[PATCH 4.9 11/51] mac80211: fix power saving clients handling in iwlwifi

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Emmanuel Grumbach <emmanuel.grumbach@xxxxxxxxx>


[ Upstream commit d98937f4ea713d21e0fcc345919f86c877dd8d6f ]

iwlwifi now supports RSS and can't let mac80211 track the
PS state based on the Rx frames since they can come out of
order. iwlwifi is now advertising AP_LINK_PS, and uses
explicit notifications to teach mac80211 about the PS state
of the stations and the PS poll / uAPSD trigger frames
coming our way from the peers.

Because of that, the TIM stopped being maintained in
mac80211. I tried to fix this in commit c68df2e7be0c
("mac80211: allow using AP_LINK_PS with mac80211-generated TIM IE")
but that was later reverted by Felix in commit 6c18a6b4e799
("Revert "mac80211: allow using AP_LINK_PS with mac80211-generated TIM IE")
since it broke drivers that do not implement set_tim.

Since none of the drivers that set AP_LINK_PS have the
set_tim() handler set besides iwlwifi, I can bail out in
__sta_info_recalc_tim if AP_LINK_PS AND .set_tim is not
implemented.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@xxxxxxxxx>
Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 net/mac80211/sta_info.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -688,7 +688,7 @@ static void __sta_info_recalc_tim(struct
 	}
 
 	/* No need to do anything if the driver does all */
-	if (ieee80211_hw_check(&local->hw, AP_LINK_PS))
+	if (ieee80211_hw_check(&local->hw, AP_LINK_PS) && !local->ops->set_tim)
 		return;
 
 	if (sta->dead)