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Date: Tue, 3 Oct 2006 22:43:09 -0700
From: Greg KH <gregkh@suse.de>
To: Jarek Poplawski <jarkao2@o2.pl>, "Axel C. Voigt" <Axel.Voigt@qosmotec.com>,
       linux-kernel@vger.kernel.org, David Kubicek <dave@awk.cz>
Subject: Re: Problems with hard irq? (inconsistent lock state)
Message-ID: <20061004054309.GA387@suse.de>
References: <46E81D405FFAC240826E54028B3B02953B13@aixlac.qosmotec.com> <20061004054308.GA994@ff.dom.local>
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On Wed, Oct 04, 2006 at 07:43:08AM +0200, Jarek Poplawski wrote:
> On 29-09-2006 13:45, Axel C. Voigt wrote:
> >  
> > Hello all,
> > 
> > today I received the following stack backtrace using debian-2.6.18 with our communications driver accessing a ACM device. This happened when removing (powering off and/or on) the mobile phone (nokia 6630) at /dev/ttyACMx
> > 
> > Are someone able to get a hint for me?
> > 
> > --schnipp--
> > Sep 29 13:29:53 mcs70 kernel:
> > Sep 29 13:29:53 mcs70 kernel: =================================
> > Sep 29 13:29:53 mcs70 kernel: [ INFO: inconsistent lock state ]
> > Sep 29 13:29:53 mcs70 kernel: ---------------------------------
> > Sep 29 13:29:53 mcs70 kernel: inconsistent {hardirq-on-W} -> {in-hardirq-W} usage.
> > Sep 29 13:29:53 mcs70 kernel: startDV24/3864 [HC1[1]:SC0[0]:HE0:SE1] takes:
> > Sep 29 13:29:53 mcs70 kernel: (&acm->read_lock){++..}, at: [<e08952d8>] acm_read_bulk+0x60/0xde [cdc_acm]
> > Sep 29 13:29:53 mcs70 kernel: {hardirq-on-W} state was registered at:
> > Sep 29 13:29:53 mcs70 kernel: [<c01321f3>] lock_acquire+0x56/0x73
> > Sep 29 13:29:53 mcs70 kernel: [<c02ce42a>] _spin_lock+0x1a/0x25
> > Sep 29 13:29:53 mcs70 kernel: [<e08953a8>] acm_rx_tasklet+0x52/0x2be [cdc_acm]
> > Sep 29 13:29:53 mcs70 kernel: [<c011f868>] tasklet_action+0x6d/0xd7
> > Sep 29 13:29:53 mcs70 kernel: [<c011f526>] __do_softirq+0x79/0xf2
> ...
> > Sep 29 13:29:53 mcs70 kernel: stack backtrace:
> > Sep 29 13:29:53 mcs70 kernel: [<c010376e>] show_trace+0x16/0x18
> > Sep 29 13:29:53 mcs70 kernel: [<c010383c>] dump_stack+0x19/0x1b
> > Sep 29 13:29:53 mcs70 kernel: [<c0130ad8>] print_usage_bug+0x1e1/0x1eb
> > Sep 29 13:29:53 mcs70 kernel: [<c0130b86>] mark_lock+0xa4/0x4d9
> > Sep 29 13:29:53 mcs70 kernel: [<c0131823>] __lock_acquire+0x41a/0x841
> > Sep 29 13:29:53 mcs70 kernel: [<c01321f3>] lock_acquire+0x56/0x73
> > Sep 29 13:29:53 mcs70 kernel: [<c02ce42a>] _spin_lock+0x1a/0x25
> > Sep 29 13:29:53 mcs70 kernel: [<e08952d8>] acm_read_bulk+0x60/0xde [cdc_acm]
> ...
> > Sep 29 13:29:53 mcs70 kernel: [<c0104b26>] do_IRQ+0x4e/0x5f
> > Sep 29 13:29:53 mcs70 kernel: [<c0103339>] common_interrupt+0x25/0x2c
> ... 
> 
> It looks in drivers/usb/class/cdc-acm.c acm_rx_tasklet could be preempted
> with acm->read_lock by acm_read_bulk which uses the same lock from hardirq
> context.
> 
> So probably spin_lock_irqsave is needed.  

Yup.  Care to send a patch?

thanks,

greg k-h