linux-kernel - Re: sleeping while atomic in dwc3_gadget

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Message-ID: <20130701121659.GE28300@arwen.pp.htv.fi>
Date:	Mon, 1 Jul 2013 15:16:59 +0300
From:	Felipe Balbi <balbi@...com>
To:	Stephen Boyd <sboyd@...eaurora.org>
CC:	<balbi@...com>, Vivek Gautam <gautam.vivek@...sung.com>,
	<linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: sleeping while atomic in dwc3_gadget_start

On Fri, Jun 28, 2013 at 07:02:32PM -0700, Stephen Boyd wrote:
> On 06/28/13 03:58, Felipe Balbi wrote:
> > Hi,
> >
> > On Thu, Jun 27, 2013 at 09:57:52AM -0700, Stephen Boyd wrote:
> >> On 06/26/13 23:58, Felipe Balbi wrote:
> >>> On Wed, Jun 26, 2013 at 02:52:56PM -0700, Stephen Boyd wrote:
> >>>> Hi,
> >>>>
> >>>> I'm getting the folllowing BUG message on bootup with 3.10-rc5
> >>>>
> >>>> BUG: sleeping function called from invalid context at mm/slub.c:926
> >>>> in_atomic(): 1, irqs_disabled(): 128, pid: 1, name: swapper/0
> >>>> CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.10.0-rc5-gee3e35b-09316-ge78f3b35 #643
> >>>> [<c0014220>] (unwind_backtrace+0x0/0x120) from [<c001212c>] (show_stack+0x10/0x14)
> >>>> [<c001212c>] (show_stack+0x10/0x14) from [<c0143750>] (kmem_cache_alloc_trace+0x3c/0x210)
> >>>> [<c0143750>] (kmem_cache_alloc_trace+0x3c/0x210) from [<c00e0c60>] (request_threaded_irq+0x88/0x11c)
> >>>> [<c00e0c60>] (request_threaded_irq+0x88/0x11c) from [<c03bf53c>] (dwc3_gadget_start+0x198/0x200)
> >>>> [<c03bf53c>] (dwc3_gadget_start+0x198/0x200) from [<c03f7a5c>] (udc_bind_to_driver+0x70/0xd8)
> >>>> [<c03f7a5c>] (udc_bind_to_driver+0x70/0xd8) from [<c03f7b50>] (usb_gadget_probe_driver+0x8c/0xb8)
> >>>>
> >>>> and I suspect this problem was introduced in commit 8698e2acf
> >>>> (usb: dwc3: gadget: introduce and use enable/disable irq
> >>>> methods). Is there a fix for this problem? Can we just move the
> >>>> irq request outside the spinlock?
> >>> nice :-)
> >>>
> >>> how about this ?
> >> If start fails do you call stop? I believe the answer is no, so we'll
> >> need to free_irq() somewhere along the error path. Or we can request it
> >> after the spin_unlock()?
> > good point here's v2:
> 
> Ok looks good to me. I hope that platform_get_irq() doesn't fail,
> otherwise we're in for a nasty surprise. Maybe we should add a check in
> request_irq() for that case.

I don't think we would ever fall into that situation. And if we do, our
data (struct resource or DT) is f-ed up anyway :-)

-- 
balbi

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