[src/trunk]: src/sys/net Get rid of gre's deadlock-prone, one-off ifioctl loc...

[dyoung <dyoung%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/072ab91691eb
branches:  trunk
changeset: 770519:072ab91691eb
user:      dyoung <dyoung%NetBSD.org@localhost>
date:      Wed Oct 19 21:59:38 2011 +0000

description:
Get rid of gre's deadlock-prone, one-off ifioctl locking.  The standard
ifioctl locking will do.

diffstat:

 sys/net/if_gre.c |  68 +------------------------------------------------------
 1 files changed, 2 insertions(+), 66 deletions(-)

diffs (124 lines):

diff -r 89b2f4f7143b -r 072ab91691eb sys/net/if_gre.c
--- a/sys/net/if_gre.c  Wed Oct 19 21:29:51 2011 +0000
+++ b/sys/net/if_gre.c  Wed Oct 19 21:59:38 2011 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: if_gre.c,v 1.145 2011/05/24 16:37:49 joerg Exp $ */
+/*     $NetBSD: if_gre.c,v 1.146 2011/10/19 21:59:38 dyoung Exp $ */
 
 /*
  * Copyright (c) 1998, 2008 The NetBSD Foundation, Inc.
@@ -45,7 +45,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: if_gre.c,v 1.145 2011/05/24 16:37:49 joerg Exp $");
+__KERNEL_RCSID(0, "$NetBSD: if_gre.c,v 1.146 2011/10/19 21:59:38 dyoung Exp $");
 
 #include "opt_atalk.h"
 #include "opt_gre.h"
@@ -266,14 +266,6 @@
 
 /* Caller must hold sc->sc_mtx. */
 static void
-gre_wait(struct gre_softc *sc)
-{
-       sc->sc_waiters++;
-       cv_wait(&sc->sc_condvar, &sc->sc_mtx);
-       sc->sc_waiters--;
-}
-
-static void
 gre_fp_wait(struct gre_softc *sc)
 {
        sc->sc_fp_waiters++;
@@ -362,7 +354,6 @@
        if_attach(&sc->sc_if);
        if_alloc_sadl(&sc->sc_if);
        bpf_attach(&sc->sc_if, DLT_NULL, sizeof(uint32_t));
-       sc->sc_state = GRE_S_IDLE;
        return 0;
 }
 
@@ -378,23 +369,6 @@
        s = splnet();
        if_detach(ifp);
 
-       /* Some LWPs may still wait in gre_ioctl_lock(), however,
-        * no new LWP will enter gre_ioctl_lock(), because ifunit()
-        * cannot locate the interface any longer.
-        */
-       mutex_enter(&sc->sc_mtx);
-       GRE_DPRINTF(sc, "\n");
-       while (sc->sc_state != GRE_S_IDLE)
-               gre_wait(sc);
-       GRE_DPRINTF(sc, "\n");
-       sc->sc_state = GRE_S_DIE;
-       cv_broadcast(&sc->sc_condvar);
-       while (sc->sc_waiters > 0)
-               cv_wait(&sc->sc_condvar, &sc->sc_mtx);
-       /* At this point, no other LWP will access the gre_softc, so
-        * we can release the mutex.
-        */
-       mutex_exit(&sc->sc_mtx);
        GRE_DPRINTF(sc, "\n");
        /* Note that we must not hold the mutex while we call gre_reconf(). */
        gre_reconf(sc, NULL);
@@ -1242,39 +1216,6 @@
 }
 
 static int
-gre_ioctl_lock(struct gre_softc *sc)
-{
-       mutex_enter(&sc->sc_mtx);
-
-       while (sc->sc_state == GRE_S_IOCTL)
-               gre_wait(sc);
-
-       if (sc->sc_state != GRE_S_IDLE) {
-               cv_signal(&sc->sc_condvar);
-               mutex_exit(&sc->sc_mtx);
-               GRE_DPRINTF(sc, "\n");
-               return ENXIO;
-       }
-
-       sc->sc_state = GRE_S_IOCTL;
-
-       mutex_exit(&sc->sc_mtx);
-       return 0;
-}
-
-static void
-gre_ioctl_unlock(struct gre_softc *sc)
-{
-       mutex_enter(&sc->sc_mtx);
-
-       KASSERT(sc->sc_state == GRE_S_IOCTL);
-       sc->sc_state = GRE_S_IDLE;
-       cv_signal(&sc->sc_condvar);
-
-       mutex_exit(&sc->sc_mtx);
-}
-
-static int
 gre_ioctl(struct ifnet *ifp, const u_long cmd, void *data)
 {
        struct ifreq *ifr;
@@ -1308,10 +1249,6 @@
                break;
        }
 
-       if ((error = gre_ioctl_lock(sc)) != 0) {
-               GRE_DPRINTF(sc, "\n");
-               return error;
-       }
        s = splnet();
 
        sp0 = sc->sc_soparm;
@@ -1549,7 +1486,6 @@
 out:
        GRE_DPRINTF(sc, "\n");
        splx(s);
-       gre_ioctl_unlock(sc);
        return error;
 }