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Commit 75de9113 authored by Johannes Berg's avatar Johannes Berg
Browse files

mac80211: optimise AP stop RCU handling 



If there are VLANs, stopping an AP is inefficient as it
calls rcu_barrier() once for each interface (the VLANs
and the AP itself). Optimise this by moving rcu_barrier()
out of the station cleanups and calling it only once for
all interfaces combined.

Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
parent 361c9c8b

net/mac80211/cfg.c

+7 −2
Original line number Diff line number Diff line
@@ -1010,8 +1010,13 @@ static int ieee80211_stop_ap(struct wiphy *wiphy, struct net_device *dev) 
		kfree_rcu(old_probe_resp, rcu_head);



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

		sta_info_flush(vlan);

	sta_info_flush(sdata);

		sta_info_flush_defer(vlan);

	sta_info_flush_defer(sdata);

	rcu_barrier();

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

		sta_info_flush_cleanup(vlan);

	sta_info_flush_cleanup(sdata);



	ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_BEACON_ENABLED);



	drv_stop_ap(sdata->local, sdata);

net/mac80211/iface.c

+8 −5
Original line number Diff line number Diff line
@@ -863,12 +863,15 @@ static void ieee80211_do_stop(struct ieee80211_sub_if_data *sdata, 
		cancel_work_sync(&sdata->work);

		/*

		 * When we get here, the interface is marked down.

		 * sta_info_flush_cleanup() calls rcu_barrier to

		 * wait for the station call_rcu() calls to complete,

		 * here we require it to wait for the RX path in case

		 * it is using the interface and enqueuing frames at

		 * this very time on another CPU.

		 *

		 * 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

		 * interface and enqueuing frames at this very time on

		 * another CPU.

		 */

		rcu_barrier();

		sta_info_flush_cleanup(sdata);



		skb_queue_purge(&sdata->skb_queue);

net/mac80211/sta_info.c

+0 −2
Original line number Diff line number Diff line
@@ -920,8 +920,6 @@ int sta_info_flush_defer(struct ieee80211_sub_if_data *sdata) 


void sta_info_flush_cleanup(struct ieee80211_sub_if_data *sdata)

{

	rcu_barrier();



	ieee80211_cleanup_sdata_stas(sdata);

	cancel_work_sync(&sdata->cleanup_stations_wk);

}

net/mac80211/sta_info.h

+14 −0
Original line number Diff line number Diff line
@@ -549,6 +549,19 @@ void sta_info_recalc_tim(struct sta_info *sta); 
void sta_info_init(struct ieee80211_local *local);

void sta_info_stop(struct ieee80211_local *local);

int sta_info_flush_defer(struct ieee80211_sub_if_data *sdata);



/**

 * sta_info_flush_cleanup - flush the sta_info cleanup queue

 * @sdata: the interface

 *

 * Flushes the sta_info cleanup queue for a given interface;

 * this is necessary before the interface is removed or, for

 * AP/mesh interfaces, before it is deconfigured.

 *

 * Note an rcu_barrier() must precede the function, after all

 * stations have been flushed/removed to ensure the call_rcu()

 * calls that add stations to the cleanup queue have completed.

 */

void sta_info_flush_cleanup(struct ieee80211_sub_if_data *sdata);



/**
@@ -562,6 +575,7 @@ static inline int sta_info_flush(struct ieee80211_sub_if_data *sdata) 
{

	int ret = sta_info_flush_defer(sdata);



	rcu_barrier();

	sta_info_flush_cleanup(sdata);



	return ret;