From: Johannes Berg <johannes.berg@xxxxxxxxx>
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@xxxxxxxxx>
---
net/mac80211/cfg.c | 8 ++++++--
net/mac80211/iface.c | 13 ++++++++-----
net/mac80211/sta_info.c | 2 --
net/mac80211/sta_info.h | 14 ++++++++++++++
4 files changed, 28 insertions(+), 9 deletions(-)
diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index 8576723..c485b36 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -1014,8 +1014,12 @@ 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);
sdata->vif.bss_conf.enable_beacon = false;
clear_bit(SDATA_STATE_OFFCHANNEL_BEACON_STOPPED, &sdata->state);
diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index dcf943e..e02f7a0 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -872,12 +872,15 @@ 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);
diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
index 2f74031..f61bb46 100644
--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -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);
}
diff --git a/net/mac80211/sta_info.h b/net/mac80211/sta_info.h
index c3266aed..031e4a5 100644
--- a/net/mac80211/sta_info.h
+++ b/net/mac80211/sta_info.h
@@ -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;
--
1.8.0
--
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