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Date: Mon, 26 Feb 2018 14:29:51 -0800
From: Wei Wang <weiwan@...gle.com>
To: David Ahern <dsahern@...il.com>
Cc: Linux Kernel Network Developers <netdev@...r.kernel.org>,
"David S . Miller" <davem@...emloft.net>,
Ido Schimmel <idosch@...sch.org>, roopa@...ulusnetworks.com,
Eric Dumazet <eric.dumazet@...il.com>,
Martin KaFai Lau <kafai@...com>,
Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>
Subject: Re: [PATCH RFC net-next 16/20] net/ipv6: Cleanup exception route handling
On Sun, Feb 25, 2018 at 11:47 AM, David Ahern <dsahern@...il.com> wrote:
> IPv6 FIB will only contain FIB entries with exception routes added to
> the FIB entry. Remove CACHE and dst checks from fib6 add and delete since
> they can never happen once the data type changes.
>
> Fixup the lookup functions to use a f6i name for fib lookups and retain
> the current rt name for return variables.
>
> Signed-off-by: David Ahern <dsahern@...il.com>
> ---
> net/ipv6/ip6_fib.c | 16 +------
> net/ipv6/route.c | 122 ++++++++++++++++++++++++++++++-----------------------
> 2 files changed, 71 insertions(+), 67 deletions(-)
>
> diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
> index 5b03f7e8d850..63a91db61749 100644
> --- a/net/ipv6/ip6_fib.c
> +++ b/net/ipv6/ip6_fib.c
> @@ -1046,7 +1046,7 @@ static int fib6_add_rt2node(struct fib6_node *fn, struct rt6_info *rt,
> static void fib6_start_gc(struct net *net, struct rt6_info *rt)
> {
> if (!timer_pending(&net->ipv6.ip6_fib_timer) &&
> - (rt->rt6i_flags & (RTF_EXPIRES | RTF_CACHE)))
> + (rt->rt6i_flags & RTF_EXPIRES))
> mod_timer(&net->ipv6.ip6_fib_timer,
> jiffies + net->ipv6.sysctl.ip6_rt_gc_interval);
> }
> @@ -1097,8 +1097,6 @@ int fib6_add(struct fib6_node *root, struct rt6_info *rt,
This rt here should be f6i?
>
> if (WARN_ON_ONCE(!atomic_read(&rt->dst.__refcnt)))
> return -EINVAL;
> - if (WARN_ON_ONCE(rt->rt6i_flags & RTF_CACHE))
> - return -EINVAL;
>
> if (info->nlh) {
> if (!(info->nlh->nlmsg_flags & NLM_F_CREATE))
> @@ -1622,8 +1620,6 @@ static void fib6_del_route(struct fib6_table *table, struct fib6_node *fn,
>
> RT6_TRACE("fib6_del_route\n");
>
> - WARN_ON_ONCE(rt->rt6i_flags & RTF_CACHE);
> -
> /* Unlink it */
> *rtp = rt->rt6_next;
This rt here is also f6i right?
> rt->rt6i_node = NULL;
> @@ -1692,21 +1688,11 @@ int fib6_del(struct rt6_info *rt, struct nl_info *info)
This rt here is also f6i right?
> struct rt6_info __rcu **rtp;
> struct rt6_info __rcu **rtp_next;
>
> -#if RT6_DEBUG >= 2
> - if (rt->dst.obsolete > 0) {
> - WARN_ON(fn);
> - return -ENOENT;
> - }
> -#endif
> if (!fn || rt == net->ipv6.fib6_null_entry)
> return -ENOENT;
>
> WARN_ON(!(fn->fn_flags & RTN_RTINFO));
>
> - /* remove cached dst from exception table */
> - if (rt->rt6i_flags & RTF_CACHE)
> - return rt6_remove_exception_rt(rt);
Could you help delete rt6_remove_exception_rt() function? I don't
think it is used anymore.
> -
> /*
> * Walk the leaf entries looking for ourself
> */
> diff --git a/net/ipv6/route.c b/net/ipv6/route.c
> index 3ea60e932eb9..19b91c60ee55 100644
> --- a/net/ipv6/route.c
> +++ b/net/ipv6/route.c
> @@ -1094,35 +1094,36 @@ static struct rt6_info *ip6_pol_route_lookup(struct net *net,
> struct fib6_table *table,
> struct flowi6 *fl6, int flags)
> {
> - struct rt6_info *rt, *rt_cache;
> + struct rt6_info *f6i;
> struct fib6_node *fn;
> + struct rt6_info *rt;
>
> rcu_read_lock();
> fn = fib6_lookup(&table->tb6_root, &fl6->daddr, &fl6->saddr);
> restart:
> - rt = rcu_dereference(fn->leaf);
> - if (!rt) {
> - rt = net->ipv6.fib6_null_entry;
> + f6i = rcu_dereference(fn->leaf);
> + if (!f6i) {
> + f6i = net->ipv6.fib6_null_entry;
> } else {
> - rt = rt6_device_match(net, rt, &fl6->saddr,
> + f6i = rt6_device_match(net, f6i, &fl6->saddr,
> fl6->flowi6_oif, flags);
> - if (rt->rt6i_nsiblings && fl6->flowi6_oif == 0)
> - rt = rt6_multipath_select(rt, fl6,
> + if (f6i->rt6i_nsiblings && fl6->flowi6_oif == 0)
> + f6i = rt6_multipath_select(f6i, fl6,
> fl6->flowi6_oif, flags);
> }
> - if (rt == net->ipv6.fib6_null_entry) {
> + if (f6i == net->ipv6.fib6_null_entry) {
> fn = fib6_backtrack(fn, &fl6->saddr);
> if (fn)
> goto restart;
> }
> +
> /* Search through exception table */
> - rt_cache = rt6_find_cached_rt(rt, &fl6->daddr, &fl6->saddr);
> - if (rt_cache) {
> - rt = rt_cache;
> + rt = rt6_find_cached_rt(f6i, &fl6->daddr, &fl6->saddr);
> + if (rt) {
> if (ip6_hold_safe(net, &rt, true))
> dst_use_noref(&rt->dst, jiffies);
> } else {
> - rt = ip6_create_rt_rcu(rt);
> + rt = ip6_create_rt_rcu(f6i);
> }
>
> rcu_read_unlock();
> @@ -1204,9 +1205,6 @@ static struct rt6_info *ip6_rt_cache_alloc(struct rt6_info *ort,
> * Clone the route.
> */
>
> - if (ort->rt6i_flags & (RTF_CACHE | RTF_PCPU))
> - ort = ort->from;
> -
> rcu_read_lock();
> dev = ip6_rt_get_dev_rcu(ort);
> rt = __ip6_dst_alloc(dev_net(dev), dev, 0);
> @@ -1432,11 +1430,6 @@ static int rt6_insert_exception(struct rt6_info *nrt,
Could you help change the second parameter name from ort to f6i for
rt6_insert_exception()? I think that makes it more readable.
> struct rt6_exception *rt6_ex;
> int err = 0;
>
> - /* ort can't be a cache or pcpu route */
> - if (ort->rt6i_flags & (RTF_CACHE | RTF_PCPU))
> - ort = ort->from;
> - WARN_ON_ONCE(ort->rt6i_flags & (RTF_CACHE | RTF_PCPU));
> -
> spin_lock_bh(&rt6_exception_lock);
>
> if (ort->exception_bucket_flushed) {
> @@ -1815,7 +1808,8 @@ struct rt6_info *ip6_pol_route(struct net *net, struct fib6_table *table,
> int oif, struct flowi6 *fl6, int flags)
> {
> struct fib6_node *fn, *saved_fn;
> - struct rt6_info *rt, *rt_cache;
> + struct rt6_info *f6i;
> + struct rt6_info *rt;
> int strict = 0;
>
> strict |= flags & RT6_LOOKUP_F_IFACE;
> @@ -1832,10 +1826,10 @@ struct rt6_info *ip6_pol_route(struct net *net, struct fib6_table *table,
> oif = 0;
>
> redo_rt6_select:
> - rt = rt6_select(net, fn, oif, strict);
> - if (rt->rt6i_nsiblings)
> - rt = rt6_multipath_select(rt, fl6, oif, strict);
> - if (rt == net->ipv6.fib6_null_entry) {
> + f6i = rt6_select(net, fn, oif, strict);
> + if (f6i->rt6i_nsiblings)
> + f6i = rt6_multipath_select(f6i, fl6, oif, strict);
> + if (f6i == net->ipv6.fib6_null_entry) {
> fn = fib6_backtrack(fn, &fl6->saddr);
> if (fn)
> goto redo_rt6_select;
> @@ -1847,18 +1841,17 @@ struct rt6_info *ip6_pol_route(struct net *net, struct fib6_table *table,
> }
> }
>
> - /*Search through exception table */
> - rt_cache = rt6_find_cached_rt(rt, &fl6->daddr, &fl6->saddr);
> - if (rt_cache)
> - rt = rt_cache;
> -
> - if (rt == net->ipv6.fib6_null_entry) {
> + if (f6i == net->ipv6.fib6_null_entry) {
> rt = net->ipv6.ip6_null_entry;
> rcu_read_unlock();
> dst_hold(&rt->dst);
> trace_fib6_table_lookup(net, rt, table, fl6);
> return rt;
> - } else if (rt->rt6i_flags & RTF_CACHE) {
> + }
> +
> + /*Search through exception table */
> + rt = rt6_find_cached_rt(f6i, &fl6->daddr, &fl6->saddr);
Could you help change the first paramter name from rt to f6i in the
function definition of rt6_find_cached_rt() as well?
> + if (rt) {
> if (ip6_hold_safe(net, &rt, true))
> dst_use_noref(&rt->dst, jiffies);
>
> @@ -1866,7 +1859,7 @@ struct rt6_info *ip6_pol_route(struct net *net, struct fib6_table *table,
> trace_fib6_table_lookup(net, rt, table, fl6);
> return rt;
> } else if (unlikely((fl6->flowi6_flags & FLOWI_FLAG_KNOWN_NH) &&
> - !(rt->rt6i_flags & RTF_GATEWAY))) {
> + !(f6i->rt6i_flags & RTF_GATEWAY))) {
> /* Create a RTF_CACHE clone which will not be
> * owned by the fib6 tree. It is for the special case where
> * the daddr in the skb during the neighbor look-up is different
> @@ -1875,16 +1868,16 @@ struct rt6_info *ip6_pol_route(struct net *net, struct fib6_table *table,
>
> struct rt6_info *uncached_rt;
>
> - if (ip6_hold_safe(net, &rt, true)) {
> - dst_use_noref(&rt->dst, jiffies);
> + if (ip6_hold_safe(net, &f6i, true)) {
> + dst_use_noref(&f6i->dst, jiffies);
> } else {
> rcu_read_unlock();
> - uncached_rt = rt;
> + uncached_rt = f6i;
> goto uncached_rt_out;
> }
> rcu_read_unlock();
>
> - uncached_rt = ip6_rt_cache_alloc(rt, &fl6->daddr, NULL);
> + uncached_rt = ip6_rt_cache_alloc(f6i, &fl6->daddr, NULL);
> dst_release(&rt->dst);
>
> if (uncached_rt) {
> @@ -1907,18 +1900,18 @@ struct rt6_info *ip6_pol_route(struct net *net, struct fib6_table *table,
>
> struct rt6_info *pcpu_rt;
>
> - dst_use_noref(&rt->dst, jiffies);
> + dst_use_noref(&f6i->dst, jiffies);
> local_bh_disable();
> - pcpu_rt = rt6_get_pcpu_route(rt);
> + pcpu_rt = rt6_get_pcpu_route(f6i);
>
> if (!pcpu_rt) {
> /* atomic_inc_not_zero() is needed when using rcu */
> - if (atomic_inc_not_zero(&rt->rt6i_ref)) {
> + if (atomic_inc_not_zero(&f6i->rt6i_ref)) {
> /* No dst_hold() on rt is needed because grabbing
> * rt->rt6i_ref makes sure rt can't be released.
> */
> - pcpu_rt = rt6_make_pcpu_route(net, rt);
> - rt6_release(rt);
> + pcpu_rt = rt6_make_pcpu_route(net, f6i);
> + rt6_release(f6i);
> } else {
> /* rt is already removed from tree */
> pcpu_rt = net->ipv6.ip6_null_entry;
> @@ -2296,7 +2289,8 @@ static struct rt6_info *__ip6_route_redirect(struct net *net,
> int flags)
> {
> struct ip6rd_flowi *rdfl = (struct ip6rd_flowi *)fl6;
> - struct rt6_info *rt, *rt_cache;
> + struct rt6_info *ret = NULL, *rt_cache;
> + struct rt6_info *rt;
> struct fib6_node *fn;
>
> /* Get the "current" route for this destination and
> @@ -2335,7 +2329,7 @@ static struct rt6_info *__ip6_route_redirect(struct net *net,
> if (rt_cache &&
> ipv6_addr_equal(&rdfl->gateway,
> &rt_cache->rt6i_gateway)) {
> - rt = rt_cache;
> + ret = rt_cache;
> break;
> }
> continue;
> @@ -2346,7 +2340,7 @@ static struct rt6_info *__ip6_route_redirect(struct net *net,
> if (!rt)
> rt = net->ipv6.fib6_null_entry;
> else if (rt->rt6i_flags & RTF_REJECT) {
> - rt = net->ipv6.ip6_null_entry;
> + ret = net->ipv6.ip6_null_entry;
> goto out;
> }
>
> @@ -2357,12 +2351,15 @@ static struct rt6_info *__ip6_route_redirect(struct net *net,
> }
>
> out:
> - ip6_hold_safe(net, &rt, true);
> + if (ret)
> + dst_hold(&ret->dst);
> + else
> + ret = ip6_create_rt_rcu(rt);
>
> rcu_read_unlock();
>
> - trace_fib6_table_lookup(net, rt, table, fl6);
> - return rt;
> + trace_fib6_table_lookup(net, ret, table, fl6);
> + return ret;
> };
>
> static struct dst_entry *ip6_route_redirect(struct net *net,
> @@ -3031,6 +3028,22 @@ static int __ip6_del_rt_siblings(struct rt6_info *rt, struct fib6_config *cfg)
> return err;
> }
>
> +static int ip6_del_cached_rt(struct rt6_info *rt, struct fib6_config *cfg)
> +{
> + int rc = -ESRCH;
> +
> + if (cfg->fc_ifindex && rt->dst.dev->ifindex != cfg->fc_ifindex)
> + goto out;
> +
> + if (cfg->fc_flags & RTF_GATEWAY &&
> + !ipv6_addr_equal(&cfg->fc_gateway, &rt->rt6i_gateway))
> + goto out;
> + if (dst_hold_safe(&rt->dst))
> + rc = rt6_remove_exception_rt(rt);
> +out:
> + return rc;
> +}
> +
> static int ip6_route_del(struct fib6_config *cfg,
> struct netlink_ext_ack *extack)
> {
> @@ -3055,11 +3068,16 @@ static int ip6_route_del(struct fib6_config *cfg,
> if (fn) {
> for_each_fib6_node_rt_rcu(fn) {
> if (cfg->fc_flags & RTF_CACHE) {
> + int rc;
> +
> rt_cache = rt6_find_cached_rt(rt, &cfg->fc_dst,
> &cfg->fc_src);
Here "rt" should also be renamed to "f6i"? Probably need to update
for_each_fib6_node_rt_rcu() macro to use f6i instead of rt.
> - if (!rt_cache)
> - continue;
> - rt = rt_cache;
> + if (rt_cache) {
> + rc = ip6_del_cached_rt(rt_cache, cfg);
> + if (rc != -ESRCH)
> + return rc;
> + }
> + continue;
> }
> if (cfg->fc_ifindex &&
> (!rt->fib6_nh.nh_dev ||
> @@ -3176,7 +3194,7 @@ static void rt6_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_bu
> NEIGH_UPDATE_F_ISROUTER)),
> NDISC_REDIRECT, &ndopts);
>
> - nrt = ip6_rt_cache_alloc(rt, &msg->dest, NULL);
> + nrt = ip6_rt_cache_alloc(rt->from, &msg->dest, NULL);
> goto out;
>
> --
> 2.11.0
>
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