Now that we have a single refcounting mechanism for route entries, I'd
like to use atomic operations and grab the KERNEL_LOCK only if a CPU is
dropping the last reference on an entry.
Currently this only matters for MPLS. I intentionally use atomic_* ops
because I'd like to see be able to see if a counter goes negative.
For symmetry reasons I'm also moving the KERNEL_LOCK() inside rtalloc().
These two functions are my current targets.
Comments, oks?
Index: sys/net/route.c
===================================================================
RCS file: /cvs/src/sys/net/route.c,v
retrieving revision 1.258
diff -u -p -r1.258 route.c
--- sys/net/route.c 22 Oct 2015 17:19:38 -0000 1.258
+++ sys/net/route.c 22 Oct 2015 17:21:52 -0000
@@ -215,6 +215,7 @@ rtalloc(struct sockaddr *dst, int flags,
info.rti_info[RTAX_DST] = dst;
s = splsoftnet();
+ KERNEL_LOCK();
rt = rtable_match(tableid, dst);
if (rt != NULL) {
if ((rt->rt_flags & RTF_CLONING) && ISSET(flags, RT_RESOLVE)) {
@@ -236,6 +237,7 @@ miss:
if (ISSET(flags, RT_REPORT))
rt_missmsg(RTM_MISS, &info, 0, NULL, error, tableid);
}
+ KERNEL_UNLOCK();
splx(s);
return (rt);
}
@@ -337,7 +339,7 @@ rtalloc_mpath(struct sockaddr *dst, uint
void
rtref(struct rtentry *rt)
{
- rt->rt_refcnt++;
+ atomic_inc_int(&rt->rt_refcnt);
}
void
@@ -348,14 +350,16 @@ rtfree(struct rtentry *rt)
if (rt == NULL)
return;
- if (--rt->rt_refcnt <= 0) {
+ if (atomic_dec_int_nv(&rt->rt_refcnt) <= 0) {
KASSERT(!ISSET(rt->rt_flags, RTF_UP));
KASSERT(!RT_ROOT(rt));
- rttrash--;
+ atomic_dec_int(&rttrash);
if (rt->rt_refcnt < 0) {
printf("rtfree: %p not freed (neg refs)\n", rt);
return;
}
+
+ KERNEL_LOCK();
rt_timer_remove_all(rt);
ifa = rt->rt_ifa;
if (ifa)
@@ -368,6 +372,8 @@ rtfree(struct rtentry *rt)
if (rt->rt_gateway)
free(rt->rt_gateway, M_RTABLE, 0);
free(rt_key(rt), M_RTABLE, 0);
+ KERNEL_UNLOCK();
+
pool_put(&rtentry_pool, rt);
}
}
@@ -773,7 +779,7 @@ rtrequest1(int req, struct rt_addrinfo *
rt->rt_flags &= ~RTF_UP;
if ((ifa = rt->rt_ifa) && ifa->ifa_rtrequest)
ifa->ifa_rtrequest(RTM_DELETE, rt);
- rttrash++;
+ atomic_inc_int(&rttrash);
if (ret_nrt != NULL)
*ret_nrt = rt;
Index: sys/netmpls/mpls_input.c
===================================================================
RCS file: /cvs/src/sys/netmpls/mpls_input.c,v
retrieving revision 1.50
diff -u -p -r1.50 mpls_input.c
--- sys/netmpls/mpls_input.c 23 Sep 2015 08:49:46 -0000 1.50
+++ sys/netmpls/mpls_input.c 22 Oct 2015 17:21:52 -0000
@@ -170,9 +170,7 @@ do_v6:
}
}
- KERNEL_LOCK();
rt = rtalloc(smplstosa(smpls), RT_REPORT|RT_RESOLVE, 0);
- KERNEL_UNLOCK();
if (rt == NULL) {
/* no entry for this label */
#ifdef MPLS_DEBUG
@@ -290,9 +288,7 @@ do_v6:
if (ifp != NULL && rt_mpls->mpls_operation != MPLS_OP_LOCAL)
break;
- KERNEL_LOCK();
rtfree(rt);
- KERNEL_UNLOCK();
rt = NULL;
}
@@ -323,11 +319,7 @@ do_v6:
(*ifp->if_ll_output)(ifp, m, smplstosa(smpls), rt);
KERNEL_UNLOCK();
done:
- if (rt) {
- KERNEL_LOCK();
- rtfree(rt);
- KERNEL_UNLOCK();
- }
+ rtfree(rt);
}
int
@@ -394,7 +386,7 @@ mpls_do_error(struct mbuf *m, int type,
struct in_ifaddr *ia;
struct icmp *icp;
struct ip *ip;
- int nstk;
+ int nstk, error;
for (nstk = 0; nstk < MPLS_INKERNEL_LOOP_MAX; nstk++) {
if (m->m_len < sizeof(*shim) &&
@@ -427,9 +419,7 @@ mpls_do_error(struct mbuf *m, int type,
smpls->smpls_len = sizeof(*smpls);
smpls->smpls_label = shim->shim_label & MPLS_LABEL_MASK;
- KERNEL_LOCK();
rt = rtalloc(smplstosa(smpls), RT_REPORT|RT_RESOLVE, 0);
- KERNEL_UNLOCK();
if (rt == NULL) {
/* no entry for this label */
m_freem(m);
@@ -442,19 +432,16 @@ mpls_do_error(struct mbuf *m, int type,
* less interface we need to find some other IP to
* use as source.
*/
- KERNEL_LOCK();
rtfree(rt);
- KERNEL_UNLOCK();
m_freem(m);
return (NULL);
}
- KERNEL_LOCK();
rtfree(rt);
- if (icmp_reflect(m, NULL, ia)) {
- KERNEL_UNLOCK();
- return (NULL);
- }
+ KERNEL_LOCK();
+ error = icmp_reflect(m, NULL, ia);
KERNEL_UNLOCK();
+ if (error)
+ return (NULL);
ip = mtod(m, struct ip *);
/* stuff to fix up which is normaly done in ip_output */
