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Lock down global variables in if_gre:

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- Add gre_mtx to protect global softc list.
- Hold gre_mtx over various list operations (insert, delete).
- Centralize if_gre interface teardown in gre_destroy(), and call this
  from modevent unload and gre_clone_destroy().
- Export gre_mtx to ip_gre.c, which walks the gre list to look up gre
  interfaces during encapsulation.  Add a wonking comment on how we need
  some sort of drain/reference count mechanism to keep gre references
  alive while in use and simultaneous destroy.

This commit does not lockdown softc data, which follows in a future
commit.
This commit is contained in:
Robert Watson 2004-03-22 16:04:43 +00:00
parent 7676d865bd
commit bdae44a844
3 changed files with 47 additions and 10 deletions
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43
sys/net/if_gre.c
View File

@ -91,6 +91,11 @@
#define GRENAME "gre"
/*
* gre_mtx protects all global variables in if_gre.c.
* XXX: gre_softc data not protected yet.
*/
struct mtx gre_mtx;
static MALLOC_DEFINE(M_GRE, GRENAME, "Generic Routing Encapsulation");
struct gre_softc_head gre_softc_list;
@ -149,6 +154,7 @@ static void
greattach(void)
{
mtx_init(&gre_mtx, "gre_mtx", NULL, MTX_DEF);
LIST_INIT(&gre_softc_list);
if_clone_attach(&gre_cloner);
}
@ -181,24 +187,35 @@ gre_clone_create(ifc, unit)
sc->wccp_ver = WCCP_V1;
if_attach(&sc->sc_if);
bpfattach(&sc->sc_if, DLT_NULL, sizeof(u_int32_t));
mtx_lock(&gre_mtx);
LIST_INSERT_HEAD(&gre_softc_list, sc, sc_list);
mtx_unlock(&gre_mtx);
return (0);
}
static void
gre_destroy(struct gre_softc *sc)
{
#ifdef INET
if (sc->encap != NULL)
encap_detach(sc->encap);
#endif
bpfdetach(&sc->sc_if);
if_detach(&sc->sc_if);
free(sc, M_GRE);
}
static void
gre_clone_destroy(ifp)
struct ifnet *ifp;
{
struct gre_softc *sc = ifp->if_softc;
#ifdef INET
if (sc->encap != NULL)
encap_detach(sc->encap);
#endif
mtx_lock(&gre_mtx);
LIST_REMOVE(sc, sc_list);
bpfdetach(ifp);
if_detach(ifp);
free(sc, M_GRE);
mtx_unlock(&gre_mtx);
gre_destroy(sc);
}
/*
@ -727,6 +744,7 @@ gre_in_cksum(u_int16_t *p, u_int len)
static int
gremodevent(module_t mod, int type, void *data)
{
struct gre_softc *sc;
switch (type) {
case MOD_LOAD:
@ -735,8 +753,15 @@ gremodevent(module_t mod, int type, void *data)
case MOD_UNLOAD:
if_clone_detach(&gre_cloner);
while (!LIST_EMPTY(&gre_softc_list))
gre_clone_destroy(&LIST_FIRST(&gre_softc_list)->sc_if);
mtx_lock(&gre_mtx);
while ((sc = LIST_FIRST(&gre_softc_list)) != NULL) {
LIST_REMOVE(sc, sc_list);
mtx_unlock(&gre_mtx);
gre_destroy(sc);
mtx_lock(&gre_mtx);
}
mtx_unlock(&gre_mtx);
mtx_destroy(&gre_mtx);
break;
}
return 0;

1
sys/net/if_gre.h
View File

@ -176,6 +176,7 @@ struct mobip_h {
#ifdef _KERNEL
LIST_HEAD(gre_softc_head, gre_softc);
extern struct mtx gre_mtx;
extern struct gre_softc_head gre_softc_list;
u_int16_t gre_in_cksum(u_int16_t *, u_int);

13
sys/netinet/ip_gre.c
View File

@ -314,6 +314,13 @@ gre_mobile_input(m, va_alist)
/*
* Find the gre interface associated with our src/dst/proto set.
*
* XXXRW: Need some sort of drain/refcount mechanism so that the softc
* reference remains valid after it's returned from gre_lookup(). Right
* now, I'm thinking it should be reference-counted with a gre_dropref()
* when the caller is done with the softc. This is complicated by how
* to handle destroying the gre softc; probably using a gre_drain() in
* in_gre.c during destroy.
*/
static struct gre_softc *
gre_lookup(m, proto)
@ -323,14 +330,18 @@ gre_lookup(m, proto)
struct ip *ip = mtod(m, struct ip *);
struct gre_softc *sc;
mtx_lock(&gre_mtx);
for (sc = LIST_FIRST(&gre_softc_list); sc != NULL;
sc = LIST_NEXT(sc, sc_list)) {
if ((sc->g_dst.s_addr == ip->ip_src.s_addr) &&
(sc->g_src.s_addr == ip->ip_dst.s_addr) &&
(sc->g_proto == proto) &&
((sc->sc_if.if_flags & IFF_UP) != 0))
((sc->sc_if.if_flags & IFF_UP) != 0)) {
mtx_unlock(&gre_mtx);
return (sc);
}
}
mtx_unlock(&gre_mtx);
return (NULL);
}