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net/ipv6: Remove expired routes with a separated list of routes.
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FIB6 GC walks trees of fib6_tables to remove expired routes. Walking a tree
can be expensive if the number of routes in a table is big, even if most of
them are permanent. Checking routes in a separated list of routes having
expiration will avoid this potential issue.

Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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@ThinkerYzu1 @davem330
ThinkerYzu1 authored and davem330 committed Feb 12, 2024
1 parent 60df43d commit 5eb902b
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Showing 5 changed files with 154 additions and 16 deletions.
46 changes: 45 additions & 1 deletion include/net/ip6_fib.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -173,6 +173,9 @@ struct fib6_info {

refcount_t fib6_ref;
unsigned long expires;

struct hlist_node gc_link;

struct dst_metrics *fib6_metrics;
#define fib6_pmtu fib6_metrics->metrics[RTAX_MTU-1]

Expand Down Expand Up @@ -241,12 +244,18 @@ static inline bool fib6_requires_src(const struct fib6_info *rt)
return rt->fib6_src.plen > 0;
}

/* The callers should hold f6i->fib6_table->tb6_lock if a route has ever
* been added to a table before.
*/
static inline void fib6_clean_expires(struct fib6_info *f6i)
{
f6i->fib6_flags &= ~RTF_EXPIRES;
f6i->expires = 0;
}

/* The callers should hold f6i->fib6_table->tb6_lock if a route has ever
* been added to a table before.
*/
static inline void fib6_set_expires(struct fib6_info *f6i,
unsigned long expires)
{
Expand Down Expand Up @@ -327,8 +336,10 @@ static inline bool fib6_info_hold_safe(struct fib6_info *f6i)

static inline void fib6_info_release(struct fib6_info *f6i)
{
if (f6i && refcount_dec_and_test(&f6i->fib6_ref))
if (f6i && refcount_dec_and_test(&f6i->fib6_ref)) {
DEBUG_NET_WARN_ON_ONCE(!hlist_unhashed(&f6i->gc_link));
call_rcu(&f6i->rcu, fib6_info_destroy_rcu);
}
}

enum fib6_walk_state {
Expand Down Expand Up @@ -382,6 +393,7 @@ struct fib6_table {
struct inet_peer_base tb6_peers;
unsigned int flags;
unsigned int fib_seq;
struct hlist_head tb6_gc_hlist; /* GC candidates */
#define RT6_TABLE_HAS_DFLT_ROUTER BIT(0)
};

Expand Down Expand Up @@ -498,6 +510,38 @@ void fib6_gc_cleanup(void);

int fib6_init(void);

/* Add the route to the gc list if it is not already there
*
* The callers should hold f6i->fib6_table->tb6_lock.
*/
static inline void fib6_add_gc_list(struct fib6_info *f6i)
{
/* If fib6_node is null, the f6i is not in (or removed from) the
* table.
*
* There is a gap between finding the f6i from the table and
* calling this function without the protection of the tb6_lock.
* This check makes sure the f6i is not added to the gc list when
* it is not on the table.
*/
if (!rcu_dereference_protected(f6i->fib6_node,
lockdep_is_held(&f6i->fib6_table->tb6_lock)))
return;

if (hlist_unhashed(&f6i->gc_link))
hlist_add_head(&f6i->gc_link, &f6i->fib6_table->tb6_gc_hlist);
}

/* Remove the route from the gc list if it is on the list.
*
* The callers should hold f6i->fib6_table->tb6_lock.
*/
static inline void fib6_remove_gc_list(struct fib6_info *f6i)
{
if (!hlist_unhashed(&f6i->gc_link))
hlist_del_init(&f6i->gc_link);
}

struct ipv6_route_iter {
struct seq_net_private p;
struct fib6_walker w;
Expand Down
41 changes: 34 additions & 7 deletions net/ipv6/addrconf.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1255,6 +1255,7 @@ static void
cleanup_prefix_route(struct inet6_ifaddr *ifp, unsigned long expires,
bool del_rt, bool del_peer)
{
struct fib6_table *table;
struct fib6_info *f6i;

f6i = addrconf_get_prefix_route(del_peer ? &ifp->peer_addr : &ifp->addr,
Expand All @@ -1264,8 +1265,15 @@ cleanup_prefix_route(struct inet6_ifaddr *ifp, unsigned long expires,
if (del_rt)
ip6_del_rt(dev_net(ifp->idev->dev), f6i, false);
else {
if (!(f6i->fib6_flags & RTF_EXPIRES))
if (!(f6i->fib6_flags & RTF_EXPIRES)) {
table = f6i->fib6_table;
spin_lock_bh(&table->tb6_lock);

fib6_set_expires(f6i, expires);
fib6_add_gc_list(f6i);

spin_unlock_bh(&table->tb6_lock);
}
fib6_info_release(f6i);
}
}
Expand Down Expand Up @@ -2706,6 +2714,7 @@ EXPORT_SYMBOL_GPL(addrconf_prefix_rcv_add_addr);
void addrconf_prefix_rcv(struct net_device *dev, u8 *opt, int len, bool sllao)
{
struct prefix_info *pinfo;
struct fib6_table *table;
__u32 valid_lft;
__u32 prefered_lft;
int addr_type, err;
Expand Down Expand Up @@ -2782,11 +2791,20 @@ void addrconf_prefix_rcv(struct net_device *dev, u8 *opt, int len, bool sllao)
if (valid_lft == 0) {
ip6_del_rt(net, rt, false);
rt = NULL;
} else if (addrconf_finite_timeout(rt_expires)) {
/* not infinity */
fib6_set_expires(rt, jiffies + rt_expires);
} else {
fib6_clean_expires(rt);
table = rt->fib6_table;
spin_lock_bh(&table->tb6_lock);

if (addrconf_finite_timeout(rt_expires)) {
/* not infinity */
fib6_set_expires(rt, jiffies + rt_expires);
fib6_add_gc_list(rt);
} else {
fib6_clean_expires(rt);
fib6_remove_gc_list(rt);
}

spin_unlock_bh(&table->tb6_lock);
}
} else if (valid_lft) {
clock_t expires = 0;
Expand Down Expand Up @@ -4741,6 +4759,7 @@ static int modify_prefix_route(struct inet6_ifaddr *ifp,
unsigned long expires, u32 flags,
bool modify_peer)
{
struct fib6_table *table;
struct fib6_info *f6i;
u32 prio;

Expand All @@ -4761,10 +4780,18 @@ static int modify_prefix_route(struct inet6_ifaddr *ifp,
ifp->rt_priority, ifp->idev->dev,
expires, flags, GFP_KERNEL);
} else {
if (!expires)
table = f6i->fib6_table;
spin_lock_bh(&table->tb6_lock);

if (!expires) {
fib6_clean_expires(f6i);
else
fib6_remove_gc_list(f6i);
} else {
fib6_set_expires(f6i, expires);
fib6_add_gc_list(f6i);
}

spin_unlock_bh(&table->tb6_lock);

fib6_info_release(f6i);
}
Expand Down
60 changes: 55 additions & 5 deletions net/ipv6/ip6_fib.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -160,6 +160,8 @@ struct fib6_info *fib6_info_alloc(gfp_t gfp_flags, bool with_fib6_nh)
INIT_LIST_HEAD(&f6i->fib6_siblings);
refcount_set(&f6i->fib6_ref, 1);

INIT_HLIST_NODE(&f6i->gc_link);

return f6i;
}

Expand Down Expand Up @@ -246,6 +248,7 @@ static struct fib6_table *fib6_alloc_table(struct net *net, u32 id)
net->ipv6.fib6_null_entry);
table->tb6_root.fn_flags = RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;
inet_peer_base_init(&table->tb6_peers);
INIT_HLIST_HEAD(&table->tb6_gc_hlist);
}

return table;
Expand Down Expand Up @@ -1055,6 +1058,9 @@ static void fib6_purge_rt(struct fib6_info *rt, struct fib6_node *fn,
lockdep_is_held(&table->tb6_lock));
}
}

fib6_clean_expires(rt);
fib6_remove_gc_list(rt);
}

/*
Expand Down Expand Up @@ -1115,10 +1121,13 @@ static int fib6_add_rt2node(struct fib6_node *fn, struct fib6_info *rt,
rt->fib6_nsiblings = 0;
if (!(iter->fib6_flags & RTF_EXPIRES))
return -EEXIST;
if (!(rt->fib6_flags & RTF_EXPIRES))
if (!(rt->fib6_flags & RTF_EXPIRES)) {
fib6_clean_expires(iter);
else
fib6_remove_gc_list(iter);
} else {
fib6_set_expires(iter, rt->expires);
fib6_add_gc_list(iter);
}

if (rt->fib6_pmtu)
fib6_metric_set(iter, RTAX_MTU,
Expand Down Expand Up @@ -1477,6 +1486,10 @@ int fib6_add(struct fib6_node *root, struct fib6_info *rt,
if (rt->nh)
list_add(&rt->nh_list, &rt->nh->f6i_list);
__fib6_update_sernum_upto_root(rt, fib6_new_sernum(info->nl_net));

if (rt->fib6_flags & RTF_EXPIRES)
fib6_add_gc_list(rt);

fib6_start_gc(info->nl_net, rt);
}

Expand Down Expand Up @@ -2280,9 +2293,8 @@ static void fib6_flush_trees(struct net *net)
* Garbage collection
*/

static int fib6_age(struct fib6_info *rt, void *arg)
static int fib6_age(struct fib6_info *rt, struct fib6_gc_args *gc_args)
{
struct fib6_gc_args *gc_args = arg;
unsigned long now = jiffies;

/*
Expand All @@ -2307,6 +2319,42 @@ static int fib6_age(struct fib6_info *rt, void *arg)
return 0;
}

static void fib6_gc_table(struct net *net,
struct fib6_table *tb6,
struct fib6_gc_args *gc_args)
{
struct fib6_info *rt;
struct hlist_node *n;
struct nl_info info = {
.nl_net = net,
.skip_notify = false,
};

hlist_for_each_entry_safe(rt, n, &tb6->tb6_gc_hlist, gc_link)
if (fib6_age(rt, gc_args) == -1)
fib6_del(rt, &info);
}

static void fib6_gc_all(struct net *net, struct fib6_gc_args *gc_args)
{
struct fib6_table *table;
struct hlist_head *head;
unsigned int h;

rcu_read_lock();
for (h = 0; h < FIB6_TABLE_HASHSZ; h++) {
head = &net->ipv6.fib_table_hash[h];
hlist_for_each_entry_rcu(table, head, tb6_hlist) {
spin_lock_bh(&table->tb6_lock);

fib6_gc_table(net, table, gc_args);

spin_unlock_bh(&table->tb6_lock);
}
}
rcu_read_unlock();
}

void fib6_run_gc(unsigned long expires, struct net *net, bool force)
{
struct fib6_gc_args gc_args;
Expand All @@ -2322,7 +2370,7 @@ void fib6_run_gc(unsigned long expires, struct net *net, bool force)
net->ipv6.sysctl.ip6_rt_gc_interval;
gc_args.more = 0;

fib6_clean_all(net, fib6_age, &gc_args);
fib6_gc_all(net, &gc_args);
now = jiffies;
net->ipv6.ip6_rt_last_gc = now;

Expand Down Expand Up @@ -2382,6 +2430,7 @@ static int __net_init fib6_net_init(struct net *net)
net->ipv6.fib6_main_tbl->tb6_root.fn_flags =
RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;
inet_peer_base_init(&net->ipv6.fib6_main_tbl->tb6_peers);
INIT_HLIST_HEAD(&net->ipv6.fib6_main_tbl->tb6_gc_hlist);

#ifdef CONFIG_IPV6_MULTIPLE_TABLES
net->ipv6.fib6_local_tbl = kzalloc(sizeof(*net->ipv6.fib6_local_tbl),
Expand All @@ -2394,6 +2443,7 @@ static int __net_init fib6_net_init(struct net *net)
net->ipv6.fib6_local_tbl->tb6_root.fn_flags =
RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;
inet_peer_base_init(&net->ipv6.fib6_local_tbl->tb6_peers);
INIT_HLIST_HEAD(&net->ipv6.fib6_local_tbl->tb6_gc_hlist);
#endif
fib6_tables_init(net);

Expand Down
10 changes: 9 additions & 1 deletion net/ipv6/ndisc.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1237,6 +1237,7 @@ static enum skb_drop_reason ndisc_router_discovery(struct sk_buff *skb)
struct ndisc_options ndopts;
struct fib6_info *rt = NULL;
struct inet6_dev *in6_dev;
struct fib6_table *table;
u32 defrtr_usr_metric;
unsigned int pref = 0;
__u32 old_if_flags;
Expand Down Expand Up @@ -1410,8 +1411,15 @@ static enum skb_drop_reason ndisc_router_discovery(struct sk_buff *skb)
inet6_rt_notify(RTM_NEWROUTE, rt, &nlinfo, NLM_F_REPLACE);
}

if (rt)
if (rt) {
table = rt->fib6_table;
spin_lock_bh(&table->tb6_lock);

fib6_set_expires(rt, jiffies + (HZ * lifetime));
fib6_add_gc_list(rt);

spin_unlock_bh(&table->tb6_lock);
}
if (in6_dev->cnf.accept_ra_min_hop_limit < 256 &&
ra_msg->icmph.icmp6_hop_limit) {
if (in6_dev->cnf.accept_ra_min_hop_limit <= ra_msg->icmph.icmp6_hop_limit) {
Expand Down
13 changes: 11 additions & 2 deletions net/ipv6/route.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -931,6 +931,7 @@ int rt6_route_rcv(struct net_device *dev, u8 *opt, int len,
struct net *net = dev_net(dev);
struct route_info *rinfo = (struct route_info *) opt;
struct in6_addr prefix_buf, *prefix;
struct fib6_table *table;
unsigned int pref;
unsigned long lifetime;
struct fib6_info *rt;
Expand Down Expand Up @@ -989,10 +990,18 @@ int rt6_route_rcv(struct net_device *dev, u8 *opt, int len,
(rt->fib6_flags & ~RTF_PREF_MASK) | RTF_PREF(pref);

if (rt) {
if (!addrconf_finite_timeout(lifetime))
table = rt->fib6_table;
spin_lock_bh(&table->tb6_lock);

if (!addrconf_finite_timeout(lifetime)) {
fib6_clean_expires(rt);
else
fib6_remove_gc_list(rt);
} else {
fib6_set_expires(rt, jiffies + HZ * lifetime);
fib6_add_gc_list(rt);
}

spin_unlock_bh(&table->tb6_lock);

fib6_info_release(rt);
}
Expand Down

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