[RFC 07/07] mac80211: Do not call release_buffered_frames if not available.

["Dmitry Tarnyagin" <abi.dmitryt@gmail.com>]

From: Dmitry Tarnyagin <dmitry.tarnyagin@stericsson.com>
Date: Wed, 5 Oct 2011 13:20:04 +0200

A new .release_buffered_frames callback was introduced recently.
Check for the callback presence was missing in the mac80211 code,
and PM state could get broken in some cases.

Signed-off-by: Dmitry Tarnyagin <dmitry.tarnyagin@stericsson.com>
---
  net/mac80211/sta_info.c |    4 +++-
  1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
index 58b1c2b..ff30fe3 100644
--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -1262,7 +1262,9 @@ ieee80211_sta_ps_deliver_response(struct sta_info  
*sta,
  		tids = ieee80211_tids_for_ac(ac);

  		if (!found) {
-			driver_release_tids = sta->driver_buffered_tids & tids;
+			if (local->ops->release_buffered_frames)
+				driver_release_tids =
+					sta->driver_buffered_tids & tids;
  			if (driver_release_tids) {
  				found = true;
  			} else {
-- 
1.7.1