mac80211: allow drivers to sleep in ampdu_action

Allow drivers to sleep, and indicate this in
the documentation. ath9k has some locking I
don't understand, so keep it safe and disable
BHs in it, all other drivers look fine with
the context change.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 7f9401b..bbae3d9 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -1640,7 +1640,7 @@
  * 	is the first frame we expect to perform the action on. Notice
  * 	that TX/RX_STOP can pass NULL for this parameter.
  *	Returns a negative error code on failure.
- *	The callback must be atomic.
+ *	The callback can sleep.
  *
  * @get_survey: Return per-channel survey information
  *