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Date: Sat, 5 Feb 2011 15:11:12 -0500 (EST)
From: Alan Stern <stern@rowland.harvard.edu>
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To: Minchan Kim <minchan.kim@gmail.com>, "Rafael J. Wysocki" <rjw@sisk.pl>
cc: linux kernel mailing list <linux-kernel@vger.kernel.org>,
        Greg Kroah-Hartman <gregkh@suse.de>,
        Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [BUG] usb_set_device_state
In-Reply-To: <20110205171504.GA1044@barrios-desktop>
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On Sun, 6 Feb 2011, Minchan Kim wrote:

> I got following message during booting mmotm-02-04.
> 
> sky2 0000:04:00.0: PCI INT A -> GSI 16 (level, low) -> IRQ 16
> sky2 0000:04:00.0: setting latency timer to 64
> sky2 0000:04:00.0: Yukon-2 EC Ultra chip revision 2
> sky2 0000:04:00.0: irq 44 for MSI/MSI-X
> sky2 0000:04:00.0: eth0: addr 00:1a:4d:65:01:51
> BUG: sleeping function called from invalid context at kernel/mutex.c:278
> in_atomic(): 0, irqs_disabled(): 1, pid: 21, name: khubd
> 3 locks held by khubd/21:
>  #0:  (&__lockdep_no_validate__){+.+.+.}, at: [<c047e2dd>] hub_thread+0xcd/0xf10
>  #1:  (&__lockdep_no_validate__){+.+.+.}, at: [<c0419a82>] device_attach+0x22/0x90
>  #2:  (device_state_lock){......}, at: [<c047c4c4>] usb_set_device_state+0x24/0xf0
> irq event stamp: 6264
> hardirqs last  enabled at (6263): [<c05d7adf>] __mutex_unlock_slowpath+0xaf/0x140
> hardirqs last disabled at (6264): [<c05d9196>] _raw_spin_lock_irqsave+0x26/0x70
> softirqs last  enabled at (6252): [<c015d137>] del_timer_sync+0x57/0xa0
> softirqs last disabled at (6250): [<c015d0f4>] del_timer_sync+0x14/0xa0
> Pid: 21, comm: khubd Not tainted 2.6.38-rc3-mm1+ #1
> Call Trace:
>  [<c015d0f4>] ? del_timer_sync+0x14/0xa0
>  [<c013cc29>] ? __might_sleep+0xe9/0x120
>  [<c05d80f6>] ? mutex_lock_nested+0x26/0x50
>  [<c038272f>] ? do_raw_spin_lock+0x3f/0x140
>  [<c0289b98>] ? sysfs_get_dirent+0x28/0x70
>  [<c028b3f1>] ? sysfs_merge_group+0x21/0xc0
>  [<c041dd75>] ? wakeup_sysfs_add+0x15/0x20
>  [<c041fdf5>] ? device_set_wakeup_capable+0x45/0x80
>  [<c047c578>] ? usb_set_device_state+0xd8/0xf0
>  [<c0484556>] ? usb_set_configuration+0x366/0x680
>  [<c028a381>] ? sysfs_do_create_link+0xb1/0x1e0
>  [<c048c93b>] ? generic_probe+0x3b/0x90
>  [<c028a4e7>] ? sysfs_create_link+0x17/0x20
>  [<c0485849>] ? usb_probe_device+0x29/0x50
>  [<c0419822>] ? driver_probe_device+0x82/0x190
>  [<c05d98a2>] ? _raw_spin_unlock+0x22/0x30
>  [<c0419a09>] ? __device_attach+0x49/0x60
>  [<c0418af3>] ? bus_for_each_drv+0x53/0x80
>  [<c0419ada>] ? device_attach+0x7a/0x90
>  [<c04199c0>] ? __device_attach+0x0/0x60
>  [<c0418915>] ? bus_probe_device+0x25/0x40
>  [<c04174c5>] ? device_add+0x5a5/0x670
>  [<c047c100>] ? usb_hub_init+0xa0/0xb0
>  [<c042182c>] ? pm_runtime_forbid+0x4c/0x60
>  [<c047dee0>] ? usb_new_device+0xe0/0x120
>  [<c018336b>] ? trace_hardirqs_on+0xb/0x10
>  [<c047e904>] ? hub_thread+0x6f4/0xf10
>  [<c016d7a0>] ? autoremove_wake_function+0x0/0x50
>  [<c047e210>] ? hub_thread+0x0/0xf10
>  [<c016d384>] ? kthread+0x84/0x90
>  [<c016d300>] ? kthread+0x0/0x90
>  [<c0103606>] ? kernel_thread_helper+0x6/0x10
> -
> 
> It seems usb_set_device_state disable irq by spin_lock_irqsave.
> But it calls device_set_wakeup_capable which ends up calling sysfs_merge_group.
> It calls mutex_lock. :(
> 
> Is it already known BUG?

No, it was newly introduced by changes to the 
device_set_wakeup_capable() routine.  Rafael, this sort of problem may 
occur in other places too, since previously there was no requirement 
that device_set_wakeup_capable() be called in process context.

Alan Stern

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