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Subject[patch 16/38] IPV4: fib: fix route replacement, fib_info is shared
2.6.24-stable review patch.  If anyone has any objections, please let us
know.

------------------
Upstream commit: c18865f39276435abb9286f9a816cb5b66c99a00
fib_info can be shared by many route prefixes but we don't want
duplicate alternative routes for a prefix+tos+priority. Last change
was not correct to check fib_treeref because it accounts usage from
other prefixes. Additionally, avoid replacement without error if new
route is same, as Joonwoo Park suggests.

Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
net/ipv4/fib_hash.c | 47 +++++++++++++++++++++++++++++++----------------
1 file changed, 31 insertions(+), 16 deletions(-)
--- a/net/ipv4/fib_hash.c
+++ b/net/ipv4/fib_hash.c
@@ -434,19 +434,43 @@ static int fn_hash_insert(struct fib_tab

if (fa && fa->fa_tos == tos &&
fa->fa_info->fib_priority == fi->fib_priority) {
- struct fib_alias *fa_orig;
+ struct fib_alias *fa_first, *fa_match;

err = -EEXIST;
if (cfg->fc_nlflags & NLM_F_EXCL)
goto out;

+ /* We have 2 goals:
+ * 1. Find exact match for type, scope, fib_info to avoid
+ * duplicate routes
+ * 2. Find next 'fa' (or head), NLM_F_APPEND inserts before it
+ */
+ fa_match = NULL;
+ fa_first = fa;
+ fa = list_entry(fa->fa_list.prev, struct fib_alias, fa_list);
+ list_for_each_entry_continue(fa, &f->fn_alias, fa_list) {
+ if (fa->fa_tos != tos)
+ break;
+ if (fa->fa_info->fib_priority != fi->fib_priority)
+ break;
+ if (fa->fa_type == cfg->fc_type &&
+ fa->fa_scope == cfg->fc_scope &&
+ fa->fa_info == fi) {
+ fa_match = fa;
+ break;
+ }
+ }
+
if (cfg->fc_nlflags & NLM_F_REPLACE) {
struct fib_info *fi_drop;
u8 state;

- if (fi->fib_treeref > 1)
+ fa = fa_first;
+ if (fa_match) {
+ if (fa == fa_match)
+ err = 0;
goto out;
-
+ }
write_lock_bh(&fib_hash_lock);
fi_drop = fa->fa_info;
fa->fa_info = fi;
@@ -469,20 +493,11 @@ static int fn_hash_insert(struct fib_tab
* uses the same scope, type, and nexthop
* information.
*/
- fa_orig = fa;
- fa = list_entry(fa->fa_list.prev, struct fib_alias, fa_list);
- list_for_each_entry_continue(fa, &f->fn_alias, fa_list) {
- if (fa->fa_tos != tos)
- break;
- if (fa->fa_info->fib_priority != fi->fib_priority)
- break;
- if (fa->fa_type == cfg->fc_type &&
- fa->fa_scope == cfg->fc_scope &&
- fa->fa_info == fi)
- goto out;
- }
+ if (fa_match)
+ goto out;
+
if (!(cfg->fc_nlflags & NLM_F_APPEND))
- fa = fa_orig;
+ fa = fa_first;
}

err = -ENOENT;
--


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