From: Janusz Dziedzic <janusz.dziedzic@gmail.com>
To: Baolin Wang <baolin.wang@linaro.org>
Cc: balbi@kernel.org, gregkh@linuxfoundation.org,
linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
linaro-kernel@lists.linaro.org, broonie@kernel.org
Subject: Re: [PATCH] usb: dwc3: gadget: Avoid race between dwc3 interrupt handler and irq thread handler
Date: Tue, 27 Dec 2016 11:52:15 +0100 [thread overview]
Message-ID: <CAFED-j=mo2kSc8VBzgw6F9up3Dp8LB79dFAcAr+4baZ18jbXMQ@mail.gmail.com> (raw)
In-Reply-To: <0d79eb1f34e409749a136173b68f365b545c4789.1482738764.git.baolin.wang@linaro.org>
2016-12-26 9:01 GMT+01:00 Baolin Wang <baolin.wang@linaro.org>:
> 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.
>
Interesting, I always think we mask interrupt in dwc3_interrupt() by setting
DWC3_GEVNTSIZ_INTMASK
And unmask interrupt when we end dwc3_thread_interrupt().
So, we shouldn't get any IRQ from HW during dwc3_thread_interrupt(),
or I miss something?
Do you have some traces that indicate this masking will not work correctly?
BTW, what value you get when problem occured, 0xFFFC?
BR
Janusz
> Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
> ---
> drivers/usb/dwc3/gadget.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index 6785595..1a1e1f4 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -2894,10 +2894,13 @@ static irqreturn_t dwc3_check_event_buf(struct dwc3_event_buffer *evt)
> return IRQ_HANDLED;
> }
>
> + spin_lock(&dwc->lock);
> count = dwc3_readl(dwc->regs, DWC3_GEVNTCOUNT(0));
> count &= DWC3_GEVNTCOUNT_MASK;
> - if (!count)
> + if (!count) {
> + spin_unlock(&dwc->lock);
> return IRQ_NONE;
> + }
>
> evt->count = count;
> evt->flags |= DWC3_EVENT_PENDING;
> @@ -2914,6 +2917,7 @@ static irqreturn_t dwc3_check_event_buf(struct dwc3_event_buffer *evt)
> memcpy(evt->cache, evt->buf, count - amount);
>
> dwc3_writel(dwc->regs, DWC3_GEVNTCOUNT(0), count);
> + spin_unlock(&dwc->lock);
>
> return IRQ_WAKE_THREAD;
> }
> --
> 1.7.9.5
>
> --
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> More majordomo info at http://vger.kernel.org/majordomo-info.html
--
Janusz Dziedzic
next prev parent reply other threads:[~2016-12-27 10:52 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
2017-01-05 19:08 ` John Youn
2017-01-06 2:44 ` Baolin Wang
2016-12-27 10:52 ` Janusz Dziedzic [this message]
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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