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ipv6: Stop rt6_info from using inet_peer's metrics
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inet_peer is indexed by the dst address alone.  However, the fib6 tree
could have multiple routing entries (rt6_info) for the same dst. For
example,
1. A /128 dst via multiple gateways.
2. A RTF_CACHE route cloned from a /128 route.

In the above cases, all of them will share the same metrics and
step on each other.

This patch will steer away from inet_peer's metrics and use
dst_cow_metrics_generic() for everything.

Change Highlights:
1. Remove rt6_cow_metrics() which currently acquires metrics from
   inet_peer for DST_HOST route (i.e. /128 route).
2. Add rt6i_pmtu to take care of the pmtu update to avoid creating a
   full size metrics just to override the RTAX_MTU.
3. After (2), the RTF_CACHE route can also share the metrics with its
   dst.from route, by:
   dst_init_metrics(&cache_rt->dst, dst_metrics_ptr(cache_rt->dst.from), true);
4. Stop creating RTF_CACHE route by cloning another RTF_CACHE route.  Instead,
   directly clone from rt->dst.

   [ Currently, cloning from another RTF_CACHE is only possible during
     rt6_do_redirect().  Also, the old clone is removed from the tree
     immediately after the new clone is added. ]

   In case of cloning from an older redirect RTF_CACHE, it should work as
   before.

   In case of cloning from an older pmtu RTF_CACHE, this patch will forget
   the pmtu and re-learn it (if there is any) from the redirected route.

The _rt6i_peer and DST_METRICS_FORCE_OVERWRITE will be removed
in the next cleanup patch.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Reviewed-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Martin KaFai Lau authored and David S. Miller committed May 2, 2015
1 parent 653437d commit 4b32b5a
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Showing 2 changed files with 60 additions and 52 deletions.
10 changes: 1 addition & 9 deletions include/net/ip6_fib.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -124,6 +124,7 @@ struct rt6_info {
unsigned long _rt6i_peer;

u32 rt6i_metric;
u32 rt6i_pmtu;
/* more non-fragment space at head required */
unsigned short rt6i_nfheader_len;
u8 rt6i_protocol;
Expand Down Expand Up @@ -189,15 +190,6 @@ static inline void rt6_update_expires(struct rt6_info *rt0, int timeout)
rt0->rt6i_flags |= RTF_EXPIRES;
}

static inline void rt6_set_from(struct rt6_info *rt, struct rt6_info *from)
{
struct dst_entry *new = (struct dst_entry *) from;

rt->rt6i_flags &= ~RTF_EXPIRES;
dst_hold(new);
rt->dst.from = new;
}

static inline void ip6_rt_put(struct rt6_info *rt)
{
/* dst_release() accepts a NULL parameter.
Expand Down
102 changes: 59 additions & 43 deletions net/ipv6/route.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -92,6 +92,7 @@ static void ip6_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
struct sk_buff *skb, u32 mtu);
static void rt6_do_redirect(struct dst_entry *dst, struct sock *sk,
struct sk_buff *skb);
static void rt6_dst_from_metrics_check(struct rt6_info *rt);
static int rt6_score_route(struct rt6_info *rt, int oif, int strict);

#ifdef CONFIG_IPV6_ROUTE_INFO
Expand Down Expand Up @@ -136,33 +137,12 @@ static struct inet_peer *rt6_get_peer_create(struct rt6_info *rt)

static u32 *ipv6_cow_metrics(struct dst_entry *dst, unsigned long old)
{
struct rt6_info *rt = (struct rt6_info *) dst;
struct inet_peer *peer;
u32 *p = NULL;
struct rt6_info *rt = (struct rt6_info *)dst;

if (!(rt->dst.flags & DST_HOST))
if (rt->rt6i_flags & RTF_CACHE)
return NULL;
else
return dst_cow_metrics_generic(dst, old);

peer = rt6_get_peer_create(rt);
if (peer) {
u32 *old_p = __DST_METRICS_PTR(old);
unsigned long prev, new;

p = peer->metrics;
if (inet_metrics_new(peer) ||
(old & DST_METRICS_FORCE_OVERWRITE))
memcpy(p, old_p, sizeof(u32) * RTAX_MAX);

new = (unsigned long) p;
prev = cmpxchg(&dst->_metrics, old, new);

if (prev != old) {
p = __DST_METRICS_PTR(prev);
if (prev & DST_METRICS_READ_ONLY)
p = NULL;
}
}
return p;
}

static inline const void *choose_neigh_daddr(struct rt6_info *rt,
Expand Down Expand Up @@ -323,8 +303,7 @@ static void ip6_dst_destroy(struct dst_entry *dst)
struct inet6_dev *idev = rt->rt6i_idev;
struct dst_entry *from = dst->from;

if (!(rt->dst.flags & DST_HOST))
dst_destroy_metrics_generic(dst);
dst_destroy_metrics_generic(dst);

if (idev) {
rt->rt6i_idev = NULL;
Expand All @@ -333,11 +312,6 @@ static void ip6_dst_destroy(struct dst_entry *dst)

dst->from = NULL;
dst_release(from);

if (rt6_has_peer(rt)) {
struct inet_peer *peer = rt6_peer_ptr(rt);
inet_putpeer(peer);
}
}

static void ip6_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
Expand Down Expand Up @@ -1003,6 +977,7 @@ static struct rt6_info *ip6_pol_route(struct net *net, struct fib6_table *table,
goto redo_fib6_lookup_lock;

out2:
rt6_dst_from_metrics_check(rt);
rt->dst.lastuse = jiffies;
rt->dst.__use++;

Expand Down Expand Up @@ -1111,6 +1086,13 @@ struct dst_entry *ip6_blackhole_route(struct net *net, struct dst_entry *dst_ori
* Destination cache support functions
*/

static void rt6_dst_from_metrics_check(struct rt6_info *rt)
{
if (rt->dst.from &&
dst_metrics_ptr(&rt->dst) != dst_metrics_ptr(rt->dst.from))
dst_init_metrics(&rt->dst, dst_metrics_ptr(rt->dst.from), true);
}

static struct dst_entry *ip6_dst_check(struct dst_entry *dst, u32 cookie)
{
struct rt6_info *rt;
Expand All @@ -1127,6 +1109,8 @@ static struct dst_entry *ip6_dst_check(struct dst_entry *dst, u32 cookie)
if (rt6_check_expired(rt))
return NULL;

rt6_dst_from_metrics_check(rt);

return dst;
}

Expand Down Expand Up @@ -1179,7 +1163,7 @@ static void ip6_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
if (mtu < IPV6_MIN_MTU)
mtu = IPV6_MIN_MTU;

dst_metric_set(dst, RTAX_MTU, mtu);
rt6->rt6i_pmtu = mtu;
rt6_update_expires(rt6, net->ipv6.sysctl.ip6_rt_mtu_expires);
}
}
Expand Down Expand Up @@ -1359,9 +1343,14 @@ static unsigned int ip6_default_advmss(const struct dst_entry *dst)

static unsigned int ip6_mtu(const struct dst_entry *dst)
{
const struct rt6_info *rt = (const struct rt6_info *)dst;
unsigned int mtu = rt->rt6i_pmtu;
struct inet6_dev *idev;
unsigned int mtu = dst_metric_raw(dst, RTAX_MTU);

if (mtu)
goto out;

mtu = dst_metric_raw(dst, RTAX_MTU);
if (mtu)
goto out;

Expand Down Expand Up @@ -1947,12 +1936,27 @@ static void rt6_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_bu
* Misc support functions
*/

static void rt6_set_from(struct rt6_info *rt, struct rt6_info *from)
{
BUG_ON(from->dst.from);

rt->rt6i_flags &= ~RTF_EXPIRES;
dst_hold(&from->dst);
rt->dst.from = &from->dst;
dst_init_metrics(&rt->dst, dst_metrics_ptr(&from->dst), true);
}

static struct rt6_info *ip6_rt_copy(struct rt6_info *ort,
const struct in6_addr *dest)
{
struct net *net = dev_net(ort->dst.dev);
struct rt6_info *rt = ip6_dst_alloc(net, ort->dst.dev, 0,
ort->rt6i_table);
struct rt6_info *rt;

if (ort->rt6i_flags & RTF_CACHE)
ort = (struct rt6_info *)ort->dst.from;

rt = ip6_dst_alloc(net, ort->dst.dev, 0,
ort->rt6i_table);

if (rt) {
rt->dst.input = ort->dst.input;
Expand All @@ -1961,7 +1965,6 @@ static struct rt6_info *ip6_rt_copy(struct rt6_info *ort,

rt->rt6i_dst.addr = *dest;
rt->rt6i_dst.plen = 128;
dst_copy_metrics(&rt->dst, &ort->dst);
rt->dst.error = ort->dst.error;
rt->rt6i_idev = ort->rt6i_idev;
if (rt->rt6i_idev)
Expand Down Expand Up @@ -2393,11 +2396,20 @@ static int rt6_mtu_change_route(struct rt6_info *rt, void *p_arg)
PMTU discouvery.
*/
if (rt->dst.dev == arg->dev &&
!dst_metric_locked(&rt->dst, RTAX_MTU) &&
(dst_mtu(&rt->dst) >= arg->mtu ||
(dst_mtu(&rt->dst) < arg->mtu &&
dst_mtu(&rt->dst) == idev->cnf.mtu6))) {
dst_metric_set(&rt->dst, RTAX_MTU, arg->mtu);
!dst_metric_locked(&rt->dst, RTAX_MTU)) {
if (rt->rt6i_flags & RTF_CACHE) {
/* For RTF_CACHE with rt6i_pmtu == 0
* (i.e. a redirected route),
* the metrics of its rt->dst.from has already
* been updated.
*/
if (rt->rt6i_pmtu && rt->rt6i_pmtu > arg->mtu)
rt->rt6i_pmtu = arg->mtu;
} else if (dst_mtu(&rt->dst) >= arg->mtu ||
(dst_mtu(&rt->dst) < arg->mtu &&
dst_mtu(&rt->dst) == idev->cnf.mtu6)) {
dst_metric_set(&rt->dst, RTAX_MTU, arg->mtu);
}
}
return 0;
}
Expand Down Expand Up @@ -2627,6 +2639,7 @@ static int rt6_fill_node(struct net *net,
int iif, int type, u32 portid, u32 seq,
int prefix, int nowait, unsigned int flags)
{
u32 metrics[RTAX_MAX];
struct rtmsg *rtm;
struct nlmsghdr *nlh;
long expires;
Expand Down Expand Up @@ -2740,7 +2753,10 @@ static int rt6_fill_node(struct net *net,
goto nla_put_failure;
}

if (rtnetlink_put_metrics(skb, dst_metrics_ptr(&rt->dst)) < 0)
memcpy(metrics, dst_metrics_ptr(&rt->dst), sizeof(metrics));
if (rt->rt6i_pmtu)
metrics[RTAX_MTU - 1] = rt->rt6i_pmtu;
if (rtnetlink_put_metrics(skb, metrics) < 0)
goto nla_put_failure;

if (rt->rt6i_flags & RTF_GATEWAY) {
Expand Down

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