linux-kernel - Re: [PATCH] USB: EHCI: fix scheduling while atomic during suspend

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Date:	Thu, 27 Jan 2011 10:36:15 -0500 (EST)
From:	Alan Stern <stern@...land.harvard.edu>
To:	Yin Kangkai <kangkai.yin@...el.com>
cc:	linux-usb@...r.kernel.org, Greg Kroah-Hartman <gregkh@...e.de>,
	David Brownell <dbrownell@...rs.sourceforge.net>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] USB: EHCI: fix scheduling while atomic during suspend

On Thu, 27 Jan 2011, Yin Kangkai wrote:

> There is a msleep with spin lock held during ehci pci suspend, which will
> cause kernel BUG: scheduling while atomic. Fix that.

> diff --git a/drivers/usb/host/ehci-hub.c b/drivers/usb/host/ehci-hub.c
> index 86f0815..a16c94a 100644
> --- a/drivers/usb/host/ehci-hub.c
> +++ b/drivers/usb/host/ehci-hub.c
> @@ -111,14 +111,19 @@ static void ehci_adjust_port_wakeup_flags(struct ehci_hcd *ehci,
>  {
>  	int		port;
>  	u32		temp;
> +	unsigned long	flags;
> +
> +	spin_lock_irqsave(&ehci->lock, flags);
>  
>  	/* If remote wakeup is enabled for the root hub but disabled
>  	 * for the controller, we must adjust all the port wakeup flags
>  	 * when the controller is suspended or resumed.  In all other
>  	 * cases they don't need to be changed.
>  	 */
> -	if (!ehci_to_hcd(ehci)->self.root_hub->do_remote_wakeup || do_wakeup)
> +	if (!ehci_to_hcd(ehci)->self.root_hub->do_remote_wakeup || do_wakeup) {
> +		spin_unlock_irqrestore(&ehci->lock, flags);
>  		return;
> +	}

You should move the spin_lock_irqsave() down to here.  Then the 
spin_unlock_irqrestore() above won't be needed.

Alan Stern

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