netdev - [patch net-next] net: sched: fix flush on non-existing chain

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Message-Id: <20180803090847.1199-1-jiri@resnulli.us>
Date:   Fri,  3 Aug 2018 11:08:47 +0200
From:   Jiri Pirko <jiri@...nulli.us>
To:     netdev@...r.kernel.org
Cc:     davem@...emloft.net, jhs@...atatu.com, xiyou.wangcong@...il.com,
        jakub.kicinski@...ronome.com, idosch@...lanox.com,
        mlxsw@...lanox.com
Subject: [patch net-next] net: sched: fix flush on non-existing chain

From: Jiri Pirko <jiri@...lanox.com>

User was able to perform filter flush on chain 0 even if it didn't have
any filters in it. With the patch that avoided implicit chain 0
creation, this changed. So in case user wants filter flush on chain
which does not exist, just return success. There's no reason for non-0
chains to behave differently than chain 0, so do the same for them.

Reported-by: Ido Schimmel <idosch@...lanox.com>
Fixes: f71e0ca4db18 ("net: sched: Avoid implicit chain 0 creation")
Signed-off-by: Jiri Pirko <jiri@...lanox.com>
---
 net/sched/cls_api.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index e8b0bbd0883f..194c2e0b2737 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -1389,6 +1389,13 @@ static int tc_del_tfilter(struct sk_buff *skb, struct nlmsghdr *n,
 	}
 	chain = tcf_chain_get(block, chain_index, false);
 	if (!chain) {
+		/* User requested flush on non-existent chain. Nothing to do,
+		 * so just return success.
+		 */
+		if (prio == 0) {
+			err = 0;
+			goto errout;
+		}
 		NL_SET_ERR_MSG(extack, "Cannot find specified filter chain");
 		err = -EINVAL;
 		goto errout;
-- 
2.14.4