• Johannes Berg's avatar
    mac80211: fix station wakeup powersave race · e3685e03
    Johannes Berg authored
    Consider the following (relatively unlikely) scenario:
     1) station goes to sleep while frames are buffered in driver
     2) driver blocks wakeup (until no more frames are buffered)
     3) station wakes up again
     4) driver unblocks wakeup
    
    In this case, the current mac80211 code will do the following:
     1) WLAN_STA_PS_STA set
     2) WLAN_STA_PS_DRIVER set
     3) - nothing -
     4) WLAN_STA_PS_DRIVER cleared
    
    As a result, no frames will be delivered to the client, even
    though it is awake, until it sends another frame to us that
    triggers ieee80211_sta_ps_deliver_wakeup() in sta_ps_end().
    
    Since we now take the PS spinlock, we can fix this while at
    the same time removing the complexity with the pending skb
    queue function. This was broken since my commit 50a9432d
    ("mac80211: fix powersaving clients races") due to removing
    the clearing of WLAN_STA_PS_STA in the RX path.
    
    While at it, fix a cleanup path issue when a station is
    removed while the driver is still blocking its wakeup.
    Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
    e3685e03
util.c 70.9 KB