• Juuso Oikarinen's avatar
    mac80211: Fix circular locking dependency in ARP filter handling · 68542962
    Juuso Oikarinen authored
    There is a circular locking dependency when configuring the
    hardware ARP filters on association, occurring when flushing the mac80211
    workqueue. This is what happens:
    
    [   92.026800] =======================================================
    [   92.030507] [ INFO: possible circular locking dependency detected ]
    [   92.030507] 2.6.34-04781-g2b2c009e #85
    [   92.030507] -------------------------------------------------------
    [   92.030507] modprobe/5225 is trying to acquire lock:
    [   92.030507]  ((wiphy_name(local->hw.wiphy))){+.+.+.}, at: [<ffffffff8105b5c0>] flush_workq
    ueue+0x0/0xb0
    [   92.030507]
    [   92.030507] but task is already holding lock:
    [   92.030507]  (rtnl_mutex){+.+.+.}, at: [<ffffffff812b9ce2>] rtnl_lock+0x12/0x20
    [   92.030507]
    [   92.030507] which lock already depends on the new lock.
    [   92.030507]
    [   92.030507]
    [   92.030507] the existing dependency chain (in reverse order) is:
    [   92.030507]
    [   92.030507] -> #2 (rtnl_mutex){+.+.+.}:
    [   92.030507]        [<ffffffff810761fb>] lock_acquire+0xdb/0x110
    [   92.030507]        [<ffffffff81341754>] mutex_lock_nested+0x44/0x300
    [   92.030507]        [<ffffffff812b9ce2>] rtnl_lock+0x12/0x20
    [   92.030507]        [<ffffffffa022d47c>] ieee80211_assoc_done+0x6c/0xe0 [mac80211]
    [   92.030507]        [<ffffffffa022f2ad>] ieee80211_work_work+0x31d/0x1280 [mac80211]
    
    [   92.030507] -> #1 ((&local->work_work)){+.+.+.}:
    [   92.030507]        [<ffffffff810761fb>] lock_acquire+0xdb/0x110
    [   92.030507]        [<ffffffff8105a51a>] worker_thread+0x22a/0x370
    [   92.030507]        [<ffffffff8105ecc6>] kthread+0x96/0xb0
    [   92.030507]        [<ffffffff81003a94>] kernel_thread_helper+0x4/0x10
    [   92.030507]
    [   92.030507] -> #0 ((wiphy_name(local->hw.wiphy))){+.+.+.}:
    [   92.030507]        [<ffffffff81075fdc>] __lock_acquire+0x1c0c/0x1d50
    [   92.030507]        [<ffffffff810761fb>] lock_acquire+0xdb/0x110
    [   92.030507]        [<ffffffff8105b60e>] flush_workqueue+0x4e/0xb0
    [   92.030507]        [<ffffffffa023ff7b>] ieee80211_stop_device+0x2b/0xb0 [mac80211]
    [   92.030507]        [<ffffffffa0231635>] ieee80211_stop+0x3e5/0x680 [mac80211]
    
    The locking in this case is quite complex. Fix the problem by rewriting the
    way the hardware ARP filter list is handled - i.e. make a copy of the address
    list to the bss_conf struct, and provide that list to the hardware driver
    when needed.
    
    The current patch will enable filtering also in promiscuous mode. This may need
    to be changed in the future.
    Reported-by: default avatarReinette Chatre <reinette.chatre@intel.com>
    Signed-off-by: default avatarJuuso Oikarinen <juuso.oikarinen@nokia.com>
    Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
    68542962
main.c 20.9 KB