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Message-ID: <4A91F100.9040804@lwfinger.net>
Date: Sun, 23 Aug 2009 20:46:40 -0500
From: Larry Finger <Larry.Finger@lwfinger.net>
MIME-Version: 1.0
To: Herton Ronaldo Krzesinski <herton@mandriva.com.br>
CC: linux-wireless@vger.kernel.org,
	Hin-Tak Leung <htl10@users.sourceforge.net>
Subject: Re: [RFC/RFT] rtl8187: Implement rfkill support
References: <200908220038.35564.herton@mandriva.com.br>
In-Reply-To: <200908220038.35564.herton@mandriva.com.br>
Content-Type: text/plain; charset=ISO-8859-1
Sender: linux-wireless-owner@vger.kernel.org
List-ID: <linux-wireless.vger.kernel.org>

Herton Ronaldo Krzesinski wrote:
> This change implements rfkill support for RTL8187B and RTL8187L devices,
> using new cfg80211 rfkill API.
> 
> Signed-off-by: Herton Ronaldo Krzesinski <herton@mandriva.com.br>
> ---

I found a problem with this patch. When I issue an 'rfkill block 1'
command, I get the following circular locking warning:


=======================================================
[ INFO: possible circular locking dependency detected ]
2.6.31-rc6-wl #201
-------------------------------------------------------
rfkill/30578 is trying to acquire lock:
 (&(&priv->work)->work#2){+.+...}, at: [<ffffffff81051215>]
__cancel_work_timer+0xd9/0x222

but task is already holding lock:
 (&priv->conf_mutex#2){+.+.+.}, at: [<ffffffffa064a024>]
rtl8187_stop+0x31/0x364 [rtl8187]

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&priv->conf_mutex#2){+.+.+.}:
       [<ffffffff81065957>] __lock_acquire+0x12d0/0x1614
       [<ffffffff81065d54>] lock_acquire+0xb9/0xdd
       [<ffffffff8127c32f>] mutex_lock_nested+0x56/0x2a8
       [<ffffffffa064a392>] rtl8187_work+0x3b/0xf2 [rtl8187]
       [<ffffffff81050758>] worker_thread+0x1fa/0x30a
       [<ffffffff81054ca5>] kthread+0x8f/0x97
       [<ffffffff8100cb7a>] child_rip+0xa/0x20
       [<ffffffffffffffff>] 0xffffffffffffffff

-> #0 (&(&priv->work)->work#2){+.+...}:
       [<ffffffff8106568c>] __lock_acquire+0x1005/0x1614
       [<ffffffff81065d54>] lock_acquire+0xb9/0xdd
       [<ffffffff8105124e>] __cancel_work_timer+0x112/0x222
       [<ffffffff8105136b>] cancel_delayed_work_sync+0xd/0xf
       [<ffffffffa064a33f>] rtl8187_stop+0x34c/0x364 [rtl8187]
       [<ffffffffa0242866>] ieee80211_stop_device+0x29/0x61 [mac80211]
       [<ffffffffa0239194>] ieee80211_stop+0x476/0x530 [mac80211]
       [<ffffffff8120ce15>] dev_close+0x8a/0xac
       [<ffffffffa01d9fa7>] cfg80211_rfkill_set_block+0x4a/0x7a [cfg80211]
       [<ffffffffa01bf4f0>] rfkill_set_block+0x84/0xd9 [rfkill]
       [<ffffffffa01bfc31>] rfkill_fop_write+0xda/0x124 [rfkill]
       [<ffffffff810cf286>] vfs_write+0xae/0x14a
       [<ffffffff810cf3e6>] sys_write+0x47/0x6e
       [<ffffffff8100ba6b>] system_call_fastpath+0x16/0x1b
       [<ffffffffffffffff>] 0xffffffffffffffff

other info that might help us debug this:

4 locks held by rfkill/30578:
 #0:  (rfkill_global_mutex){+.+.+.}, at: [<ffffffffa01bfbbc>]
rfkill_fop_write+0x65/0x124 [rfkill]
 #1:  (rtnl_mutex){+.+.+.}, at: [<ffffffff81215a60>] rtnl_lock+0x12/0x14
 #2:  (&rdev->devlist_mtx){+.+.+.}, at: [<ffffffffa01d9f89>]
cfg80211_rfkill_set_block+0x2c/0x7a [cfg80211]
 #3:  (&priv->conf_mutex#2){+.+.+.}, at: [<ffffffffa064a024>]
rtl8187_stop+0x31/0x364 [rtl8187]

stack backtrace:
Pid: 30578, comm: rfkill Not tainted 2.6.31-rc6-wl #201
Call Trace:
 [<ffffffff810641ec>] print_circular_bug_tail+0xc1/0xcc
 [<ffffffff8106568c>] __lock_acquire+0x1005/0x1614
 [<ffffffff81065d54>] lock_acquire+0xb9/0xdd
 [<ffffffff81051215>] ? __cancel_work_timer+0xd9/0x222
 [<ffffffff8105124e>] __cancel_work_timer+0x112/0x222
 [<ffffffff81051215>] ? __cancel_work_timer+0xd9/0x222
 [<ffffffff81063791>] ? mark_held_locks+0x4d/0x6b
 [<ffffffff8127db94>] ? _spin_unlock_irq+0x2b/0x30
 [<ffffffff81063a04>] ? trace_hardirqs_on_caller+0x10b/0x12f
 [<ffffffff81063a35>] ? trace_hardirqs_on+0xd/0xf
 [<ffffffff8127db94>] ? _spin_unlock_irq+0x2b/0x30
 [<ffffffffa00de2c4>] ? usb_kill_anchored_urbs+0x46/0x5c [usbcore]
 [<ffffffff8105136b>] cancel_delayed_work_sync+0xd/0xf
 [<ffffffffa064a33f>] rtl8187_stop+0x34c/0x364 [rtl8187]
 [<ffffffffa0242866>] ieee80211_stop_device+0x29/0x61 [mac80211]
 [<ffffffffa0239194>] ieee80211_stop+0x476/0x530 [mac80211]
 [<ffffffffa0238d68>] ? ieee80211_stop+0x4a/0x530 [mac80211]
 [<ffffffff81044a28>] ? local_bh_enable_ip+0xc8/0xcd
 [<ffffffff8127db65>] ? _spin_unlock_bh+0x2f/0x33
 [<ffffffff8121d116>] ? dev_deactivate+0x162/0x192
 [<ffffffff8120ce15>] dev_close+0x8a/0xac
 [<ffffffffa01d9fa7>] cfg80211_rfkill_set_block+0x4a/0x7a [cfg80211]
 [<ffffffffa01bf4f0>] rfkill_set_block+0x84/0xd9 [rfkill]
 [<ffffffffa01bfc31>] rfkill_fop_write+0xda/0x124 [rfkill]
 [<ffffffff8100ba9c>] ? sysret_check+0x27/0x62
 [<ffffffff810cf286>] vfs_write+0xae/0x14a
 [<ffffffff810cf3e6>] sys_write+0x47/0x6e
 [<ffffffff8100ba6b>] system_call_fastpath+0x16/0x1bf


Larry