ipv6: Remove BACKTRACK macro
It is the prep work to reduce the number of calls to fib6_lookup(). The BACKTRACK macro could be hard-to-read and error-prone due to its side effects (mainly goto). This patch is to: 1. Replace BACKTRACK macro with a function (fib6_backtrack) with the following return values: * If it is backtrack-able, returns next fn for retry. * If it reaches the root, returns NULL. 2. The caller needs to decide if a backtrack is needed (by testing rt == net->ipv6.ip6_null_entry). 3. Rename the goto labels in ip6_pol_route() to make the next few patches easier to read. Cc: David Miller <davem@davemloft.net> Cc: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -772,23 +772,22 @@ int rt6_route_rcv(struct net_device *dev, u8 *opt, int len,
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}
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#endif
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#define BACKTRACK(__net, saddr) \
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do { \
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if (rt == __net->ipv6.ip6_null_entry) { \
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struct fib6_node *pn; \
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while (1) { \
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if (fn->fn_flags & RTN_TL_ROOT) \
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goto out; \
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pn = fn->parent; \
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if (FIB6_SUBTREE(pn) && FIB6_SUBTREE(pn) != fn) \
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fn = fib6_lookup(FIB6_SUBTREE(pn), NULL, saddr); \
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else \
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fn = pn; \
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if (fn->fn_flags & RTN_RTINFO) \
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goto restart; \
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} \
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} \
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} while (0)
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static struct fib6_node* fib6_backtrack(struct fib6_node *fn,
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struct in6_addr *saddr)
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{
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struct fib6_node *pn;
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while (1) {
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if (fn->fn_flags & RTN_TL_ROOT)
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return NULL;
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pn = fn->parent;
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if (FIB6_SUBTREE(pn) && FIB6_SUBTREE(pn) != fn)
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fn = fib6_lookup(FIB6_SUBTREE(pn), NULL, saddr);
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else
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fn = pn;
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if (fn->fn_flags & RTN_RTINFO)
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return fn;
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}
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}
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static struct rt6_info *ip6_pol_route_lookup(struct net *net,
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struct fib6_table *table,
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@ -804,8 +803,11 @@ static struct rt6_info *ip6_pol_route_lookup(struct net *net,
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rt = rt6_device_match(net, rt, &fl6->saddr, fl6->flowi6_oif, flags);
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if (rt->rt6i_nsiblings && fl6->flowi6_oif == 0)
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rt = rt6_multipath_select(rt, fl6, fl6->flowi6_oif, flags);
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BACKTRACK(net, &fl6->saddr);
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out:
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if (rt == net->ipv6.ip6_null_entry) {
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fn = fib6_backtrack(fn, &fl6->saddr);
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if (fn)
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goto restart;
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}
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dst_use(&rt->dst, jiffies);
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read_unlock_bh(&table->tb6_lock);
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return rt;
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@ -924,19 +926,25 @@ static struct rt6_info *ip6_pol_route(struct net *net, struct fib6_table *table,
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strict |= flags & RT6_LOOKUP_F_IFACE;
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relookup:
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redo_fib6_lookup_lock:
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read_lock_bh(&table->tb6_lock);
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restart_2:
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redo_fib6_lookup:
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fn = fib6_lookup(&table->tb6_root, &fl6->daddr, &fl6->saddr);
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restart:
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redo_rt6_select:
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rt = rt6_select(fn, oif, strict | reachable);
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if (rt->rt6i_nsiblings)
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rt = rt6_multipath_select(rt, fl6, oif, strict | reachable);
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BACKTRACK(net, &fl6->saddr);
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if (rt == net->ipv6.ip6_null_entry ||
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rt->rt6i_flags & RTF_CACHE)
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if (rt == net->ipv6.ip6_null_entry) {
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fn = fib6_backtrack(fn, &fl6->saddr);
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if (fn)
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goto redo_rt6_select;
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else
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goto out;
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}
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if (rt->rt6i_flags & RTF_CACHE)
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goto out;
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dst_hold(&rt->dst);
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@ -967,12 +975,12 @@ static struct rt6_info *ip6_pol_route(struct net *net, struct fib6_table *table,
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* released someone could insert this route. Relookup.
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*/
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ip6_rt_put(rt);
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goto relookup;
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goto redo_fib6_lookup_lock;
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out:
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if (reachable) {
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reachable = 0;
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goto restart_2;
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goto redo_fib6_lookup;
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}
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dst_hold(&rt->dst);
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read_unlock_bh(&table->tb6_lock);
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@ -1235,10 +1243,12 @@ static struct rt6_info *__ip6_route_redirect(struct net *net,
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rt = net->ipv6.ip6_null_entry;
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else if (rt->dst.error) {
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rt = net->ipv6.ip6_null_entry;
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goto out;
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} else if (rt == net->ipv6.ip6_null_entry) {
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fn = fib6_backtrack(fn, &fl6->saddr);
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if (fn)
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goto restart;
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}
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BACKTRACK(net, &fl6->saddr);
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out:
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dst_hold(&rt->dst);
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read_unlock_bh(&table->tb6_lock);
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