linux-kernel - Re: [PATCH v4 5/9] usb: dwc3: core: make dual-role work with OTG irq

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Date:	Tue, 15 Sep 2015 17:46:26 +0300
From:	Roger Quadros <rogerq@...com>
To:	Peter Chen <peter.chen@...escale.com>, Felipe Balbi <balbi@...com>
CC:	<tony@...mide.com>, <Joao.Pinto@...opsys.com>,
	<sergei.shtylyov@...entembedded.com>, <jun.li@...escale.com>,
	<linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-omap@...r.kernel.org>
Subject: Re: [PATCH v4 5/9] usb: dwc3: core: make dual-role work with OTG irq

On 06/09/15 05:20, Peter Chen wrote:
> On Wed, Sep 02, 2015 at 09:43:38AM -0500, Felipe Balbi wrote:
>> Hi,
>>
>>> +
>>> +static irqreturn_t dwc3_otg_irq(int irq, void *_dwc)
>>> +{
>>> +	struct dwc3 *dwc = _dwc;
>>> +	irqreturn_t ret = IRQ_NONE;
>>> +	u32 reg;
>>> +
>>> +	spin_lock(&dwc->lock);
>>
>> this seems unnecessary, we're already in hardirq with IRQs disabled.
>> What sort of race could we have ? (in fact, this also needs change in
>> dwc3/gadget.c).
>>
> 
> Is it possible the kernel process is accessing the content you will 
> access?
> 
When kernel process accesses the data we'll never reach here
as we're protecting it with spinlock_irqsave(), spinunlock_irqrestore().

cheers,
-roger
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