On Wed, May 03, 2023 at 12:22:16AM +0200, Alexander Bluhm wrote:
> Hi,
>
> Some checks in nd6_resolve() do not require kernel lock. The analog
> code for ARP has been unlocked in if_ether.c revision 1.250 since
> 2022/06/27 20:47:10.
Same diff here, thought I sent/committed that already.
OK kn if you want to go ahead, else I'll take an OK ;)
Soon (tm) the kernel lock will be replaced with the new nd6 mutex.
>
> ok?
>
> bluhm
>
> Index: netinet6/nd6.c
> ===
> RCS file: /data/mirror/openbsd/cvs/src/sys/netinet6/nd6.c,v
> retrieving revision 1.273
> diff -u -p -r1.273 nd6.c
> --- netinet6/nd6.c2 May 2023 06:06:13 - 1.273
> +++ netinet6/nd6.c2 May 2023 18:44:23 -
> @@ -1260,15 +1260,12 @@ nd6_resolve(struct ifnet *ifp, struct rt
> return (0);
> }
>
> - /* XXXSMP there is a MP race in nd6_resolve() */
> - KERNEL_LOCK();
> uptime = getuptime();
> rt = rt_getll(rt0);
>
> if (ISSET(rt->rt_flags, RTF_REJECT) &&
> (rt->rt_expire == 0 || rt->rt_expire > uptime)) {
> m_freem(m);
> - KERNEL_UNLOCK();
> return (rt == rt0 ? EHOSTDOWN : EHOSTUNREACH);
> }
>
> @@ -1291,6 +1288,11 @@ nd6_resolve(struct ifnet *ifp, struct rt
> goto bad;
> }
>
> + KERNEL_LOCK();
> + if (!ISSET(rt->rt_flags, RTF_LLINFO)) {
> + KERNEL_UNLOCK();
> + goto bad;
> + }
> ln = (struct llinfo_nd6 *)rt->rt_llinfo;
> KASSERT(ln != NULL);
>
> @@ -1321,6 +1323,8 @@ nd6_resolve(struct ifnet *ifp, struct rt
>* send the packet.
>*/
> if (ln->ln_state > ND6_LLINFO_INCOMPLETE) {
> + KERNEL_UNLOCK();
> +
> sdl = satosdl(rt->rt_gateway);
> if (sdl->sdl_alen != ETHER_ADDR_LEN) {
> char addr[INET6_ADDRSTRLEN];
> @@ -1332,7 +1336,6 @@ nd6_resolve(struct ifnet *ifp, struct rt
> }
>
> bcopy(LLADDR(sdl), desten, sdl->sdl_alen);
> - KERNEL_UNLOCK();
> return (0);
> }
>
> @@ -1374,7 +1377,6 @@ nd6_resolve(struct ifnet *ifp, struct rt
>
> bad:
> m_freem(m);
> - KERNEL_UNLOCK();
> return (EINVAL);
> }
>
>
