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Message-Id: <20120719.143517.1962854632305184667.davem@davemloft.net>
Date: Thu, 19 Jul 2012 14:35:17 -0700 (PDT)
From: David Miller <davem@...emloft.net>
To: netdev@...r.kernel.org
Subject: [PATCH 08/16] net: Document dst->obsolete better.
Add a big comment explaining how the field works, and use defines
instead of magic constants for the values assigned to it.
Suggested by Joe Perches.
Signed-off-by: David S. Miller <davem@...emloft.net>
---
include/net/dst.h | 14 +++++++++++++-
net/core/dst.c | 4 ++--
net/decnet/dn_route.c | 4 ++--
net/ipv4/route.c | 5 +++--
net/ipv6/route.c | 4 ++--
net/sctp/transport.c | 2 +-
net/xfrm/xfrm_policy.c | 23 ++++++++++++-----------
7 files changed, 35 insertions(+), 21 deletions(-)
diff --git a/include/net/dst.h b/include/net/dst.h
index 5161046..0df661a 100644
--- a/include/net/dst.h
+++ b/include/net/dst.h
@@ -65,7 +65,19 @@ struct dst_entry {
unsigned short pending_confirm;
short error;
+
+ /* A non-zero value of dst->obsolete forces by-hand validation
+ * of the route entry. Positive values are set by the generic
+ * dst layer to indicate that the entry has been forcefully
+ * destroyed.
+ *
+ * Negative values are used by the implementation layer code to
+ * force invocation of the dst_ops->check() method.
+ */
short obsolete;
+#define DST_OBSOLETE_NONE 0
+#define DST_OBSOLETE_DEAD 2
+#define DST_OBSOLETE_FORCE_CHK -1
unsigned short header_len; /* more space at head required */
unsigned short trailer_len; /* space to reserve at tail */
#ifdef CONFIG_IP_ROUTE_CLASSID
@@ -359,7 +371,7 @@ extern struct dst_entry *dst_destroy(struct dst_entry *dst);
static inline void dst_free(struct dst_entry *dst)
{
- if (dst->obsolete > 1)
+ if (dst->obsolete > 0)
return;
if (!atomic_read(&dst->__refcnt)) {
dst = dst_destroy(dst);
diff --git a/net/core/dst.c b/net/core/dst.c
index 07bacff..069d51d 100644
--- a/net/core/dst.c
+++ b/net/core/dst.c
@@ -94,7 +94,7 @@ loop:
* But we do not have state "obsoleted, but
* referenced by parent", so it is right.
*/
- if (dst->obsolete > 1)
+ if (dst->obsolete > 0)
continue;
___dst_free(dst);
@@ -202,7 +202,7 @@ static void ___dst_free(struct dst_entry *dst)
*/
if (dst->dev == NULL || !(dst->dev->flags&IFF_UP))
dst->input = dst->output = dst_discard;
- dst->obsolete = 2;
+ dst->obsolete = DST_OBSOLETE_DEAD;
}
void __dst_free(struct dst_entry *dst)
diff --git a/net/decnet/dn_route.c b/net/decnet/dn_route.c
index 47de90d..23cc11d 100644
--- a/net/decnet/dn_route.c
+++ b/net/decnet/dn_route.c
@@ -1176,7 +1176,7 @@ make_route:
if (dev_out->flags & IFF_LOOPBACK)
flags |= RTCF_LOCAL;
- rt = dst_alloc(&dn_dst_ops, dev_out, 1, 0, DST_HOST);
+ rt = dst_alloc(&dn_dst_ops, dev_out, 1, DST_OBSOLETE_NONE, DST_HOST);
if (rt == NULL)
goto e_nobufs;
@@ -1444,7 +1444,7 @@ static int dn_route_input_slow(struct sk_buff *skb)
}
make_route:
- rt = dst_alloc(&dn_dst_ops, out_dev, 0, 0, DST_HOST);
+ rt = dst_alloc(&dn_dst_ops, out_dev, 0, DST_OBSOLETE_NONE, DST_HOST);
if (rt == NULL)
goto e_nobufs;
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 4e9e734..23078d6 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1221,7 +1221,7 @@ static void rt_set_nexthop(struct rtable *rt, const struct flowi4 *fl4,
static struct rtable *rt_dst_alloc(struct net_device *dev,
bool nopolicy, bool noxfrm)
{
- return dst_alloc(&ipv4_dst_ops, dev, 1, -1,
+ return dst_alloc(&ipv4_dst_ops, dev, 1, DST_OBSOLETE_FORCE_CHK,
DST_HOST | DST_NOCACHE |
(nopolicy ? DST_NOPOLICY : 0) |
(noxfrm ? DST_NOXFRM : 0));
@@ -1969,9 +1969,10 @@ static struct dst_ops ipv4_dst_blackhole_ops = {
struct dst_entry *ipv4_blackhole_route(struct net *net, struct dst_entry *dst_orig)
{
- struct rtable *rt = dst_alloc(&ipv4_dst_blackhole_ops, NULL, 1, 0, 0);
struct rtable *ort = (struct rtable *) dst_orig;
+ struct rtable *rt;
+ rt = dst_alloc(&ipv4_dst_blackhole_ops, NULL, 1, DST_OBSOLETE_NONE, 0);
if (rt) {
struct dst_entry *new = &rt->dst;
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 84f6564..cf02cb9 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -281,7 +281,7 @@ static inline struct rt6_info *ip6_dst_alloc(struct net *net,
struct fib6_table *table)
{
struct rt6_info *rt = dst_alloc(&net->ipv6.ip6_dst_ops, dev,
- 0, 0, flags);
+ 0, DST_OBSOLETE_NONE, flags);
if (rt) {
struct dst_entry *dst = &rt->dst;
@@ -985,7 +985,7 @@ struct dst_entry *ip6_blackhole_route(struct net *net, struct dst_entry *dst_ori
struct rt6_info *rt, *ort = (struct rt6_info *) dst_orig;
struct dst_entry *new = NULL;
- rt = dst_alloc(&ip6_dst_blackhole_ops, ort->dst.dev, 1, 0, 0);
+ rt = dst_alloc(&ip6_dst_blackhole_ops, ort->dst.dev, 1, DST_OBSOLETE_NONE, 0);
if (rt) {
new = &rt->dst;
diff --git a/net/sctp/transport.c b/net/sctp/transport.c
index a6b7ee9..ec3a12b 100644
--- a/net/sctp/transport.c
+++ b/net/sctp/transport.c
@@ -216,7 +216,7 @@ void sctp_transport_set_owner(struct sctp_transport *transport,
void sctp_transport_pmtu(struct sctp_transport *transport, struct sock *sk)
{
/* If we don't have a fresh route, look one up */
- if (!transport->dst || transport->dst->obsolete > 1) {
+ if (!transport->dst || transport->dst->obsolete) {
dst_release(transport->dst);
transport->af_specific->get_dst(transport, &transport->saddr,
&transport->fl, sk);
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 65bd1ca5..c5a5165 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -1350,7 +1350,7 @@ static inline struct xfrm_dst *xfrm_alloc_dst(struct net *net, int family)
default:
BUG();
}
- xdst = dst_alloc(dst_ops, NULL, 0, 0, 0);
+ xdst = dst_alloc(dst_ops, NULL, 0, DST_OBSOLETE_NONE, 0);
if (likely(xdst)) {
struct dst_entry *dst = &xdst->u.dst;
@@ -1477,7 +1477,7 @@ static struct dst_entry *xfrm_bundle_create(struct xfrm_policy *policy,
dst1->xfrm = xfrm[i];
xdst->xfrm_genid = xfrm[i]->genid;
- dst1->obsolete = -1;
+ dst1->obsolete = DST_OBSOLETE_FORCE_CHK;
dst1->flags |= DST_HOST;
dst1->lastuse = now;
@@ -2219,12 +2219,13 @@ EXPORT_SYMBOL(__xfrm_route_forward);
static struct dst_entry *xfrm_dst_check(struct dst_entry *dst, u32 cookie)
{
/* Code (such as __xfrm4_bundle_create()) sets dst->obsolete
- * to "-1" to force all XFRM destinations to get validated by
- * dst_ops->check on every use. We do this because when a
- * normal route referenced by an XFRM dst is obsoleted we do
- * not go looking around for all parent referencing XFRM dsts
- * so that we can invalidate them. It is just too much work.
- * Instead we make the checks here on every use. For example:
+ * to DST_OBSOLETE_FORCE_CHK to force all XFRM destinations to
+ * get validated by dst_ops->check on every use. We do this
+ * because when a normal route referenced by an XFRM dst is
+ * obsoleted we do not go looking around for all parent
+ * referencing XFRM dsts so that we can invalidate them. It
+ * is just too much work. Instead we make the checks here on
+ * every use. For example:
*
* XFRM dst A --> IPv4 dst X
*
@@ -2234,9 +2235,9 @@ static struct dst_entry *xfrm_dst_check(struct dst_entry *dst, u32 cookie)
* stale_bundle() check.
*
* When a policy's bundle is pruned, we dst_free() the XFRM
- * dst which causes it's ->obsolete field to be set to a
- * positive non-zero integer. If an XFRM dst has been pruned
- * like this, we want to force a new route lookup.
+ * dst which causes it's ->obsolete field to be set to
+ * DST_OBSOLETE_DEAD. If an XFRM dst has been pruned like
+ * this, we want to force a new route lookup.
*/
if (dst->obsolete < 0 && !stale_bundle(dst))
return dst;
--
1.7.10.4
--
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