struct
break;
}
}
+ rw_exit_write(&ifp->if_maddrlock);
break;
@@ -504,6 +509,7 @@ igmp_input_if(struct ifnet *ifp, struct
* If we belong to the group being reported, stop
* our timer for that group.
*/
+ rw_enter_write(&ifp->if_maddrlock);
inm = in_lookupmulti(&igmp->igmp_group, ifp);
if (inm != NULL) {
inm->inm_timer = 0;
@@ -520,6 +526,7 @@ igmp_input_if(struct ifnet *ifp, struct
break;
}
}
+ rw_exit_write(&ifp->if_maddrlock);
break;
@@ -538,16 +545,22 @@ igmp_input_if(struct ifnet *ifp, struct
}
void
-igmp_joingroup(struct in_multi *inm, struct ifnet *ifp)
+igmp_joingroup(struct in_multi *inm, struct ifnet *ifp,
+ struct igmp_pktinfo *pkt)
{
- int i, running = 0;
+ int running = 0;
+
+ rw_assert_wrlock(&ifp->if_maddrlock);
inm->inm_state = IGMP_IDLE_MEMBER;
if (!IN_LOCAL_GROUP(inm->inm_addr.s_addr) &&
(ifp->if_flags & IFF_LOOPBACK) == 0) {
- i = rti_fill(inm);
- igmp_sendpkt(ifp, inm, i, 0);
+ pkt->ipi_addr = inm->inm_addr;
+ pkt->ipi_rdomain = ifp->if_rdomain;
+ pkt->ipi_ifidx = inm->inm_ifidx;
+ pkt->ipi_type = rti_fill(inm);
+
inm->inm_state = IGMP_DELAYING_MEMBER;
inm->inm_timer = IGMP_RANDOM_DELAY(
IGMP_MAX_HOST_REPORT_DELAY * PR_FASTHZ);
@@ -562,17 +575,22 @@ igmp_joingroup(struct in_multi *inm, str
}
void
-igmp_leavegroup(struct in_multi *inm, struct ifnet *ifp)
+igmp_leavegroup(struct in_multi *inm, struct ifnet *ifp,
+ struct igmp_pktinfo *pkt)
{
+ rw_assert_anylock(&ifp->if_maddrlock);
+
switch (inm->inm_state) {
case IGMP_DELAYING_MEMBER:
case IGMP_IDLE_MEMBER:
if (!IN_LOCAL_GROUP(inm->inm_addr.s_addr) &&
(ifp->if_flags & IFF_LOOPBACK) == 0)
- if (inm->inm_rti->rti_type != IGMP_v1_ROUTER)
- igmp_sendpkt(ifp, inm,
- IGMP_HOST_LEAVE_MESSAGE,
- INADDR_ALLROUTERS_GROUP);
+ if (inm->inm_rti->rti_type != IGMP_v1_ROUTER) {
+ pkt->ipi_addr.s_addr = INADDR_ALLROUTERS_GROUP;
+ pkt->ipi_rdomain = ifp->if_rdomain;
+ pkt->ipi_ifidx = inm->inm_ifidx;
+ pkt->ipi_type = IGMP_HOST_LEAVE_MESSAGE;
+ }
break;
case IGMP_LAZY_MEMBER:
case IGMP_AWAKENING_MEMBER:
@@ -584,6 +602,7 @@ igmp_leavegroup(struct in_multi *inm, st
void
igmp_fasttimo(void)
{
+ struct igmp_pktlist pktlist;
struct ifnet *ifp;
int running = 0;
@@ -598,28 +617,37 @@ igmp_fasttimo(void)
return;
membar_consumer();
- NET_LOCK();
+ NET_LOCK_SHARED();
+ STAILQ_INIT(&pktlist);
TAILQ_FOREACH(ifp, &ifnetlist, if_list) {
- if (igmp_checktimer(ifp))
+ if (igmp_checktimer(ifp, &pktlist))
running = 1;
}
membar_producer();
atomic_store_int(&igmp_timers_are_running, running);
- NET_UNLOCK();
+ while (!STAILQ_EMPTY(&pktlist)) {
+ struct igmp_pktinfo *pkt;
+
+ pkt = STAILQ_FIRST(&pktlist);
+ STAILQ_REMOVE_HEAD(&pktlist, ipi_list);
+ igmp_sendpkt(pkt);
+ free(pkt, M_MRTABLE, sizeof(*pkt));
+ }
+
+ NET_UNLOCK_SHARED();
}
int
-igmp_checktimer(struct ifnet *ifp)
+igmp_checktimer(struct ifnet *ifp, struct igmp_pktlist *pktlist)
{
struct in_multi *inm;
struct ifmaddr *ifma;
int running = 0;
- NET_ASSERT_LOCKED();
-
+ rw_enter_write(&ifp->if_maddrlock);
TAILQ_FOREACH(ifma, &ifp->if_maddrlist, ifma_list) {
if (ifma->ifma_addr->sa_family != AF_INET)
continue;
@@ -628,18 +656,26 @@ igmp_checktimer(struct ifnet *ifp)
/* do nothing */
} else if (--inm->inm_timer == 0) {
if (inm->inm_state == IGMP_DELAYING_MEMBER) {
- if (inm->inm_rti->rti_type == IGMP_v1_ROUTER)
- igmp_sendpkt(ifp, inm,
- IGMP_v1_HOST_MEMBERSHIP_REPORT, 0);
- else
- igmp_sendpkt(ifp, inm,
- IGMP_v2_HOST_MEMBERSHIP_REPORT, 0);
+ struct igmp_pktinfo *pkt;
+
inm->inm_state = IGMP_IDLE_MEMBER;
+ pkt = malloc(sizeof(*pkt), M_MRTABLE, M_NOWAIT);
+ if (pkt == NULL)
+ continue;
+ pkt->ipi_addr = inm->inm_addr;
+ pkt->ipi_rdomain = ifp->if_rdomain;
+ pkt->ipi_ifidx = inm->inm_ifidx;
+ pkt->ipi_type =
+ inm->inm_rti->rti_type == IGMP_v1_ROUTER ?
+ IGMP_v1_HOST_MEMBERSHIP_REPORT :
+ IGMP_v2_HOST_MEMBERSHIP_REPORT;
+ STAILQ_INSERT_TAIL(pktlist, pkt, ipi_list);
}
} else {
running = 1;
}
}
+ rw_exit_write(&ifp->if_maddrlock);
return (running);
}
@@ -660,8 +696,7 @@ igmp_slowtimo(void)
}
void
-igmp_sendpkt(struct ifnet *ifp, struct in_multi *inm, int type,
- in_addr_t addr)
+igmp_sendpkt(struct igmp_pktinfo *pkt)
{
struct mbuf *m;
struct igmp *igmp;
@@ -686,25 +721,21 @@ igmp_sendpkt(struct ifnet *ifp, struct i
ip->ip_off = 0;
ip->ip_p = IPPROTO_IGMP;
ip->ip_src.s_addr = INADDR_ANY;
- if (addr) {
- ip->ip_dst.s_addr = addr;
- } else {
- ip->ip_dst = inm->inm_addr;
- }
+ ip->ip_dst = pkt->ipi_addr;
m->m_data += sizeof(struct ip);
m->m_len -= sizeof(struct ip);
igmp = mtod(m, struct igmp *);
- igmp->igmp_type = type;
+ igmp->igmp_type = pkt->ipi_type;
igmp->igmp_code = 0;
- igmp->igmp_group = inm->inm_addr;
+ igmp->igmp_group = pkt->ipi_addr;
igmp->igmp_cksum = 0;
igmp->igmp_cksum = in_cksum(m, IGMP_MINLEN);
m->m_data -= sizeof(struct ip);
m->m_len += sizeof(struct ip);
- m->m_pkthdr.ph_rtableid = ifp->if_rdomain;
- imo.imo_ifidx = inm->inm_ifidx;
+ m->m_pkthdr.ph_rtableid = pkt->ipi_rdomain;
+ imo.imo_ifidx = pkt->ipi_ifidx;
imo.imo_ttl = 1;
/*
@@ -712,7 +743,7 @@ igmp_sendpkt(struct ifnet *ifp, struct i
* router, so that the process-level routing daemon can hear it.
*/
#ifdef MROUTING
- imo.imo_loop = (ip_mrouter[ifp->if_rdomain] != NULL);
+ imo.imo_loop = (ip_mrouter[pkt->ipi_rdomain] != NULL);
#else
imo.imo_loop = 0;
#endif /* MROUTING */
Index: netinet/igmp_var.h
===================================================================
RCS file: /data/mirror/openbsd/cvs/src/sys/netinet/igmp_var.h,v
diff -u -p -r1.16 igmp_var.h
--- netinet/igmp_var.h 2 Mar 2025 21:28:32 -0000 1.16
+++ netinet/igmp_var.h 3 Jan 2026 14:31:34 -0000
@@ -105,12 +105,26 @@ igmpstat_inc(enum igmpstat_counters c)
*/
#define IGMP_RANDOM_DELAY(X) (arc4random_uniform(X) + 1)
+struct igmp_pktinfo {
+ STAILQ_ENTRY(igmp_pktinfo) ipi_list;
+ struct in_addr ipi_addr;
+ unsigned int ipi_rdomain;
+ unsigned int ipi_ifidx;
+ int ipi_type;
+};
+STAILQ_HEAD(igmp_pktlist, igmp_pktinfo);
+
void igmp_init(void);
int igmp_input(struct mbuf **, int *, int, int, struct netstack *);
-void igmp_joingroup(struct in_multi *, struct ifnet *);
-void igmp_leavegroup(struct in_multi *, struct ifnet *);
+void igmp_joingroup(struct in_multi *, struct ifnet *,
+ struct igmp_pktinfo *);
+void igmp_leavegroup(struct in_multi *, struct ifnet *,
+ struct igmp_pktinfo *);
void igmp_fasttimo(void);
void igmp_slowtimo(void);
int igmp_sysctl(int *, u_int, void *, size_t *, void *, size_t);
+void igmp_sendpkt(struct igmp_pktinfo *);
+
#endif /* _KERNEL */
+
#endif /* _NETINET_IGMP_VAR_H_ */
Index: netinet/in.c
===================================================================
RCS file: /data/mirror/openbsd/cvs/src/sys/netinet/in.c,v
diff -u -p -r1.192 in.c
--- netinet/in.c 3 Jan 2026 14:10:04 -0000 1.192
+++ netinet/in.c 3 Jan 2026 14:31:34 -0000
@@ -853,7 +853,7 @@ in_lookupmulti(const struct in_addr *add
struct in_multi *inm = NULL;
struct ifmaddr *ifma;
- NET_ASSERT_LOCKED();
+ rw_assert_anylock(&ifp->if_maddrlock);
TAILQ_FOREACH(ifma, &ifp->if_maddrlist, ifma_list) {
if (ifma->ifma_addr->sa_family == AF_INET &&
@@ -871,54 +871,70 @@ in_lookupmulti(const struct in_addr *add
struct in_multi *
in_addmulti(const struct in_addr *addr, struct ifnet *ifp)
{
- struct in_multi *inm;
+ struct in_multi *inm, *new_inm = NULL;
+ struct igmp_pktinfo pkt;
struct ifreq ifr;
/*
* See if address already in list.
*/
+ rw_enter_write(&ifp->if_maddrlock);
inm = in_lookupmulti(addr, ifp);
- if (inm != NULL) {
- /*
- * Found it; just increment the reference count.
- */
- refcnt_take(&inm->inm_refcnt);
- } else {
- /*
- * New address; allocate a new multicast record
- * and link it into the interface's multicast list.
- */
- inm = malloc(sizeof(*inm), M_IPMADDR, M_WAITOK | M_ZERO);
- inm->inm_sin.sin_len = sizeof(struct sockaddr_in);
- inm->inm_sin.sin_family = AF_INET;
- inm->inm_sin.sin_addr = *addr;
- refcnt_init_trace(&inm->inm_refcnt, DT_REFCNT_IDX_IFMADDR);
- inm->inm_ifidx = ifp->if_index;
- inm->inm_ifma.ifma_addr = sintosa(&inm->inm_sin);
+ if (inm != NULL)
+ goto found;
+ rw_exit_write(&ifp->if_maddrlock);
- /*
- * Ask the network driver to update its multicast reception
- * filter appropriately for the new address.
- */
- memset(&ifr, 0, sizeof(ifr));
- memcpy(&ifr.ifr_addr, &inm->inm_sin, sizeof(inm->inm_sin));
- KERNEL_LOCK();
- if ((*ifp->if_ioctl)(ifp, SIOCADDMULTI,(caddr_t)&ifr) != 0) {
- KERNEL_UNLOCK();
- free(inm, M_IPMADDR, sizeof(*inm));
- return (NULL);
- }
+ /*
+ * New address; allocate a new multicast record
+ * and link it into the interface's multicast list.
+ */
+ new_inm = malloc(sizeof(*inm), M_IPMADDR, M_WAITOK | M_ZERO);
+
+ /*
+ * Ask the network driver to update its multicast reception
+ * filter appropriately for the new address.
+ */
+ memset(&ifr, 0, sizeof(ifr));
+ satosin(&ifr.ifr_addr)->sin_len = sizeof(struct sockaddr_in);
+ satosin(&ifr.ifr_addr)->sin_family = AF_INET;
+ satosin(&ifr.ifr_addr)->sin_addr = *addr;
+ KERNEL_LOCK();
+ if ((*ifp->if_ioctl)(ifp, SIOCADDMULTI,(caddr_t)&ifr) != 0) {
KERNEL_UNLOCK();
+ goto out;
+ }
+ KERNEL_UNLOCK();
- TAILQ_INSERT_HEAD(&ifp->if_maddrlist, &inm->inm_ifma,
- ifma_list);
+ rw_enter_write(&ifp->if_maddrlock);
+ /* check again after unlock and lock */
+ inm = in_lookupmulti(addr, ifp);
+ if (inm != NULL)
+ goto found;
+ inm = new_inm;
+ inm->inm_sin.sin_len = sizeof(struct sockaddr_in);
+ inm->inm_sin.sin_family = AF_INET;
+ inm->inm_sin.sin_addr = *addr;
+ refcnt_init_trace(&inm->inm_refcnt, DT_REFCNT_IDX_IFMADDR);
+ inm->inm_ifidx = ifp->if_index;
+ inm->inm_ifma.ifma_addr = sintosa(&inm->inm_sin);
- /*
- * Let IGMP know that we have joined a new IP multicast group.
- */
- igmp_joingroup(inm, ifp);
- }
+ /*
+ * Let IGMP know that we have joined a new IP multicast group.
+ */
+ TAILQ_INSERT_HEAD(&ifp->if_maddrlist, &inm->inm_ifma, ifma_list);
+ pkt.ipi_ifidx = 0;
+ igmp_joingroup(inm, ifp, &pkt);
+ rw_exit_write(&ifp->if_maddrlock);
+
+ if (pkt.ipi_ifidx)
+ igmp_sendpkt(&pkt);
+ return (inm);
+ found:
+ refcnt_take(&inm->inm_refcnt);
+ rw_exit_write(&ifp->if_maddrlock);
+ out:
+ free(new_inm, M_IPMADDR, sizeof(*inm));
return (inm);
}
@@ -928,21 +944,27 @@ in_addmulti(const struct in_addr *addr,
void
in_delmulti(struct in_multi *inm)
{
+ struct igmp_pktinfo pkt;
struct ifreq ifr;
struct ifnet *ifp;
- NET_ASSERT_LOCKED();
-
if (refcnt_rele(&inm->inm_refcnt) == 0)
return;
ifp = if_get(inm->inm_ifidx);
if (ifp != NULL) {
+ rw_enter_write(&ifp->if_maddrlock);
/*
* No remaining claims to this record; let IGMP know that
* we are leaving the multicast group.
*/
- igmp_leavegroup(inm, ifp);
+ pkt.ipi_ifidx = 0;
+ igmp_leavegroup(inm, ifp, &pkt);
+ TAILQ_REMOVE(&ifp->if_maddrlist, &inm->inm_ifma, ifma_list);
+ rw_exit_write(&ifp->if_maddrlock);
+
+ if (pkt.ipi_ifidx)
+ igmp_sendpkt(&pkt);
/*
* Notify the network driver to update its multicast
@@ -956,9 +978,8 @@ in_delmulti(struct in_multi *inm)
(*ifp->if_ioctl)(ifp, SIOCDELMULTI, (caddr_t)&ifr);
KERNEL_UNLOCK();
- TAILQ_REMOVE(&ifp->if_maddrlist, &inm->inm_ifma, ifma_list);
+ if_put(ifp);
}
- if_put(ifp);
free(inm, M_IPMADDR, sizeof(*inm));
}
@@ -973,8 +994,10 @@ in_hasmulti(const struct in_addr *addr,
struct in_multi *inm;
int joined;
+ rw_enter_read(&ifp->if_maddrlock);
inm = in_lookupmulti(addr, ifp);
joined = (inm != NULL);
+ rw_exit_read(&ifp->if_maddrlock);
return (joined);
}
Index: netinet/in_var.h
===================================================================
RCS file: /data/mirror/openbsd/cvs/src/sys/netinet/in_var.h,v
diff -u -p -r1.46 in_var.h
--- netinet/in_var.h 3 Jan 2026 14:10:04 -0000 1.46
+++ netinet/in_var.h 3 Jan 2026 14:22:23 -0000
@@ -35,6 +35,12 @@
#ifndef _NETINET_IN_VAR_H_
#define _NETINET_IN_VAR_H_
+/*
+ * Locks used to protect struct members in this file:
+ * I immutable after creation
+ * m multicast if_maddrlock rwlock of parent interface
+ */
+
#include <sys/queue.h>
#ifdef _KERNEL
@@ -87,11 +93,11 @@ struct in_multi {
#define inm_refcnt inm_ifma.ifma_refcnt
#define inm_ifidx inm_ifma.ifma_ifidx
- struct sockaddr_in inm_sin; /* IPv4 multicast address */
+ struct sockaddr_in inm_sin; /* [I] IPv4 multicast address */
#define inm_addr inm_sin.sin_addr
- u_int inm_state; /* state of membership */
- u_int inm_timer; /* IGMP membership report timer */
+ u_int inm_state; /* [m] state of membership */
+ u_int inm_timer; /* [m] IGMP membership report */
struct router_info *inm_rti; /* router version info */
};
Index: netinet6/in6.c
===================================================================
RCS file: /data/mirror/openbsd/cvs/src/sys/netinet6/in6.c,v
diff -u -p -r1.277 in6.c
--- netinet6/in6.c 3 Jan 2026 14:10:04 -0000 1.277
+++ netinet6/in6.c 3 Jan 2026 14:54:27 -0000
@@ -1007,7 +1007,7 @@ in6_lookupmulti(const struct in6_addr *a
struct in6_multi *in6m = NULL;
struct ifmaddr *ifma;
- NET_ASSERT_LOCKED();
+ rw_assert_anylock(&ifp->if_maddrlock);
TAILQ_FOREACH(ifma, &ifp->if_maddrlist, ifma_list) {
if (ifma->ifma_addr->sa_family == AF_INET6 &&
@@ -1026,62 +1026,75 @@ in6_lookupmulti(const struct in6_addr *a
struct in6_multi *
in6_addmulti(const struct in6_addr *addr, struct ifnet *ifp, int *errorp)
{
+ struct in6_multi *in6m, *new_in6m = NULL;
+ struct mld6_pktinfo pkt;
struct in6_ifreq ifr;
- struct in6_multi *in6m;
-
- NET_ASSERT_LOCKED();
*errorp = 0;
/*
* See if address already in list.
*/
+ rw_enter_write(&ifp->if_maddrlock);
in6m = in6_lookupmulti(addr, ifp);
- if (in6m != NULL) {
- /*
- * Found it; just increment the reference count.
- */
- refcnt_take(&in6m->in6m_refcnt);
- } else {
- /*
- * New address; allocate a new multicast record
- * and link it into the interface's multicast list.
- */
- in6m = malloc(sizeof(*in6m), M_IPMADDR, M_NOWAIT | M_ZERO);
- if (in6m == NULL) {
- *errorp = ENOBUFS;
- return (NULL);
- }
+ if (in6m != NULL)
+ goto found;
+ rw_exit_write(&ifp->if_maddrlock);
- in6m->in6m_sin.sin6_len = sizeof(struct sockaddr_in6);
- in6m->in6m_sin.sin6_family = AF_INET6;
- in6m->in6m_sin.sin6_addr = *addr;
- refcnt_init_trace(&in6m->in6m_refcnt, DT_REFCNT_IDX_IFMADDR);
- in6m->in6m_ifidx = ifp->if_index;
- in6m->in6m_ifma.ifma_addr = sin6tosa(&in6m->in6m_sin);
+ /*
+ * New address; allocate a new multicast record
+ * and link it into the interface's multicast list.
+ */
+ new_in6m = malloc(sizeof(*in6m), M_IPMADDR, M_NOWAIT | M_ZERO);
+ if (new_in6m == NULL) {
+ *errorp = ENOBUFS;
+ return (NULL);
+ }
- /*
- * Ask the network driver to update its multicast reception
- * filter appropriately for the new address.
- */
- memcpy(&ifr.ifr_addr, &in6m->in6m_sin, sizeof(in6m->in6m_sin));
- KERNEL_LOCK();
- *errorp = (*ifp->if_ioctl)(ifp, SIOCADDMULTI, (caddr_t)&ifr);
- KERNEL_UNLOCK();
- if (*errorp) {
- free(in6m, M_IPMADDR, sizeof(*in6m));
- return (NULL);
- }
+ /*
+ * Ask the network driver to update its multicast reception
+ * filter appropriately for the new address.
+ */
+ memset(&ifr, 0, sizeof(ifr));
+ ifr.ifr_addr.sin6_len = sizeof(struct sockaddr_in6);
+ ifr.ifr_addr.sin6_family = AF_INET6;
+ ifr.ifr_addr.sin6_addr = *addr;
+ KERNEL_LOCK();
+ *errorp = (*ifp->if_ioctl)(ifp, SIOCADDMULTI, (caddr_t)&ifr);
+ KERNEL_UNLOCK();
+ if (*errorp)
+ goto out;
+
+ rw_enter_write(&ifp->if_maddrlock);
+ /* check again after unlock and lock */
+ in6m = in6_lookupmulti(addr, ifp);
+ if (in6m != NULL)
+ goto found;
+ in6m = new_in6m;
+ in6m->in6m_sin.sin6_len = sizeof(struct sockaddr_in6);
+ in6m->in6m_sin.sin6_family = AF_INET6;
+ in6m->in6m_sin.sin6_addr = *addr;
+ refcnt_init_trace(&in6m->in6m_refcnt, DT_REFCNT_IDX_IFMADDR);
+ in6m->in6m_ifidx = ifp->if_index;
+ in6m->in6m_ifma.ifma_addr = sin6tosa(&in6m->in6m_sin);
+
+ /*
+ * Let MLD6 know that we have joined a new IP6 multicast group.
+ */
+ TAILQ_INSERT_HEAD(&ifp->if_maddrlist, &in6m->in6m_ifma, ifma_list);
+ pkt.mpi_ifidx = 0;
+ mld6_start_listening(in6m, ifp, &pkt);
+ rw_exit_write(&ifp->if_maddrlock);
- TAILQ_INSERT_HEAD(&ifp->if_maddrlist, &in6m->in6m_ifma,
- ifma_list);
+ if (pkt.mpi_ifidx)
+ mld6_sendpkt(&pkt);
- /*
- * Let MLD6 know that we have joined a new IP6 multicast
- * group.
- */
- mld6_start_listening(in6m);
- }
+ return (in6m);
+ found:
+ refcnt_take(&in6m->in6m_refcnt);
+ rw_exit_write(&ifp->if_maddrlock);
+ out:
+ free(new_in6m, M_IPMADDR, sizeof(*in6m));
return (in6m);
}
@@ -1091,39 +1104,44 @@ in6_addmulti(const struct in6_addr *addr
void
in6_delmulti(struct in6_multi *in6m)
{
+ struct mld6_pktinfo pkt;
struct in6_ifreq ifr;
struct ifnet *ifp;
- NET_ASSERT_LOCKED();
+ if (refcnt_rele(&in6m->in6m_refcnt) == 0)
+ return;
- if (refcnt_rele(&in6m->in6m_refcnt) != 0) {
+ ifp = if_get(in6m->in6m_ifidx);
+ if (ifp != NULL) {
+ rw_enter_write(&ifp->if_maddrlock);
/*
* No remaining claims to this record; let MLD6 know
* that we are leaving the multicast group.
*/
- mld6_stop_listening(in6m);
- ifp = if_get(in6m->in6m_ifidx);
+ pkt.mpi_ifidx = 0;
+ mld6_stop_listening(in6m, ifp, &pkt);
+ TAILQ_REMOVE(&ifp->if_maddrlist, &in6m->in6m_ifma, ifma_list);
+ rw_exit_write(&ifp->if_maddrlock);
+
+ if (pkt.mpi_ifidx)
+ mld6_sendpkt(&pkt);
/*
* Notify the network driver to update its multicast
* reception filter.
*/
- if (ifp != NULL) {
- bzero(&ifr.ifr_addr, sizeof(struct sockaddr_in6));
- ifr.ifr_addr.sin6_len = sizeof(struct sockaddr_in6);
- ifr.ifr_addr.sin6_family = AF_INET6;
- ifr.ifr_addr.sin6_addr = in6m->in6m_addr;
- KERNEL_LOCK();
- (*ifp->if_ioctl)(ifp, SIOCDELMULTI, (caddr_t)&ifr);
- KERNEL_UNLOCK();
+ memset(&ifr, 0, sizeof(ifr));
+ ifr.ifr_addr.sin6_len = sizeof(struct sockaddr_in6);
+ ifr.ifr_addr.sin6_family = AF_INET6;
+ ifr.ifr_addr.sin6_addr = in6m->in6m_addr;
+ KERNEL_LOCK();
+ (*ifp->if_ioctl)(ifp, SIOCDELMULTI, (caddr_t)&ifr);
+ KERNEL_UNLOCK();
- TAILQ_REMOVE(&ifp->if_maddrlist, &in6m->in6m_ifma,
- ifma_list);
- }
if_put(ifp);
-
- free(in6m, M_IPMADDR, sizeof(*in6m));
}
+
+ free(in6m, M_IPMADDR, sizeof(*in6m));
}
/*
@@ -1136,8 +1154,10 @@ in6_hasmulti(const struct in6_addr *addr
struct in6_multi *in6m;
int joined;
+ rw_enter_read(&ifp->if_maddrlock);
in6m = in6_lookupmulti(addr, ifp);
joined = (in6m != NULL);
+ rw_exit_read(&ifp->if_maddrlock);
return (joined);
}
Index: netinet6/in6_var.h
===================================================================
RCS file: /data/mirror/openbsd/cvs/src/sys/netinet6/in6_var.h,v
diff -u -p -r1.84 in6_var.h
--- netinet6/in6_var.h 3 Jan 2026 14:10:04 -0000 1.84
+++ netinet6/in6_var.h 3 Jan 2026 14:22:23 -0000
@@ -65,6 +65,12 @@
#define _NETINET6_IN6_VAR_H_
/*
+ * Locks used to protect struct members in this file:
+ * I immutable after creation
+ * m multicast if_maddrlock rwlock of parent interface
+ */
+
+/*
* Interface address, Internet version. One of these structures
* is allocated for each interface with an Internet address.
* The ifaddr structure contains the protocol-independent part
@@ -316,11 +322,11 @@ struct in6_multi {
#define in6m_refcnt in6m_ifma.ifma_refcnt
#define in6m_ifidx in6m_ifma.ifma_ifidx
- struct sockaddr_in6 in6m_sin; /* IPv6 multicast address */
+ struct sockaddr_in6 in6m_sin; /* [I] IPv6 multicast address */
#define in6m_addr in6m_sin.sin6_addr
- u_int in6m_state; /* state of membership */
- u_int in6m_timer; /* MLD6 membership report timer */
+ u_int in6m_state; /* [m] state of membership */
+ u_int in6m_timer; /* [m] MLD6 membership report */
};
static __inline struct in6_multi *
Index: netinet6/mld6.c
===================================================================
RCS file: /data/mirror/openbsd/cvs/src/sys/netinet6/mld6.c,v
diff -u -p -r1.72 mld6.c
--- netinet6/mld6.c 3 Jan 2026 14:10:04 -0000 1.72
+++ netinet6/mld6.c 3 Jan 2026 14:57:38 -0000
@@ -86,7 +86,6 @@ static struct ip6_pktopts ip6_opts;
int mld6_timers_are_running; /* [a] shortcut for fast timer */
int mld6_checktimer(struct ifnet *);
-static void mld6_sendpkt(struct in6_multi *, int, const struct in6_addr *);
void
mld6_init(void)
@@ -112,12 +111,15 @@ mld6_init(void)
}
void
-mld6_start_listening(struct in6_multi *in6m)
+mld6_start_listening(struct in6_multi *in6m, struct ifnet *ifp,
+ struct mld6_pktinfo *pkt)
{
/* XXX: These are necessary for KAME's link-local hack */
struct in6_addr all_nodes = IN6ADDR_LINKLOCAL_ALLNODES_INIT;
int running = 0;
+ rw_assert_wrlock(&ifp->if_maddrlock);
+
/*
* RFC2710 page 10:
* The node never sends a Report or Done for the link-scope all-nodes
@@ -132,10 +134,12 @@ mld6_start_listening(struct in6_multi *i
in6m->in6m_timer = 0;
in6m->in6m_state = MLD_OTHERLISTENER;
} else {
- mld6_sendpkt(in6m, MLD_LISTENER_REPORT, NULL);
+ pkt->mpi_addr = in6m->in6m_addr;
+ pkt->mpi_rdomain = ifp->if_rdomain;
+ pkt->mpi_ifidx = in6m->in6m_ifidx;
+ pkt->mpi_type = MLD_LISTENER_REPORT;
in6m->in6m_timer =
- MLD_RANDOM_DELAY(MLD_V1_MAX_RI *
- PR_FASTHZ);
+ MLD_RANDOM_DELAY(MLD_V1_MAX_RI * PR_FASTHZ);
in6m->in6m_state = MLD_IREPORTEDLAST;
running = 1;
}
@@ -147,12 +151,15 @@ mld6_start_listening(struct in6_multi *i
}
void
-mld6_stop_listening(struct in6_multi *in6m)
+mld6_stop_listening(struct in6_multi *in6m, struct ifnet *ifp,
+ struct mld6_pktinfo *pkt)
{
/* XXX: These are necessary for KAME's link-local hack */
struct in6_addr all_nodes = IN6ADDR_LINKLOCAL_ALLNODES_INIT;
struct in6_addr all_routers = IN6ADDR_LINKLOCAL_ALLROUTERS_INIT;
+ rw_assert_anylock(&ifp->if_maddrlock);
+
all_nodes.s6_addr16[1] = htons(in6m->in6m_ifidx);
/* XXX: necessary when mrouting */
all_routers.s6_addr16[1] = htons(in6m->in6m_ifidx);
@@ -160,8 +167,12 @@ mld6_stop_listening(struct in6_multi *in
if (in6m->in6m_state == MLD_IREPORTEDLAST &&
(!IN6_ARE_ADDR_EQUAL(&in6m->in6m_addr, &all_nodes)) &&
__IPV6_ADDR_MC_SCOPE(&in6m->in6m_addr) >
- __IPV6_ADDR_SCOPE_INTFACELOCAL)
- mld6_sendpkt(in6m, MLD_LISTENER_DONE, &all_routers);
+ __IPV6_ADDR_SCOPE_INTFACELOCAL) {
+ pkt->mpi_addr = all_routers;
+ pkt->mpi_rdomain = ifp->if_rdomain;
+ pkt->mpi_ifidx = in6m->in6m_ifidx;
+ pkt->mpi_type = MLD_LISTENER_DONE;
+ }
}
void
@@ -254,6 +265,7 @@ mld6_input(struct mbuf *m, int off)
timer = 1;
all_nodes.s6_addr16[1] = htons(ifp->if_index);
+ rw_enter_write(&ifp->if_maddrlock);
TAILQ_FOREACH(ifma, &ifp->if_maddrlist, ifma_list) {
if (ifma->ifma_addr->sa_family != AF_INET6)
continue;
@@ -269,8 +281,13 @@ mld6_input(struct mbuf *m, int off)
{
if (timer == 0) {
/* send a report immediately */
- mld6_sendpkt(in6m, MLD_LISTENER_REPORT,
- NULL);
+ struct mld6_pktinfo pkt;
+
+ pkt.mpi_addr = in6m->in6m_addr;
+ pkt.mpi_rdomain = ifp->if_rdomain;
+ pkt.mpi_ifidx = in6m->in6m_ifidx;
+ pkt.mpi_type = MLD_LISTENER_REPORT;
+ mld6_sendpkt(&pkt);
in6m->in6m_timer = 0; /* reset timer */
in6m->in6m_state = MLD_IREPORTEDLAST;
} else if (in6m->in6m_timer == 0 || /* idle */
@@ -281,6 +298,7 @@ mld6_input(struct mbuf *m, int off)
}
}
}
+ rw_exit_write(&ifp->if_maddrlock);
if (IN6_IS_ADDR_MC_LINKLOCAL(&mldh->mld_addr))
mldh->mld_addr.s6_addr16[1] = 0; /* XXX */
@@ -308,11 +326,13 @@ mld6_input(struct mbuf *m, int off)
* If we belong to the group being reported, stop
* our timer for that group.
*/
+ rw_enter_write(&ifp->if_maddrlock);
in6m = in6_lookupmulti(&mldh->mld_addr, ifp);
if (in6m) {
in6m->in6m_timer = 0; /* transit to idle state */
in6m->in6m_state = MLD_OTHERLISTENER; /* clear flag */
}
+ rw_exit_write(&ifp->if_maddrlock);
if (IN6_IS_ADDR_MC_LINKLOCAL(&mldh->mld_addr))
mldh->mld_addr.s6_addr16[1] = 0; /* XXX */
@@ -355,7 +375,7 @@ mld6_fasttimo(void)
return;
membar_consumer();
- NET_LOCK();
+ NET_LOCK_SHARED();
TAILQ_FOREACH(ifp, &ifnetlist, if_list) {
if (mld6_checktimer(ifp))
@@ -365,7 +385,7 @@ mld6_fasttimo(void)
membar_producer();
atomic_store_int(&mld6_timers_are_running, running);
- NET_UNLOCK();
+ NET_UNLOCK_SHARED();
}
int
@@ -373,10 +393,11 @@ mld6_checktimer(struct ifnet *ifp)
{
struct in6_multi *in6m;
struct ifmaddr *ifma;
+ struct mld6_pktlist pktlist;
int running = 0;
- NET_ASSERT_LOCKED();
-
+ rw_enter_write(&ifp->if_maddrlock);
+ STAILQ_INIT(&pktlist);
TAILQ_FOREACH(ifma, &ifp->if_maddrlist, ifma_list) {
if (ifma->ifma_addr->sa_family != AF_INET6)
continue;
@@ -384,18 +405,37 @@ mld6_checktimer(struct ifnet *ifp)
if (in6m->in6m_timer == 0) {
/* do nothing */
} else if (--in6m->in6m_timer == 0) {
- mld6_sendpkt(in6m, MLD_LISTENER_REPORT, NULL);
+ struct mld6_pktinfo *pkt;
+
in6m->in6m_state = MLD_IREPORTEDLAST;
+ pkt = malloc(sizeof(*pkt), M_MRTABLE, M_NOWAIT);
+ if (pkt == NULL)
+ continue;
+ pkt->mpi_addr = in6m->in6m_addr;
+ pkt->mpi_rdomain = ifp->if_rdomain;
+ pkt->mpi_ifidx = in6m->in6m_ifidx;
+ pkt->mpi_type = MLD_LISTENER_REPORT;
+ STAILQ_INSERT_TAIL(&pktlist, pkt, mpi_list);
} else {
running = 1;
}
}
+ rw_exit_write(&ifp->if_maddrlock);
+
+ while (!STAILQ_EMPTY(&pktlist)) {
+ struct mld6_pktinfo *pkt;
+
+ pkt = STAILQ_FIRST(&pktlist);
+ STAILQ_REMOVE_HEAD(&pktlist, mpi_list);
+ mld6_sendpkt(pkt);
+ free(pkt, M_MRTABLE, sizeof(*pkt));
+ }
return (running);
}
-static void
-mld6_sendpkt(struct in6_multi *in6m, int type, const struct in6_addr *dst)
+void
+mld6_sendpkt(const struct mld6_pktinfo *pkt)
{
struct mbuf *mh, *md;
struct mld_hdr *mldh;
@@ -405,7 +445,7 @@ mld6_sendpkt(struct in6_multi *in6m, int
struct ifnet *ifp;
int ignflags;
- ifp = if_get(in6m->in6m_ifidx);
+ ifp = if_get(pkt->mpi_ifidx);
if (ifp == NULL)
return;
@@ -441,8 +481,7 @@ mld6_sendpkt(struct in6_multi *in6m, int
}
mh->m_next = md;
- mh->m_pkthdr.ph_ifidx = 0;
- mh->m_pkthdr.ph_rtableid = ifp->if_rdomain;
+ mh->m_pkthdr.ph_rtableid = pkt->mpi_rdomain;
mh->m_pkthdr.len = sizeof(struct ip6_hdr) + sizeof(struct mld_hdr);
mh->m_len = sizeof(struct ip6_hdr);
m_align(mh, sizeof(struct ip6_hdr));
@@ -456,25 +495,25 @@ mld6_sendpkt(struct in6_multi *in6m, int
ip6->ip6_nxt = IPPROTO_ICMPV6;
/* ip6_hlim will be set by im6o.im6o_hlim */
ip6->ip6_src = ia6 ? ia6->ia_addr.sin6_addr : in6addr_any;
- ip6->ip6_dst = dst ? *dst : in6m->in6m_addr;
+ ip6->ip6_dst = pkt->mpi_addr;
/* fill in the MLD header */
md->m_len = sizeof(struct mld_hdr);
mldh = mtod(md, struct mld_hdr *);
- mldh->mld_type = type;
+ mldh->mld_type = pkt->mpi_type;
mldh->mld_code = 0;
mldh->mld_cksum = 0;
/* XXX: we assume the function will not be called for query messages */
mldh->mld_maxdelay = 0;
mldh->mld_reserved = 0;
- mldh->mld_addr = in6m->in6m_addr;
+ mldh->mld_addr = pkt->mpi_addr;
if (IN6_IS_ADDR_MC_LINKLOCAL(&mldh->mld_addr))
mldh->mld_addr.s6_addr16[1] = 0; /* XXX */
mh->m_pkthdr.csum_flags |= M_ICMP_CSUM_OUT;
/* construct multicast option */
bzero(&im6o, sizeof(im6o));
- im6o.im6o_ifidx = ifp->if_index;
+ im6o.im6o_ifidx = pkt->mpi_ifidx;
im6o.im6o_hlim = 1;
/*
@@ -482,10 +521,10 @@ mld6_sendpkt(struct in6_multi *in6m, int
* router, so that the process-level routing daemon can hear it.
*/
#ifdef MROUTING
- im6o.im6o_loop = (ip6_mrouter[ifp->if_rdomain] != NULL);
+ im6o.im6o_loop = (ip6_mrouter[pkt->mpi_rdomain] != NULL);
#endif
if_put(ifp);
- icmp6stat_inc(icp6s_outhist + type);
+ icmp6stat_inc(icp6s_outhist + pkt->mpi_type);
ip6_output(mh, &ip6_opts, NULL, ia6 ? 0 : IPV6_UNSPECSRC, &im6o, NULL);
}
Index: netinet6/mld6_var.h
===================================================================
RCS file: /data/mirror/openbsd/cvs/src/sys/netinet6/mld6_var.h,v
diff -u -p -r1.9 mld6_var.h
--- netinet6/mld6_var.h 3 Jan 2026 14:10:04 -0000 1.9
+++ netinet6/mld6_var.h 3 Jan 2026 14:51:39 -0000
@@ -43,11 +43,24 @@
#define MLD_OTHERLISTENER 0
#define MLD_IREPORTEDLAST 1
+struct mld6_pktinfo {
+ STAILQ_ENTRY(mld6_pktinfo) mpi_list;
+ struct in6_addr mpi_addr;
+ unsigned int mpi_rdomain;
+ unsigned int mpi_ifidx;
+ int mpi_type;
+};
+STAILQ_HEAD(mld6_pktlist, mld6_pktinfo);
+
void mld6_init(void);
void mld6_input(struct mbuf *, int);
-void mld6_start_listening(struct in6_multi *);
-void mld6_stop_listening(struct in6_multi *);
+void mld6_start_listening(struct in6_multi *, struct ifnet *,
+ struct mld6_pktinfo *);
+void mld6_stop_listening(struct in6_multi *, struct ifnet *,
+ struct mld6_pktinfo *);
void mld6_fasttimo(void);
+void mld6_sendpkt(const struct mld6_pktinfo *);
+
#endif /* _KERNEL */
#endif /* _NETINET6_MLD6_VAR_H_ */
unlock igmp and mld6 fast timer