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ipv6: Remove BACKTRACK macro

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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>
This commit is contained in:
Martin KaFai Lau 2014-10-20 13:42:43 -07:00 committed by David S. Miller
parent 105970f608
commit a3c00e46ef
1 changed files with 40 additions and 30 deletions
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70
net/ipv6/route.c
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@ -772,23 +772,22 @@ int rt6_route_rcv(struct net_device *dev, u8 *opt, int len,
}
#endif
#define BACKTRACK(__net, saddr) \
do { \
if (rt == __net->ipv6.ip6_null_entry) { \
struct fib6_node *pn; \
while (1) { \
if (fn->fn_flags & RTN_TL_ROOT) \
goto out; \
pn = fn->parent; \
if (FIB6_SUBTREE(pn) && FIB6_SUBTREE(pn) != fn) \
fn = fib6_lookup(FIB6_SUBTREE(pn), NULL, saddr); \
else \
fn = pn; \
if (fn->fn_flags & RTN_RTINFO) \
goto restart; \
} \
} \
} while (0)
static struct fib6_node* fib6_backtrack(struct fib6_node *fn,
struct in6_addr *saddr)
{
struct fib6_node *pn;
while (1) {
if (fn->fn_flags & RTN_TL_ROOT)
return NULL;
pn = fn->parent;
if (FIB6_SUBTREE(pn) && FIB6_SUBTREE(pn) != fn)
fn = fib6_lookup(FIB6_SUBTREE(pn), NULL, saddr);
else
fn = pn;
if (fn->fn_flags & RTN_RTINFO)
return fn;
}
}
static struct rt6_info *ip6_pol_route_lookup(struct net *net,
struct fib6_table *table,
@ -804,8 +803,11 @@ restart:
rt = rt6_device_match(net, rt, &fl6->saddr, fl6->flowi6_oif, flags);
if (rt->rt6i_nsiblings && fl6->flowi6_oif == 0)
rt = rt6_multipath_select(rt, fl6, fl6->flowi6_oif, flags);
BACKTRACK(net, &fl6->saddr);
out:
if (rt == net->ipv6.ip6_null_entry) {
fn = fib6_backtrack(fn, &fl6->saddr);
if (fn)
goto restart;
}
dst_use(&rt->dst, jiffies);
read_unlock_bh(&table->tb6_lock);
return rt;
@ -924,19 +926,25 @@ static struct rt6_info *ip6_pol_route(struct net *net, struct fib6_table *table,
strict |= flags & RT6_LOOKUP_F_IFACE;
relookup:
redo_fib6_lookup_lock:
read_lock_bh(&table->tb6_lock);
restart_2:
redo_fib6_lookup:
fn = fib6_lookup(&table->tb6_root, &fl6->daddr, &fl6->saddr);
restart:
redo_rt6_select:
rt = rt6_select(fn, oif, strict | reachable);
if (rt->rt6i_nsiblings)
rt = rt6_multipath_select(rt, fl6, oif, strict | reachable);
BACKTRACK(net, &fl6->saddr);
if (rt == net->ipv6.ip6_null_entry ||
rt->rt6i_flags & RTF_CACHE)
if (rt == net->ipv6.ip6_null_entry) {
fn = fib6_backtrack(fn, &fl6->saddr);
if (fn)
goto redo_rt6_select;
else
goto out;
}
if (rt->rt6i_flags & RTF_CACHE)
goto out;
dst_hold(&rt->dst);
@ -967,12 +975,12 @@ restart:
* released someone could insert this route. Relookup.
*/
ip6_rt_put(rt);
goto relookup;
goto redo_fib6_lookup_lock;
out:
if (reachable) {
reachable = 0;
goto restart_2;
goto redo_fib6_lookup;
}
dst_hold(&rt->dst);
read_unlock_bh(&table->tb6_lock);
@ -1235,10 +1243,12 @@ restart:
rt = net->ipv6.ip6_null_entry;
else if (rt->dst.error) {
rt = net->ipv6.ip6_null_entry;
goto out;
} else if (rt == net->ipv6.ip6_null_entry) {
fn = fib6_backtrack(fn, &fl6->saddr);
if (fn)
goto restart;
}
BACKTRACK(net, &fl6->saddr);
out:
dst_hold(&rt->dst);
read_unlock_bh(&table->tb6_lock);