mac80211: merge a fix for a ps-poll handling issue

Signed-off-by: Felix Fietkau <nbd@openwrt.org>

SVN-Revision: 47958

package/kernel/mac80211/patches/304-mac80211-fix-PS-Poll-handling.patch

@@ -0,0 +1,48 @@
+From: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
+Date: Sun, 20 Dec 2015 13:50:00 +0200
+Subject: [PATCH] mac80211: fix PS-Poll handling
+
+My commit below broken PS-Poll handling. In case the driver
+has no frames buffered, driver_release_tids will be 0, but
+calling find_highest_prio_tid() with 0 as a parameter is
+not a good idea:
+fls(0) - 1 = -1.
+This bug caused mac80211 to think that frames were buffered
+in the driver which in turn was confused because mac80211
+was asking to release frames that were not reported to
+exist.
+On iwlwifi, this led to the WARNING below:
+
+WARNING: CPU: 0 PID: 11230 at drivers/net/wireless/intel/iwlwifi/mvm/sta.c:1733 iwl_mvm_sta_modify_sleep_tx_count+0x2af/0x320 [iwlmvm]()
+ffffffffc0627c60 ffff8800069b7648 ffffffff81888913 0000000000000000
+0000000000000000 ffff8800069b7688 ffffffff81089d6a ffff8800069b7678
+0000000000000001 ffff88003b35abf0 ffff88000698b128 ffff8800069b76d4
+Call Trace:
+[<ffffffff81888913>] dump_stack+0x4c/0x65
+[<ffffffff81089d6a>] warn_slowpath_common+0x8a/0xc0
+[<ffffffff81089e5a>] warn_slowpath_null+0x1a/0x20
+[<ffffffffc05f36bf>] iwl_mvm_sta_modify_sleep_tx_count+0x2af/0x320 [iwlmvm]
+[<ffffffffc05dae41>] iwl_mvm_mac_release_buffered_frames+0x31/0x40 [iwlmvm]
+[<ffffffffc045d8b6>] ieee80211_sta_ps_deliver_response+0x6e6/0xd80 [mac80211]
+[<ffffffffc0461296>] ieee80211_sta_ps_deliver_poll_response+0x26/0x30 [mac80211]
+[<ffffffffc048f743>] ieee80211_rx_handlers+0xa83/0x2900 [mac80211]
+[<ffffffffc04917ad>] ieee80211_prepare_and_rx_handle+0x1ed/0xa70 [mac80211]
+[<ffffffffc045e3d5>] ? sta_info_get_bss+0x5/0x4a0 [mac80211]
+[<ffffffffc04925b6>] ieee80211_rx_napi+0x586/0xcd0 [mac80211]
+[<ffffffffc05eaa3e>] iwl_mvm_rx_rx_mpdu+0x59e/0xc60 [iwlmvm]
+
+Fixes: 0ead2510f8ce ("mac80211: allow the driver to send EOSP when needed")
+Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
+---
+
+--- a/net/mac80211/sta_info.c
++++ b/net/mac80211/sta_info.c
+@@ -1453,7 +1453,7 @@ ieee80211_sta_ps_deliver_response(struct
+ 
+ 	more_data = ieee80211_sta_ps_more_data(sta, ignored_acs, reason, driver_release_tids);
+ 
+-	if (reason == IEEE80211_FRAME_RELEASE_PSPOLL)
++	if (driver_release_tids && reason == IEEE80211_FRAME_RELEASE_PSPOLL)
+ 		driver_release_tids =
+ 			BIT(find_highest_prio_tid(driver_release_tids));
+