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Date: Mon, 20 Oct 2014 13:42:43 -0700
From: Martin KaFai Lau <kafai@...com>
To: <netdev@...r.kernel.org>
CC: David Miller <davem@...emloft.net>,
Hannes Frederic Sowa <hannes@...essinduktion.org>
Subject: [PATCH RFC v5 net 1/3] 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@...emloft.net>
Cc: Hannes Frederic Sowa <hannes@...essinduktion.org>
Signed-off-by: Martin KaFai Lau <kafai@...com>
---
net/ipv6/route.c | 70 ++++++++++++++++++++++++++++++++------------------------
1 file changed, 40 insertions(+), 30 deletions(-)
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index a318dd89..f1ab2f4 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -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);
--
1.8.1
--
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