mac80211: serialize rx path workers

This patch addresses the issue of serialization between
the main rx path and various reorder release timers.

<http://www.spinics.net/lists/linux-wireless/msg57214.html>

It converts the previously local "frames" queue into
a global rx queue [rx_skb_queue]. This way, everyone
(be it the main rx-path or some reorder release timeout)
can add frames to it.

Only one active rx handler worker [ieee80211_rx_handlers]
is needed. All other threads which have lost the race of
"runnning_rx_handler" can now simply "return", knowing that
the thread who had the "edge" will also take care of their
workload.

Signed-off-by: Christian Lamparter <chunkeey@googlemail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index a9eb67380da6..1bf2fc8b9bde 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -761,6 +761,15 @@ struct ieee80211_local {
         struct sk_buff_head skb_queue;
         struct sk_buff_head skb_queue_unreliable;
 
+        /*
+         * Internal FIFO queue which is shared between multiple rx path
+         * stages. Its main task is to provide a serialization mechanism,
+         * so all rx handlers can enjoy having exclusive access to their
+         * private data structures.
+         */
+        struct sk_buff_head rx_skb_queue;
+        bool running_rx_handler;        /* protected by rx_skb_queue.lock */
+
         /* Station data */
         /*
          * The mutex only protects the list and counter,