Re: [PATCH 1/1] usb: chipidea: udc: fix sleeping function called from invalid context

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On Tue, 10 Mar 2020, Peter Chen wrote:

> From: Peter Chen <peter.chen@xxxxxxx>
> 
> The code calls pm_runtime_get_sync with irq disabled, it causes below
> warning:
> 
> BUG: sleeping function called from invalid context at
> wer/runtime.c:1075
> in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid:
> er/u8:1

...

> Tested-by: Dmitry Osipenko <digetx@xxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx> #v5.5
> Fixes: 72dc8df7920f ("usb: chipidea: udc: protect usb interrupt enable")
> Reported-by: Dmitry Osipenko <digetx@xxxxxxxxx>
> Signed-off-by: Peter Chen <peter.chen@xxxxxxx>
> ---
>  drivers/usb/chipidea/udc.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/chipidea/udc.c b/drivers/usb/chipidea/udc.c
> index ffaf46f5d062..1fa587ec52fc 100644
> --- a/drivers/usb/chipidea/udc.c
> +++ b/drivers/usb/chipidea/udc.c
> @@ -1539,9 +1539,11 @@ static void ci_hdrc_gadget_connect(struct usb_gadget *_gadget, int is_active)
>  		if (ci->driver) {
>  			hw_device_state(ci, ci->ep0out->qh.dma);
>  			usb_gadget_set_state(_gadget, USB_STATE_POWERED);
> +			spin_unlock_irqrestore(&ci->lock, flags);
>  			usb_udc_vbus_handler(_gadget, true);
> +		} else {
> +			spin_unlock_irqrestore(&ci->lock, flags);
>  		}
> -		spin_unlock_irqrestore(&ci->lock, flags);

There's something strange about this patch.

Do you really know that interrupts will be enabled following the 
spin_unlock_irqrestore()?  In other words, do you know that interrupts 
were enabled upon entry to this routine?

If they were, then why use spin_lock_irqsave/spin_unlock_irqrestore?  
Why not use spin_lock_irq and spin_unlock_irq?

Alan Stern




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