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net: pmtu_expires fixes

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commit 2c8cec5c10 (ipv4: Cache learned PMTU information in inetpeer)
added some racy peer->pmtu_expires accesses.

As its value can be changed by another cpu/thread, we should be more
careful, reading its value once.

Add peer_pmtu_expired() and peer_pmtu_cleaned() helpers

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2011-06-08 06:07:07 +00:00 committed by David S. Miller
parent 6c43e0465f
commit fe6fe792fa
1 changed files with 44 additions and 34 deletions
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78
net/ipv4/route.c
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@ -1316,6 +1316,23 @@ void ip_rt_redirect(__be32 old_gw, __be32 daddr, __be32 new_gw,
;
}
static bool peer_pmtu_expired(struct inet_peer *peer)
{
unsigned long orig = ACCESS_ONCE(peer->pmtu_expires);
return orig &&
time_after_eq(jiffies, orig) &&
cmpxchg(&peer->pmtu_expires, orig, 0) == orig;
}
static bool peer_pmtu_cleaned(struct inet_peer *peer)
{
unsigned long orig = ACCESS_ONCE(peer->pmtu_expires);
return orig &&
cmpxchg(&peer->pmtu_expires, orig, 0) == orig;
}
static struct dst_entry *ipv4_negative_advice(struct dst_entry *dst)
{
struct rtable *rt = (struct rtable *)dst;
@ -1331,14 +1348,8 @@ static struct dst_entry *ipv4_negative_advice(struct dst_entry *dst)
rt_genid(dev_net(dst->dev)));
rt_del(hash, rt);
ret = NULL;
} else if (rt->peer &&
rt->peer->pmtu_expires &&
time_after_eq(jiffies, rt->peer->pmtu_expires)) {
unsigned long orig = rt->peer->pmtu_expires;
if (cmpxchg(&rt->peer->pmtu_expires, orig, 0) == orig)
dst_metric_set(dst, RTAX_MTU,
rt->peer->pmtu_orig);
} else if (rt->peer && peer_pmtu_expired(rt->peer)) {
dst_metric_set(dst, RTAX_MTU, rt->peer->pmtu_orig);
}
}
return ret;
@ -1531,8 +1542,10 @@ unsigned short ip_rt_frag_needed(struct net *net, const struct iphdr *iph,
static void check_peer_pmtu(struct dst_entry *dst, struct inet_peer *peer)
{
unsigned long expires = peer->pmtu_expires;
unsigned long expires = ACCESS_ONCE(peer->pmtu_expires);
if (!expires)
return;
if (time_before(jiffies, expires)) {
u32 orig_dst_mtu = dst_mtu(dst);
if (peer->pmtu_learned < orig_dst_mtu) {
@ -1555,10 +1568,11 @@ static void ip_rt_update_pmtu(struct dst_entry *dst, u32 mtu)
rt_bind_peer(rt, rt->rt_dst, 1);
peer = rt->peer;
if (peer) {
unsigned long pmtu_expires = ACCESS_ONCE(peer->pmtu_expires);
if (mtu < ip_rt_min_pmtu)
mtu = ip_rt_min_pmtu;
if (!peer->pmtu_expires || mtu < peer->pmtu_learned) {
unsigned long pmtu_expires;
if (!pmtu_expires || mtu < peer->pmtu_learned) {
pmtu_expires = jiffies + ip_rt_mtu_expires;
if (!pmtu_expires)
@ -1612,13 +1626,14 @@ static struct dst_entry *ipv4_dst_check(struct dst_entry *dst, u32 cookie)
rt_bind_peer(rt, rt->rt_dst, 0);
peer = rt->peer;
if (peer && peer->pmtu_expires)
if (peer) {
check_peer_pmtu(dst, peer);
if (peer && peer->redirect_learned.a4 &&
peer->redirect_learned.a4 != rt->rt_gateway) {
if (check_peer_redir(dst, peer))
return NULL;
if (peer->redirect_learned.a4 &&
peer->redirect_learned.a4 != rt->rt_gateway) {
if (check_peer_redir(dst, peer))
return NULL;
}
}
rt->rt_peer_genid = rt_peer_genid();
@ -1649,14 +1664,8 @@ static void ipv4_link_failure(struct sk_buff *skb)
icmp_send(skb, ICMP_DEST_UNREACH, ICMP_HOST_UNREACH, 0);
rt = skb_rtable(skb);
if (rt &&
rt->peer &&
rt->peer->pmtu_expires) {
unsigned long orig = rt->peer->pmtu_expires;
if (cmpxchg(&rt->peer->pmtu_expires, orig, 0) == orig)
dst_metric_set(&rt->dst, RTAX_MTU, rt->peer->pmtu_orig);
}
if (rt && rt->peer && peer_pmtu_cleaned(rt->peer))
dst_metric_set(&rt->dst, RTAX_MTU, rt->peer->pmtu_orig);
}
static int ip_rt_bug(struct sk_buff *skb)
@ -1770,8 +1779,7 @@ static void rt_init_metrics(struct rtable *rt, const struct flowi4 *fl4,
sizeof(u32) * RTAX_MAX);
dst_init_metrics(&rt->dst, peer->metrics, false);
if (peer->pmtu_expires)
check_peer_pmtu(&rt->dst, peer);
check_peer_pmtu(&rt->dst, peer);
if (peer->redirect_learned.a4 &&
peer->redirect_learned.a4 != rt->rt_gateway) {
rt->rt_gateway = peer->redirect_learned.a4;
@ -2775,7 +2783,8 @@ static int rt_fill_info(struct net *net,
struct rtable *rt = skb_rtable(skb);
struct rtmsg *r;
struct nlmsghdr *nlh;
long expires;
long expires = 0;
const struct inet_peer *peer = rt->peer;
u32 id = 0, ts = 0, tsage = 0, error;
nlh = nlmsg_put(skb, pid, seq, event, sizeof(*r), flags);
@ -2823,15 +2832,16 @@ static int rt_fill_info(struct net *net,
NLA_PUT_BE32(skb, RTA_MARK, rt->rt_mark);
error = rt->dst.error;
expires = (rt->peer && rt->peer->pmtu_expires) ?
rt->peer->pmtu_expires - jiffies : 0;
if (rt->peer) {
if (peer) {
inet_peer_refcheck(rt->peer);
id = atomic_read(&rt->peer->ip_id_count) & 0xffff;
if (rt->peer->tcp_ts_stamp) {
ts = rt->peer->tcp_ts;
tsage = get_seconds() - rt->peer->tcp_ts_stamp;
id = atomic_read(&peer->ip_id_count) & 0xffff;
if (peer->tcp_ts_stamp) {
ts = peer->tcp_ts;
tsage = get_seconds() - peer->tcp_ts_stamp;
}
expires = ACCESS_ONCE(peer->pmtu_expires);
if (expires)
expires -= jiffies;
}
if (rt_is_input_route(rt)) {