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Commit 8ceb5955 authored by Bob Copeland's avatar Bob Copeland Committed by Johannes Berg
Browse files

mac80211: use synchronize_rcu() with rcu_barrier() 



The RCU docs used to state that rcu_barrier() included a wait
for an RCU grace period; however the comments for rcu_barrier()
as of commit f0a0e6f2... "rcu: Clarify memory-ordering properties
of grace-period primitives" contradict this.

So add back synchronize_{rcu,net}() to where they once were,
but keep the rcu_barrier()s for the call_rcu() callbacks.

Cc: stable <stable@vger.kernel.org>
Signed-off-by: default avatarBob Copeland <bob@cozybit.com>
Reviewed-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
parent 908f8d07

net/mac80211/cfg.c

+1 −0
Original line number Diff line number Diff line
@@ -1043,6 +1043,7 @@ static int ieee80211_stop_ap(struct wiphy *wiphy, struct net_device *dev) 
	list_for_each_entry(vlan, &sdata->u.ap.vlans, u.vlan.list)

		sta_info_flush_defer(vlan);

	sta_info_flush_defer(sdata);

	synchronize_net();

	rcu_barrier();

	list_for_each_entry(vlan, &sdata->u.ap.vlans, u.vlan.list) {

		sta_info_flush_cleanup(vlan);

net/mac80211/iface.c

+3 −2
Original line number Diff line number Diff line
@@ -839,11 +839,12 @@ static void ieee80211_do_stop(struct ieee80211_sub_if_data *sdata, 
		 *

		 * sta_info_flush_cleanup() requires rcu_barrier()

		 * first to wait for the station call_rcu() calls

		 * to complete, here we need at least sychronize_rcu()

		 * it to wait for the RX path in case it is using the

		 * to complete, and we also need synchronize_rcu()

		 * to wait for the RX path in case it is using the

		 * interface and enqueuing frames at this very time on

		 * another CPU.

		 */

		synchronize_rcu();

		rcu_barrier();

		sta_info_flush_cleanup(sdata);

net/mac80211/pm.c

+1 −0
Original line number Diff line number Diff line
@@ -38,6 +38,7 @@ int __ieee80211_suspend(struct ieee80211_hw *hw, struct cfg80211_wowlan *wowlan) 
					IEEE80211_QUEUE_STOP_REASON_SUSPEND);



	/* flush out all packets and station cleanup call_rcu()s */

	synchronize_net();

	rcu_barrier();



	ieee80211_flush_queues(local, NULL);