From: Cong Wang <xiyou.wangcong@gmail.com>
Date: Tue, 19 Sep 2017 13:15:42 -0700
Subject: net_sched: no need to free qdisc in RCU callback
Patch-mainline: v4.15-rc1
Git-commit: 752fbcc33405d6f8249465e4b2c4e420091bb825
References: bsc#1109837

gen estimator has been rewritten in commit 1c0d32fde5bd
("net_sched: gen_estimator: complete rewrite of rate estimators"),
the caller no longer needs to wait for a grace period. So this
patch gets rid of it.

Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Eric Dumazet <edumazet@google.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 include/net/sch_generic.h |    1 -
 net/sched/sch_generic.c   |   10 ++--------
 2 files changed, 2 insertions(+), 9 deletions(-)

--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -94,7 +94,6 @@ struct Qdisc {
 	unsigned long		state;
 	struct Qdisc            *next_sched;
 	struct sk_buff		*skb_bad_txq;
-	struct rcu_head		rcu_head;
 	int			padded;
 	refcount_t		refcnt;
 
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -685,10 +685,8 @@ void qdisc_reset(struct Qdisc *qdisc)
 }
 EXPORT_SYMBOL(qdisc_reset);
 
-static void qdisc_rcu_free(struct rcu_head *head)
+static void qdisc_free(struct Qdisc *qdisc)
 {
-	struct Qdisc *qdisc = container_of(head, struct Qdisc, rcu_head);
-
 	if (qdisc_is_percpu_stats(qdisc)) {
 		free_percpu(qdisc->cpu_bstats);
 		free_percpu(qdisc->cpu_qstats);
@@ -721,11 +719,7 @@ void qdisc_destroy(struct Qdisc *qdisc)
 
 	kfree_skb_list(qdisc->gso_skb);
 	kfree_skb(qdisc->skb_bad_txq);
-	/*
-	 * gen_estimator est_timer() might access qdisc->q.lock,
-	 * wait a RCU grace period before freeing qdisc.
-	 */
-	call_rcu(&qdisc->rcu_head, qdisc_rcu_free);
+	qdisc_free(qdisc);
 }
 EXPORT_SYMBOL(qdisc_destroy);