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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: Johannes Berg <johannes.berg@intel.com>
This commit is contained in:
Johannes Berg 2012-12-14 14:56:03 +01:00
parent 361c9c8b0e
commit 75de9113bb
4 changed files with 29 additions and 9 deletions
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9
net/mac80211/cfg.c
View File

@ -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);

13
net/mac80211/iface.c
View File

@ -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);

2
net/mac80211/sta_info.c
View File

@ -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);
}

14
net/mac80211/sta_info.h
View File

@ -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;