net: sched: cls_u32: Undo refcount decrement in case update failed

[ Upstream commit e8d3d78c19be0264a5692bed477c303523aead31 ]

In the case of an update, when TCA_U32_LINK is set, u32_set_parms will
decrement the refcount of the ht_down (struct tc_u_hnode) pointer
present in the older u32 filter which we are replacing. However, if
u32_replace_hw_knode errors out, the update command fails and that
ht_down pointer continues decremented. To fix that, when
u32_replace_hw_knode fails, check if ht_down's refcount was decremented
and undo the decrement.

Fixes: d34e3e181395 ("net: cls_u32: Add support for skip-sw flag to tc u32 classifier.")
Signed-off-by: Victor Nogueira <victor@mojatatu.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Reviewed-by: Pedro Tammela <pctammela@mojatatu.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/sched/cls_u32.c b/net/sched/cls_u32.c
index 7cfbcd5..1280736 100644 (file)
--- a/net/sched/cls_u32.c
+++ b/net/sched/cls_u32.c
@@ -926,6 +926,13 @@ static int u32_change(struct net *net, struct sk_buff *in_skb,
                if (err) {
                        u32_unbind_filter(tp, new, tb);
 
+                       if (tb[TCA_U32_LINK]) {
+                               struct tc_u_hnode *ht_old;
+
+                               ht_old = rtnl_dereference(n->ht_down);
+                               if (ht_old)
+                                       ht_old->refcnt++;
+                       }
                        __u32_destroy_key(new);
                        return err;
                }