Commit c8cbe123 authored Sep 15, 2022 by Vladimir Oltean Committed by Jakub Kicinski Sep 20, 2022

net/sched: taprio: taprio_offload_config_changed() is protected by rtnl_mutex



The locking in taprio_offload_config_changed() is wrong (but also
inconsequentially so). The current_entry_lock does not serialize changes
to the admin and oper schedules, only to the current entry. In fact, the
rtnl_mutex does that, and that is taken at the time when taprio_change()
is called.

Replace the rcu_dereference_protected() method with the proper RCU
annotation, and drop the unnecessary spin lock.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

parent 4d3c8848

net/sched/sch_taprio.c

+2 −8

Original line number	Diff line number	Diff line
		@@ -1193,16 +1193,10 @@ static void taprio_offload_config_changed(struct taprio_sched *q)
		{
		struct sched_gate_list oper, admin;

		spin_lock(&q->current_entry_lock);

		oper = rcu_dereference_protected(q->oper_sched,
		lockdep_is_held(&q->current_entry_lock));
		admin = rcu_dereference_protected(q->admin_sched,
		lockdep_is_held(&q->current_entry_lock));
		oper = rtnl_dereference(q->oper_sched);
		admin = rtnl_dereference(q->admin_sched);

		switch_schedules(q, &admin, &oper);

		spin_unlock(&q->current_entry_lock);
		}

		static u32 tc_map_to_queue_mask(struct net_device *dev, u32 tc_mask)