From: John Youn <John.Youn@synopsys.com>
To: Felipe Balbi <balbi@kernel.org>,
Janusz Dziedzic <janusz.dziedzic@gmail.com>
Cc: Lu Baolu <baolu.lu@linux.intel.com>,
Baolin Wang <baolin.wang@linaro.org>,
Greg KH <gregkh@linuxfoundation.org>,
USB <linux-usb@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Linaro Kernel Mailman List <linaro-kernel@lists.linaro.org>,
Mark Brown <broonie@kernel.org>
Subject: RE: [PATCH] usb: dwc3: gadget: Avoid race between dwc3 interrupt handler and irq thread handler
Date: Thu, 29 Dec 2016 01:29:49 +0000 [thread overview]
Message-ID: <2B3535C5ECE8B5419E3ECBE300772909021B3DECCC@US01WEMBX2.internal.synopsys.com> (raw)
In-Reply-To: <87o9zwauwu.fsf@linux.intel.com>
> -----Original Message-----
> From: linux-usb-owner@vger.kernel.org [mailto:linux-usb-
> owner@vger.kernel.org] On Behalf Of Felipe Balbi
> Sent: Wednesday, December 28, 2016 8:19 AM
> To: Janusz Dziedzic <janusz.dziedzic@gmail.com>
> Cc: Lu Baolu <baolu.lu@linux.intel.com>; Baolin Wang
> <baolin.wang@linaro.org>; Greg KH <gregkh@linuxfoundation.org>; USB
> <linux-usb@vger.kernel.org>; LKML <linux-kernel@vger.kernel.org>; Linaro
> Kernel Mailman List <linaro-kernel@lists.linaro.org>; Mark Brown
> <broonie@kernel.org>
> Subject: Re: [PATCH] usb: dwc3: gadget: Avoid race between dwc3 interrupt
> handler and irq thread handler
>
>
> Hi,
>
> Janusz Dziedzic <janusz.dziedzic@gmail.com> writes:
> >>>> 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.
> >>
> > BTW,
> > We don't use spin_lock in top half handler.
> > Maybe we should/can switch all spin_lock_irqsave() to simple
> > spin_lock() in the thread/callbacks?
>
> in theory, yes we've masked all interrupts from this controller for the
> duration of the thread handler. However this breaks networking
> gadgets. I can only guess network stack has a hard requirement to run
> with IRQs disabled.
>
Hi,
Is this version 3.00a of the core?
That version has a STAR where the interrupts cannot be masked. That results in similar symptoms to what you're seeing here.
Regards,
John
next prev parent reply other threads:[~2016-12-29 1:39 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-26 8:01 [PATCH] usb: dwc3: gadget: Avoid race between dwc3 interrupt handler and irq thread handler Baolin Wang
2016-12-27 2:39 ` Lu Baolu
2016-12-27 2:58 ` Baolin Wang
2016-12-27 4:45 ` Lu Baolu
2016-12-27 11:05 ` Felipe Balbi
2016-12-28 15:27 ` Janusz Dziedzic
2016-12-28 16:19 ` Felipe Balbi
2016-12-29 1:29 ` John Youn [this message]
2017-01-05 19:08 ` John Youn
2017-01-06 2:44 ` Baolin Wang
2016-12-27 10:52 ` Janusz Dziedzic
2016-12-27 11:06 ` Baolin Wang
2016-12-27 11:11 ` Felipe Balbi
2016-12-27 12:16 ` Baolin Wang
2016-12-28 12:30 ` Janusz Dziedzic
2017-01-03 12:21 ` Baolin Wang
2017-01-03 12:33 ` Felipe Balbi
2017-01-05 2:07 ` Baolin Wang
2017-01-05 9:26 ` Felipe Balbi
2017-01-05 9:43 ` Baolin Wang
2017-01-05 11:19 ` Felipe Balbi
2017-01-05 12:03 ` Baolin Wang
2016-12-27 11:07 ` Felipe Balbi
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