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Push netlock down to mrt_sysctl_vif()
On Fri, Jul 18, 2025 at 09:06:04PM +0300, Vitaliy Makkoveev wrote:
> On Fri, Jul 18, 2025 at 04:06:31PM +0200, Alexander Bluhm wrote:
> > On Thu, Jul 17, 2025 at 09:32:12PM +0300, Vitaliy Makkoveev wrote:
> > > Link the network interfaces to the temporary `if_tmplist' list protected
> > > with `if_tmplist_lock' rwlock(9). This moves copyuot() out of exclusive
> > > netlock and allows to relax it to shared netlock.
> > >
> > > ip_sysctl() became mp-safe, so mark it as PR_MPSYSCTL.
> > >
> > > Note, this time we have a small amount of places where we use
> > > `if_tmplist' to userland delivery. I could rework them to use iterator,
> > > so the copyout(9) will be done lockless. The null interface index is
> > > invalid, so the special iterator does not require to add something new
> > > to the ifnet structure.
> >
> > A return (error) is missing, see below.
> >
>
> Thanks for pointing.
OK bluhm@
> Index: sys/net/if.c
> ===================================================================
> RCS file: /cvs/src/sys/net/if.c,v
> retrieving revision 1.738
> diff -u -p -r1.738 if.c
> --- sys/net/if.c 18 Jul 2025 15:44:44 -0000 1.738
> +++ sys/net/if.c 18 Jul 2025 18:04:07 -0000
> @@ -187,8 +187,6 @@ struct softnet *
> * if_get(0) returns NULL.
> */
>
> -struct ifnet *if_ref(struct ifnet *);
> -
> /*
> * struct if_idxmap
> *
> Index: sys/net/if.h
> ===================================================================
> RCS file: /cvs/src/sys/net/if.h,v
> retrieving revision 1.219
> diff -u -p -r1.219 if.h
> --- sys/net/if.h 9 May 2025 03:12:36 -0000 1.219
> +++ sys/net/if.h 18 Jul 2025 18:04:07 -0000
> @@ -554,6 +554,7 @@ int if_delgroup(struct ifnet *, const ch
> void if_group_routechange(const struct sockaddr *, const struct sockaddr *);
> struct ifnet *if_unit(const char *);
> struct ifnet *if_get(unsigned int);
> +struct ifnet *if_ref(struct ifnet *);
> void if_put(struct ifnet *);
> void ifnewlladdr(struct ifnet *);
> void if_congestion(void);
> Index: sys/net/if_var.h
> ===================================================================
> RCS file: /cvs/src/sys/net/if_var.h,v
> retrieving revision 1.138
> diff -u -p -r1.138 if_var.h
> --- sys/net/if_var.h 25 Jun 2025 20:26:32 -0000 1.138
> +++ sys/net/if_var.h 18 Jul 2025 18:04:07 -0000
> @@ -328,6 +328,7 @@ int niq_enqueue(struct niqueue *, struc
> #define sysctl_niq(_n, _l, _op, _olp, _np, _nl, _niq) \
> sysctl_mq((_n), (_l), (_op), (_olp), (_np), (_nl), &(_niq)->ni_q)
>
> +extern struct rwlock if_tmplist_lock;
> extern struct ifnet_head ifnetlist;
>
> void if_start(struct ifnet *);
> Index: sys/netinet/in_proto.c
> ===================================================================
> RCS file: /cvs/src/sys/netinet/in_proto.c,v
> retrieving revision 1.126
> diff -u -p -r1.126 in_proto.c
> --- sys/netinet/in_proto.c 8 Jul 2025 00:47:41 -0000 1.126
> +++ sys/netinet/in_proto.c 18 Jul 2025 18:04:07 -0000
> @@ -168,6 +168,7 @@ const struct protosw inetsw[] = {
> .pr_init = ip_init,
> .pr_slowtimo = ip_slowtimo,
> #ifndef SMALL_KERNEL
> + .pr_flags = PR_MPSYSCTL,
> .pr_sysctl = ip_sysctl
> #endif /* SMALL_KERNEL */
> },
> Index: sys/netinet/ip_input.c
> ===================================================================
> RCS file: /cvs/src/sys/netinet/ip_input.c,v
> retrieving revision 1.421
> diff -u -p -r1.421 ip_input.c
> --- sys/netinet/ip_input.c 17 Jul 2025 17:31:45 -0000 1.421
> +++ sys/netinet/ip_input.c 18 Jul 2025 18:04:07 -0000
> @@ -1807,10 +1807,7 @@ ip_sysctl(int *name, u_int namelen, void
> case IPCTL_MRTVIF:
> if (newp)
> return (EPERM);
> - NET_LOCK();
> - error = mrt_sysctl_vif(oldp, oldlenp);
> - NET_UNLOCK();
> - return (error);
> + return (mrt_sysctl_vif(oldp, oldlenp));
> #else
> case IPCTL_MRTPROTO:
> case IPCTL_MRTSTATS:
> Index: sys/netinet/ip_mroute.c
> ===================================================================
> RCS file: /cvs/src/sys/netinet/ip_mroute.c,v
> retrieving revision 1.149
> diff -u -p -r1.149 ip_mroute.c
> --- sys/netinet/ip_mroute.c 8 Jul 2025 00:47:41 -0000 1.149
> +++ sys/netinet/ip_mroute.c 18 Jul 2025 18:04:07 -0000
> @@ -360,18 +360,36 @@ get_vif_cnt(unsigned int rtableid, struc
> int
> mrt_sysctl_vif(void *oldp, size_t *oldlenp)
> {
> + TAILQ_HEAD(, ifnet) if_tmplist =
> + TAILQ_HEAD_INITIALIZER(if_tmplist);
> caddr_t where = oldp;
> size_t needed, given;
> struct ifnet *ifp;
> struct vif *vifp;
> struct vifinfo vinfo;
> + int error = 0;
>
> given = *oldlenp;
> needed = 0;
> memset(&vinfo, 0, sizeof vinfo);
> +
> + rw_enter_write(&if_tmplist_lock);
> + NET_LOCK_SHARED();
> +
> TAILQ_FOREACH(ifp, &ifnetlist, if_list) {
> - if ((vifp = (struct vif *)ifp->if_mcast) == NULL)
> + if (ifp->if_mcast != NULL) {
> + if_ref(ifp);
> + TAILQ_INSERT_TAIL(&if_tmplist, ifp, if_tmplist);
> + }
> + }
> + NET_UNLOCK_SHARED();
> +
> + TAILQ_FOREACH (ifp, &if_tmplist, if_tmplist) {
> + NET_LOCK_SHARED();
> + if ((vifp = (struct vif *)ifp->if_mcast) == NULL) {
> + NET_UNLOCK_SHARED();
> continue;
> + }
>
> vinfo.v_vifi = vifp->v_id;
> vinfo.v_flags = vifp->v_flags;
> @@ -382,17 +400,27 @@ mrt_sysctl_vif(void *oldp, size_t *oldle
> vinfo.v_pkt_out = vifp->v_pkt_out;
> vinfo.v_bytes_in = vifp->v_bytes_in;
> vinfo.v_bytes_out = vifp->v_bytes_out;
> + NET_UNLOCK_SHARED();
>
> needed += sizeof(vinfo);
> if (where && needed <= given) {
> - int error;
> -
> error = copyout(&vinfo, where, sizeof(vinfo));
> if (error)
> - return (error);
> + break;
> where += sizeof(vinfo);
> }
> }
> +
> + while ((ifp = TAILQ_FIRST(&if_tmplist))) {
> + TAILQ_REMOVE(&if_tmplist, ifp, if_tmplist);
> + if_put(ifp);
> + }
> +
> + rw_exit_write(&if_tmplist_lock);
> +
> + if (error)
> + return (error);
> +
> if (where) {
> *oldlenp = needed;
> if (given < needed)
>
Push netlock down to mrt_sysctl_vif()