On Monday 27 December 2010 02:10:05 Bob Copeland wrote:
> ath5k_reset is called from process context and takes the cc_lock
> with plain spin_lock(), but cc_lock can also be taken from tasklets
> in softirq context. Thus we need to at least use spin_lock_bh.
>
> This fixes the following lockdep warning:
>
> [ 19.967874] sky2 0000:01:00.0: eth0: enabling interface
> [ 19.982761] ieee80211 phy0: device now idle
> [ 20.904809] NET: Registered protocol family 17
> [ 21.243857] ieee80211 phy0: device no longer idle - scanning
> [ 21.404343]
> [ 21.404346] =================================
> [ 21.404450] [ INFO: inconsistent lock state ]
> [ 21.404518] 2.6.37-rc7-wl+ #242
> [ 21.404582] ---------------------------------
> [ 21.404650] inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
> [ 21.404721] kworker/u:4/982 [HC0[0]:SC1[3]:HE1:SE0] takes:
> [ 21.404792] (&(&common->cc_lock)->rlock){+.?...}, at: [<f8115780>]
> ath5k_ani_calibration+0x29/0x5d9 [ath5k] [ 21.405011] {SOFTIRQ-ON-W}
> state was registered at:
> [ 21.405011] [<c105cadd>] __lock_acquire+0x62f/0x13c1
> [ 21.405011] [<c105d944>] lock_acquire+0xd5/0xf1
> [ 21.405011] [<c12c978d>] _raw_spin_lock+0x45/0x72
> [ 21.405011] [<f8111533>] ath5k_reset+0x2c0/0x349 [ath5k]
> [ 21.405011] [<f8111a7a>] ath5k_start+0xb8/0x139 [ath5k]
> [ 21.405011] [<f849c714>] ieee80211_do_open+0x13f/0x819 [mac80211]
> [ 21.405011] [<f849ce51>] ieee80211_open+0x63/0x66 [mac80211]
> [ 21.405011] [<c1258b2e>] __dev_open+0x8d/0xb6
> [ 21.405011] [<c1255c64>] __dev_change_flags+0x9d/0x114
> [ 21.405011] [<c1258a75>] dev_change_flags+0x18/0x44
> [ 21.405011] [<c1262990>] do_setlink+0x23f/0x521
> [ 21.405011] [<c1262d58>] rtnl_setlink+0xe6/0xea
> [ 21.405011] [<c126347c>] rtnetlink_rcv_msg+0x18a/0x1a0
> [ 21.405011] [<c126d5f0>] netlink_rcv_skb+0x35/0x7b
> [ 21.405011] [<c12632eb>] rtnetlink_rcv+0x20/0x27
> [ 21.405011] [<c126d370>] netlink_unicast+0x1bb/0x21e
> [ 21.405011] [<c126db21>] netlink_sendmsg+0x23b/0x288
> [ 21.405011] [<c124823c>] sock_sendmsg+0xac/0xc4
> [ 21.405011] [<c1248680>] sys_sendmsg+0x152/0x1a2
> [ 21.405011] [<c1249b0d>] sys_socketcall+0x214/0x275
> [ 21.405011] [<c10029d0>] sysenter_do_call+0x12/0x36
> [ 21.405011] irq event stamp: 138032
> [ 21.405011] hardirqs last enabled at (138032): [<c12ca252>]
> _raw_spin_unlock_irqrestore+0x3b/0x5e [ 21.405011] hardirqs last
> disabled at (138031): [<c12c98cc>] _raw_spin_lock_irqsave+0x18/0x7e [
> 21.405011] softirqs last enabled at (138024): [<f84a570e>]
> ieee80211_tx_skb+0x47/0x49 [mac80211] [ 21.405011] softirqs last
> disabled at (138027): [<c100452b>] do_softirq+0x63/0xb4 [ 21.405011]
> [ 21.405011] other info that might help us debug this:
> [ 21.405011] 3 locks held by kworker/u:4/982:
> [ 21.405011] #0: (name){+.+.+.}, at: [<c1046158>]
> process_one_work+0x1b8/0x41b [ 21.405011] #1:
> ((&(&local->scan_work)->work)){+.+.+.}, at: [<c1046158>]
> process_one_work+0x1b8/0x41b [ 21.405011] #2: (&local->mtx){+.+.+.},
> at: [<f84920fb>] ieee80211_scan_work+0x32/0x4a4 [mac80211] [ 21.405011]
> [ 21.405011] stack backtrace:
> [ 21.405011] Pid: 982, comm: kworker/u:4 Not tainted 2.6.37-rc7-wl+ #242
> [ 21.405011] Call Trace:
> [ 21.405011] [<c12c6e68>] ? printk+0x1d/0x25
> [ 21.405011] [<c105a742>] print_usage_bug+0x181/0x18b
> [ 21.405011] [<c105b196>] ? check_usage_forwards+0x0/0xb6
> [ 21.405011] [<c105a9ec>] mark_lock+0x2a0/0x4aa
> [ 21.405011] [<c1059f6d>] ? trace_hardirqs_off+0xb/0xd
> [ 21.405011] [<c105ca68>] __lock_acquire+0x5ba/0x13c1
> [ 21.405011] [<c1059eed>] ? trace_hardirqs_off_caller+0x18/0x8d
> [ 21.405011] [<c1059f6d>] ? trace_hardirqs_off+0xb/0xd
> [ 21.405011] [<c1050411>] ? local_clock+0x2c/0x4f
> [ 21.405011] [<c1059e00>] ? save_trace+0x2/0xa0
> [ 21.405011] [<c105ac39>] ? mark_held_locks+0x43/0x5b
> [ 21.405011] [<c12ca252>] ? _raw_spin_unlock_irqrestore+0x3b/0x5e
> [ 21.405011] [<f8115780>] ? ath5k_ani_calibration+0x29/0x5d9 [ath5k]
> [ 21.405011] [<c105d944>] lock_acquire+0xd5/0xf1
> [ 21.405011] [<f8115780>] ? ath5k_ani_calibration+0x29/0x5d9 [ath5k]
> [ 21.405011] [<c12c9b1a>] _raw_spin_lock_bh+0x4a/0x77
> [ 21.405011] [<f8115780>] ? ath5k_ani_calibration+0x29/0x5d9 [ath5k]
> [ 21.405011] [<f8115780>] ath5k_ani_calibration+0x29/0x5d9 [ath5k]
> [ 21.405011] [<c105ac39>] ? mark_held_locks+0x43/0x5b
> [ 21.405011] [<f8113496>] ath5k_tasklet_ani+0x1d/0x27 [ath5k]
> [ 21.405011] [<c1037304>] tasklet_action+0x96/0x137
> [ 21.405011] [<c10379b5>] __do_softirq+0xde/0x1c3
> [ 21.405011] [<c10b0cef>] ? arch_get_unmapped_area_topdown+0x3b/0x127
> [ 21.405011] [<c10378d7>] ? __do_softirq+0x0/0x1c3
> [ 21.405011] <IRQ> [<c1036dee>] ? irq_exit+0x3d/0x49
> [ 21.405011] [<c1003b4f>] ? do_IRQ+0x98/0xac
> [ 21.405011] [<c1002eee>] ? common_interrupt+0x2e/0x34
> [ 21.405011] [<c103007b>] ? sys_unshare+0x57/0x226
> [ 21.405011] [<c1047fee>] ? queue_delayed_work+0x1/0x27
> [ 21.405011] [<f84a83a0>] ? ieee80211_queue_delayed_work+0x2e/0x33
> [mac80211] [ 21.405011] [<f8492528>] ? ieee80211_scan_work+0x45f/0x4a4
> [mac80211] [ 21.405011] [<c104620e>] ? process_one_work+0x26e/0x41b
> [ 21.405011] [<c1046158>] ? process_one_work+0x1b8/0x41b
> [ 21.405011] [<f84920c9>] ? ieee80211_scan_work+0x0/0x4a4 [mac80211]
> [ 21.405011] [<c10466b6>] ? worker_thread+0x18a/0x2a5
> [ 21.405011] [<c12ca25e>] ? _raw_spin_unlock_irqrestore+0x47/0x5e
> [ 21.405011] [<c104652c>] ? worker_thread+0x0/0x2a5
> [ 21.405011] [<c104abe7>] ? kthread+0x67/0x6c
> [ 21.405011] [<c104ab80>] ? kthread+0x0/0x6c
> [ 21.405011] [<c1002efa>] ? kernel_thread_helper+0x6/0x10
>
> Signed-off-by: Bob Copeland <me@xxxxxxxxxxxxxxx>
> ---
> drivers/net/wireless/ath/ath5k/base.c | 4 ++--
> 1 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/wireless/ath/ath5k/base.c
> b/drivers/net/wireless/ath/ath5k/base.c index e4ec40c..63ef7ff 100644
> --- a/drivers/net/wireless/ath/ath5k/base.c
> +++ b/drivers/net/wireless/ath/ath5k/base.c
> @@ -2703,11 +2703,11 @@ ath5k_reset(struct ath5k_softc *sc, struct
> ieee80211_channel *chan,
>
> /* clear survey data and cycle counters */
> memset(&sc->survey, 0, sizeof(sc->survey));
> - spin_lock(&common->cc_lock);
> + spin_lock_bh(&common->cc_lock);
> ath_hw_cycle_counters_update(common);
> memset(&common->cc_survey, 0, sizeof(common->cc_survey));
> memset(&common->cc_ani, 0, sizeof(common->cc_ani));
> - spin_unlock(&common->cc_lock);
> + spin_unlock_bh(&common->cc_lock);
>
> /*
> * Change channels and update the h/w rate map if we're switching;
Acked-by: Bruno Randolf <br1@xxxxxxxxxxx>
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