Backport commit 99b88a0ecbdbc6df03527292571b2b442965814a
The rest is backported in include/linux/compat-2.6.37.h

--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -1124,6 +1124,10 @@ static void __exit ieee80211_exit(void)
 	rc80211_minstrel_ht_exit();
 	rc80211_minstrel_exit();
 
+#if (LINUX_VERSION_CODE < KERNEL_VERSION(2,6,37))
+	flush_scheduled_work();
+#endif
+
 	if (mesh_allocated)
 		ieee80211s_stop();