linux-kernel - Re: [PATCH] usb: dwc2: host: Protect PCGCTL with lock in dwc2_port

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Date:	Fri, 16 Oct 2015 18:06:01 +0000
From:	John Youn <John.Youn@...opsys.com>
To:	Douglas Anderson <dianders@...omium.org>,
	John Youn <John.Youn@...opsys.com>,
	"balbi@...com" <balbi@...com>
CC:	Yunzhi Li <lyz@...k-chips.com>,
	Heiko Stübner <heiko@...ech.de>,
	"linux-rockchip@...ts.infradead.org" 
	<linux-rockchip@...ts.infradead.org>,
	Julius Werner <jwerner@...omium.org>,
	"gregory.herrero@...el.com" <gregory.herrero@...el.com>,
	"yousaf.kaukab@...el.com" <yousaf.kaukab@...el.com>,
	"dinguyen@...nsource.altera.com" <dinguyen@...nsource.altera.com>,
	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] usb: dwc2: host: Protect PCGCTL with lock in
 dwc2_port_resume()

On 10/14/2015 3:58 PM, Douglas Anderson wrote:
> From code inspection, it appears to be unsafe to do a read-modify-write
> of PCGCTL in dwc2_port_resume().  Let's make sure the spinlock is held
> around this operation.
> 
> Signed-off-by: Douglas Anderson <dianders@...omium.org>
> ---
>  drivers/usb/dwc2/hcd.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c
> index af4e4a2..e79baf7 100644
> --- a/drivers/usb/dwc2/hcd.c
> +++ b/drivers/usb/dwc2/hcd.c
> @@ -1500,6 +1500,8 @@ static void dwc2_port_resume(struct dwc2_hsotg *hsotg)
>  	u32 hprt0;
>  	u32 pcgctl;
>  
> +	spin_lock_irqsave(&hsotg->lock, flags);
> +
>  	/*
>  	 * If hibernation is supported, Phy clock is already resumed
>  	 * after registers restore.
> @@ -1508,10 +1510,11 @@ static void dwc2_port_resume(struct dwc2_hsotg *hsotg)
>  		pcgctl = dwc2_readl(hsotg->regs + PCGCTL);
>  		pcgctl &= ~PCGCTL_STOPPCLK;
>  		dwc2_writel(pcgctl, hsotg->regs + PCGCTL);
> +		spin_unlock_irqrestore(&hsotg->lock, flags);
>  		usleep_range(20000, 40000);
> +		spin_lock_irqsave(&hsotg->lock, flags);
>  	}
>  
> -	spin_lock_irqsave(&hsotg->lock, flags);
>  	hprt0 = dwc2_read_hprt0(hsotg);
>  	hprt0 |= HPRT0_RES;
>  	hprt0 &= ~HPRT0_SUSP;
> 


Acked-by: John Youn <johnyoun@...opsys.com>


John

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