Don't take kernel lock on pipex(4) pppoe input. This extra serialization

is not required. In packet processing path we have shared netlock held,
but we do read-only access on per session `flags' and `ifindex'. We always
modify them from ioctl(2) path with exclusive netlock held. The rest of
pipex(4) session is immutable or uses per-session locks.

ok bluhm@

diff --git a/sys/net/if_ethersubr.c b/sys/net/if_ethersubr.c
index b460036..d49696c 100644 (file)
--- a/sys/net/if_ethersubr.c
+++ b/sys/net/if_ethersubr.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: if_ethersubr.c,v 1.280 2022/06/26 15:50:21 mvs Exp $  */
+/*     $OpenBSD: if_ethersubr.c,v 1.281 2022/06/26 21:19:53 mvs Exp $  */
 /*     $NetBSD: if_ethersubr.c,v 1.19 1996/05/07 02:40:30 thorpej Exp $        */
 
 /*
@@ -540,7 +540,6 @@ ether_input(struct ifnet *ifp, struct mbuf *m)
        case ETHERTYPE_PPPOE:
                if (m->m_flags & (M_MCAST | M_BCAST))
                        goto dropanyway;
-               KERNEL_LOCK();
 #ifdef PIPEX
                if (pipex_enable) {
                        struct pipex_session *session;
@@ -548,12 +547,12 @@ ether_input(struct ifnet *ifp, struct mbuf *m)
                        if ((session = pipex_pppoe_lookup_session(m)) != NULL) {
                                pipex_pppoe_input(m, session);
                                pipex_rele_session(session);
-                               KERNEL_UNLOCK();
                                return;
                        }
                        pipex_rele_session(session);
                }
 #endif
+               KERNEL_LOCK();
                if (etype == ETHERTYPE_PPPOEDISC)
                        pppoe_disc_input(m);
                else