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>
diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index 12341ef..1ab7d8e 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -863,12 +863,15 @@
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);