[PATCH 02/12] Revert "net/sched: Restrict conditions for adding duplicating netems to qdisc tree"

[Stephen Hemminger <stephen@networkplumber.org>]

This reverts commit ec8e0e3d7adef940cdf9475e2352c0680189d14e.

The restriction breaks valid uses of netem such as using different
netem values on different branches of HTB. This even broke some
of the examples in the netem documentation.

The intent of blocking recursion is handled in next patch.

Fixes: ec8e0e3d7adef ("net/sched: Restrict conditions for adding duplicating netems to qdisc tree")
Reported-by: Ji-Soo Chung <jschung2@proton.me>
Reported-by: Gerlinde <lrGerlinde@mailfence.com>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=220774
Cc: stable@vger.kernel.org
Originally-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 net/sched/sch_netem.c | 40 ----------------------------------------
 1 file changed, 40 deletions(-)

diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index 5de1c932944a..0ccf74a9cb82 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -974,41 +974,6 @@ static int parse_attr(struct nlattr *tb[], int maxtype, struct nlattr *nla,
 	return 0;
 }
 
-static const struct Qdisc_class_ops netem_class_ops;
-
-static int check_netem_in_tree(struct Qdisc *sch, bool duplicates,
-			       struct netlink_ext_ack *extack)
-{
-	struct Qdisc *root, *q;
-	unsigned int i;
-
-	root = qdisc_root_sleeping(sch);
-
-	if (sch != root && root->ops->cl_ops == &netem_class_ops) {
-		if (duplicates ||
-		    ((struct netem_sched_data *)qdisc_priv(root))->duplicate)
-			goto err;
-	}
-
-	if (!qdisc_dev(root))
-		return 0;
-
-	hash_for_each(qdisc_dev(root)->qdisc_hash, i, q, hash) {
-		if (sch != q && q->ops->cl_ops == &netem_class_ops) {
-			if (duplicates ||
-			    ((struct netem_sched_data *)qdisc_priv(q))->duplicate)
-				goto err;
-		}
-	}
-
-	return 0;
-
-err:
-	NL_SET_ERR_MSG(extack,
-		       "netem: cannot mix duplicating netems with other netems in tree");
-	return -EINVAL;
-}
-
 /* Parse netlink message to set options */
 static int netem_change(struct Qdisc *sch, struct nlattr *opt,
 			struct netlink_ext_ack *extack)
@@ -1067,11 +1032,6 @@ static int netem_change(struct Qdisc *sch, struct nlattr *opt,
 	q->gap = qopt->gap;
 	q->counter = 0;
 	q->loss = qopt->loss;
-
-	ret = check_netem_in_tree(sch, qopt->duplicate, extack);
-	if (ret)
-		goto unlock;
-
 	q->duplicate = qopt->duplicate;
 
 	/* for compatibility with earlier versions.
-- 
2.51.0