On 22/10/15(Thu) 19:42, Martin Pieuchot wrote:
> 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?
Updated diff after some comments from dlg@ and bluhm@.
Index: net/route.c
===================================================================
RCS file: /cvs/src/sys/net/route.c,v
retrieving revision 1.258
diff -u -p -r1.258 route.c
--- net/route.c 22 Oct 2015 17:19:38 -0000 1.258
+++ net/route.c 23 Oct 2015 12:38:58 -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);
}
@@ -337,25 +339,29 @@ rtalloc_mpath(struct sockaddr *dst, uint
void
rtref(struct rtentry *rt)
{
- rt->rt_refcnt++;
+ atomic_inc_int(&rt->rt_refcnt);
}
void
rtfree(struct rtentry *rt)
{
struct ifaddr *ifa;
+ int refcnt;
if (rt == NULL)
return;
- if (--rt->rt_refcnt <= 0) {
+ refcnt = (int)atomic_dec_int_nv(&rt->rt_refcnt);
+ if (refcnt <= 0) {
KASSERT(!ISSET(rt->rt_flags, RTF_UP));
KASSERT(!RT_ROOT(rt));
- rttrash--;
- if (rt->rt_refcnt < 0) {
+ atomic_dec_int(&rttrash);
+ if (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 +374,8 @@ 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 +781,7 @@ 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;
