linux-kernel - Re: [PATCH] usb: dwc3: gadget: Avoid race between dwc3 interrupt handler and irq thread handler

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Message-ID: <874m1p3a3v.fsf@linux.intel.com>
Date:   Tue, 27 Dec 2016 13:05:56 +0200
From:   Felipe Balbi <balbi@...nel.org>
To:     Lu Baolu <baolu.lu@...ux.intel.com>,
        Baolin Wang <baolin.wang@...aro.org>,
        gregkh@...uxfoundation.org
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        linaro-kernel@...ts.linaro.org, broonie@...nel.org
Subject: Re: [PATCH] usb: dwc3: gadget: Avoid race between dwc3 interrupt handler and irq thread handler

Hi,

Lu Baolu <baolu.lu@...ux.intel.com> writes:
> On 12/26/2016 04:01 PM, Baolin Wang wrote:
>> On some platfroms(like x86 platform), when one core is running the USB gadget
>> irq thread handler by dwc3_thread_interrupt(), meanwhile another core also can
>> respond other interrupts from dwc3 controller and modify the event buffer by
>> dwc3_interrupt() function, that will cause getting the wrong event count in
>> irq thread handler to make the USB function abnormal.
>>
>> We should add spin_lock/unlock() in dwc3_check_event_buf() to avoid this race.
>
> Why not spin_lock_irq ones? This lock seems to be used in both
> normal and interrupt threads. Or, I missed anything?

this is top half handler. Interrupts are already disabled.

-- 
balbi

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