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Commit 051007d9 authored by Johannes Berg's avatar Johannes Berg
Browse files

mac80211: optimise roaming time again 



The last fixes re-added the RCU synchronize penalty
on roaming to fix the races. Split up sta_info_flush()
now to get rid of that again, and let managed mode
(and only it) delay the actual destruction.

Tested-by: default avatarBen Greear <greearb@candelatech.com>
Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
parent 09f4114e

net/mac80211/iface.c

+10 −5
Original line number Diff line number Diff line
@@ -775,8 +775,10 @@ static void ieee80211_do_stop(struct ieee80211_sub_if_data *sdata, 
	 * This is relevant only in WDS mode, in all other modes we've

	 * already removed all stations when disconnecting or similar,

	 * so warn otherwise.

	 *

	 * We call sta_info_flush_cleanup() later, to combine RCU waits.

	 */

	flushed = sta_info_flush(sdata);

	flushed = sta_info_flush_defer(sdata);

	WARN_ON_ONCE((sdata->vif.type != NL80211_IFTYPE_WDS && flushed > 0) ||

		     (sdata->vif.type == NL80211_IFTYPE_WDS && flushed != 1));
@@ -861,11 +863,14 @@ 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.

		 * Call synchronize_rcu() to wait for the RX path

		 * should it be using the interface and enqueuing

		 * frames at this very time on another CPU.

		 * 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.

		 */

		synchronize_rcu();

		sta_info_flush_cleanup(sdata);



		skb_queue_purge(&sdata->skb_queue);



		/*

net/mac80211/mlme.c

+1 −1
Original line number Diff line number Diff line
@@ -1521,7 +1521,7 @@ static void ieee80211_set_disassoc(struct ieee80211_sub_if_data *sdata, 
	memset(ifmgd->bssid, 0, ETH_ALEN);



	/* remove AP and TDLS peers */

	sta_info_flush(sdata);

	sta_info_flush_defer(sdata);



	/* finally reset all BSS / config parameters */

	changed |= ieee80211_reset_erp_info(sdata);

net/mac80211/sta_info.c

+17 −10
Original line number Diff line number Diff line
@@ -104,6 +104,16 @@ static void cleanup_single_sta(struct sta_info *sta) 
	 * neither mac80211 nor the driver can reference this

	 * sta struct any more except by still existing timers

	 * associated with this station that we clean up below.

	 *

	 * Note though that this still uses the sdata and even

	 * calls the driver in AP and mesh mode, so interfaces

	 * of those types mush use call sta_info_flush_cleanup()

	 * (typically via sta_info_flush()) before deconfiguring

	 * the driver.

	 *

	 * In station mode, nothing happens here so it doesn't

	 * have to (and doesn't) do that, this is intentional to

	 * speed up roaming.

	 */



	if (test_sta_flag(sta, WLAN_STA_PS_STA)) {
@@ -887,14 +897,8 @@ void sta_info_stop(struct ieee80211_local *local) 
	del_timer_sync(&local->sta_cleanup);

}



/**

 * sta_info_flush - flush matching STA entries from the STA table

 *

 * Returns the number of removed STA entries.

 *

 * @sdata: sdata to remove all stations from

 */

int sta_info_flush(struct ieee80211_sub_if_data *sdata)



int sta_info_flush_defer(struct ieee80211_sub_if_data *sdata)

{

	struct ieee80211_local *local = sdata->local;

	struct sta_info *sta, *tmp;
@@ -911,12 +915,15 @@ int sta_info_flush(struct ieee80211_sub_if_data *sdata) 
	}

	mutex_unlock(&local->sta_mtx);



	return ret;

}



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);



	return ret;

}



void ieee80211_sta_expire(struct ieee80211_sub_if_data *sdata,

net/mac80211/sta_info.h

+19 −1
Original line number Diff line number Diff line
@@ -548,7 +548,25 @@ 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(struct ieee80211_sub_if_data *sdata);

int sta_info_flush_defer(struct ieee80211_sub_if_data *sdata);

void sta_info_flush_cleanup(struct ieee80211_sub_if_data *sdata);



/**

 * sta_info_flush - flush matching STA entries from the STA table

 *

 * Returns the number of removed STA entries.

 *

 * @sdata: sdata to remove all stations from

 */

static inline int sta_info_flush(struct ieee80211_sub_if_data *sdata)

{

	int ret = sta_info_flush_defer(sdata);



	sta_info_flush_cleanup(sdata);



	return ret;

}



void sta_set_rate_info_tx(struct sta_info *sta,

			  const struct ieee80211_tx_rate *rate,

			  struct rate_info *rinfo);