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Date: Thu, 7 Mar 2013 16:08:44 +0800
From: Peter Chen <peter.chen@freescale.com>
To: Maxime Ripard <maxime.ripard@free-electrons.com>
CC: <linux-kernel@vger.kernel.org>, <linux-arm-kernel@lists.infradead.org>,
        <linux-usb@vger.kernel.org>
Subject: Re: v3.9-rc1: swapper/0  [ INFO: possible circular locking
 dependency detected ]
Message-ID: <20130307080843.GG20470@nchen-desktop>
References: <51371B5E.1000508@free-electrons.com>
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On Wed, Mar 06, 2013 at 11:33:02AM +0100, Maxime Ripard wrote:
> Hi,
> 
> Just noticed this in 3.9-rc1 on an iMX28 (ARM) board with a config
> based on mxs_defconfig. I'm using the patchset "Add tested id switch
> and vbus connect detect support for Chipidea" from Peter Chen in its
> 10th version [1], rebased on top of 3.9-rc1, but since this doesn't
> modify the locks present in the udc_irq function, I think the problem
> is elsewhere.
> 
> Please let me know if you have any questions,
> Thanks,
> Maxime
> 
> [1] http://lists.infradead.org/pipermail/linux-arm-kernel/2013-February/151837.html
> 
> 
> [    1.893905] ======================================================
> [    1.900097] [ INFO: possible circular locking dependency detected ]
> [    1.906381] 3.9.0-rc1-00024-g39231ac #475 Not tainted
> [    1.911441] -------------------------------------------------------
> [    1.917716] swapper/0 is trying to acquire lock:
> [    1.922341]  (&(&ci->lock)->rlock){-.....}, at: [<c02580fc>] ep_enable+0x20/0x25c
> [    1.929935] 
> [    1.929935] but task is already holding lock:
> [    1.935782]  (&(&cdev->lock)->rlock){-.....}, at: [<c025e46c>] composite_setup+0x384/0xee8
> [    1.944124] 
> [    1.944124] which lock already depends on the new lock.
> [    1.944124] 
> [    1.952319] 
> [    1.952319] the existing dependency chain (in reverse order) is:
> [    1.959813] 
> -> #1 (&(&cdev->lock)->rlock){-.....}:
> [    1.964829]        [<c005adb0>] lock_acquire+0x98/0x104
> [    1.970106]        [<c0375c28>] _raw_spin_lock_irqsave+0x3c/0x50
> [    1.976152]        [<c025d960>] composite_disconnect+0x1c/0x5c
> [    1.982016]        [<c02591c0>] udc_irq+0x6d8/0xbe8
> [    1.986930]        [<c02571fc>] ci_irq+0x9c/0x108
> [    1.991667]        [<c0067214>] handle_irq_event_percpu+0x5c/0x268
> [    1.997896]        [<c006745c>] handle_irq_event+0x3c/0x5c
> [    2.003417]        [<c00696c0>] handle_level_irq+0x8c/0xe8
> [    2.008933]        [<c0066af4>] generic_handle_irq+0x20/0x30
> [    2.014627]        [<c000fb8c>] handle_IRQ+0x30/0x84
> [    2.019633]        [<c00086f0>] icoll_handle_irq+0x30/0x44
> [    2.025148]        [<c000e8e4>] __irq_svc+0x44/0x54
> [    2.030058]        [<c000fd58>] cpu_idle+0x60/0xec
> [    2.034884]        [<c04e970c>] start_kernel+0x260/0x2a0
> [    2.040237]        [<40008040>] 0x40008040
> [    2.044364] 
> -> #0 (&(&ci->lock)->rlock){-.....}:
> [    2.049210]        [<c005a284>] __lock_acquire+0x14e8/0x1b18
> [    2.054906]        [<c005adb0>] lock_acquire+0x98/0x104
> [    2.060164]        [<c0375c28>] _raw_spin_lock_irqsave+0x3c/0x50
> [    2.066202]        [<c02580fc>] ep_enable+0x20/0x25c
> [    2.071207]        [<c02629d0>] gether_connect+0x34/0x1c0
> [    2.076643]        [<c0262db0>] eem_set_alt+0x70/0xcc
> [    2.081723]        [<c025eb54>] composite_setup+0xa6c/0xee8
> [    2.087325]        [<c0259244>] udc_irq+0x75c/0xbe8
> [    2.092237]        [<c02571fc>] ci_irq+0x9c/0x108
> [    2.096973]        [<c0067214>] handle_irq_event_percpu+0x5c/0x268
> [    2.103194]        [<c006745c>] handle_irq_event+0x3c/0x5c
> [    2.108717]        [<c00696c0>] handle_level_irq+0x8c/0xe8
> [    2.114234]        [<c0066af4>] generic_handle_irq+0x20/0x30
> [    2.119926]        [<c000fb8c>] handle_IRQ+0x30/0x84
> [    2.124929]        [<c00086f0>] icoll_handle_irq+0x30/0x44
> [    2.130445]        [<c000e8e4>] __irq_svc+0x44/0x54
> [    2.135353]        [<c000fd58>] cpu_idle+0x60/0xec
> [    2.140176]        [<c04e970c>] start_kernel+0x260/0x2a0
> [    2.145521]        [<40008040>] 0x40008040
> [    2.149645] 
> [    2.149645] other info that might help us debug this:
> [    2.149645] 
> [    2.157667]  Possible unsafe locking scenario:
> [    2.157667] 
> [    2.163598]        CPU0                    CPU1
> [    2.168134]        ----                    ----
> [    2.172667]   lock(&(&cdev->lock)->rlock);
> [    2.176790]                                lock(&(&ci->lock)->rlock);
> [    2.183255]                                lock(&(&cdev->lock)->rlock);
> [    2.189893]   lock(&(&ci->lock)->rlock);

The precondition of above is the chipidea interrupt can be re-entered.
But as far as I know, the same interrupt can't be re-entered at current
system.


> [    2.193842] 
> [    2.193842]  *** DEADLOCK ***
> [    2.193842] 
> [    2.199782] 1 lock held by swapper/0:
> [    2.203451]  #0:  (&(&cdev->lock)->rlock){-.....}, at: [<c025e46c>] composite_setup+0x384/0xee8
> [    2.212231] 
> [    2.212231] stack backtrace:
> [    2.216663] [<c0014120>] (unwind_backtrace+0x0/0xf0) from [<c0370078>] (print_circular_bug+0x25c/0x2a8)
> [    2.226112] [<c0370078>] (print_circular_bug+0x25c/0x2a8) from [<c005a284>] (__lock_acquire+0x14e8/0x1b18)
> [    2.235813] [<c005a284>] (__lock_acquire+0x14e8/0x1b18) from [<c005adb0>] (lock_acquire+0x98/0x104)
> [    2.244904] [<c005adb0>] (lock_acquire+0x98/0x104) from [<c0375c28>] (_raw_spin_lock_irqsave+0x3c/0x50)
> [    2.254347] [<c0375c28>] (_raw_spin_lock_irqsave+0x3c/0x50) from [<c02580fc>] (ep_enable+0x20/0x25c)
> [    2.263527] [<c02580fc>] (ep_enable+0x20/0x25c) from [<c02629d0>] (gether_connect+0x34/0x1c0)
> [    2.272094] [<c02629d0>] (gether_connect+0x34/0x1c0) from [<c0262db0>] (eem_set_alt+0x70/0xcc)
> [    2.280744] [<c0262db0>] (eem_set_alt+0x70/0xcc) from [<c025eb54>] (composite_setup+0xa6c/0xee8)
> [    2.289572] [<c025eb54>] (composite_setup+0xa6c/0xee8) from [<c0259244>] (udc_irq+0x75c/0xbe8)
> [    2.298226] [<c0259244>] (udc_irq+0x75c/0xbe8) from [<c02571fc>] (ci_irq+0x9c/0x108)
> [    2.306026] [<c02571fc>] (ci_irq+0x9c/0x108) from [<c0067214>] (handle_irq_event_percpu+0x5c/0x268)
> [    2.315119] [<c0067214>] (handle_irq_event_percpu+0x5c/0x268) from [<c006745c>] (handle_irq_event+0x3c/0x5c)
> [    2.324986] [<c006745c>] (handle_irq_event+0x3c/0x5c) from [<c00696c0>] (handle_level_irq+0x8c/0xe8)
> [    2.334159] [<c00696c0>] (handle_level_irq+0x8c/0xe8) from [<c0066af4>] (generic_handle_irq+0x20/0x30)
> [    2.343516] [<c0066af4>] (generic_handle_irq+0x20/0x30) from [<c000fb8c>] (handle_IRQ+0x30/0x84)
> [    2.352342] [<c000fb8c>] (handle_IRQ+0x30/0x84) from [<c00086f0>] (icoll_handle_irq+0x30/0x44)
> [    2.360991] [<c00086f0>] (icoll_handle_irq+0x30/0x44) from [<c000e8e4>] (__irq_svc+0x44/0x54)
> [    2.369531] Exception stack(0xc050df68 to 0xc050dfb0)
> [    2.374612] df60:                   00000001 00000001 00000000 20000013 c050c000 c05476e8
> [    2.382819] df80: c050c000 c050c000 c05476e8 41069265 40504270 00000000 600000d3 c050dfb0
> [    2.391015] dfa0: c005b708 c000fd58 20000013 ffffffff
> [    2.396110] [<c000e8e4>] (__irq_svc+0x44/0x54) from [<c000fd58>] (cpu_idle+0x60/0xec)
> [    2.403990] [<c000fd58>] (cpu_idle+0x60/0xec) from [<c04e970c>] (start_kernel+0x260/0x2a0)
> [    2.412291] [<c04e970c>] (start_kernel+0x260/0x2a0) from [<40008040>] (0x40008040)
> 
> -- 
> Maxime Ripard, Free Electrons
> Kernel, drivers, real-time and embedded Linux
> development, consulting, training and support.
> http://free-electrons.com
> 

-- 

Best Regards,
Peter Chen

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