[PATCH] usb: core: hub: fix race condition about TRSMRCY of resume

[Alan Stern]

On Tue, May 11, 2021 at 06:15:22PM +0800, Chunfeng Yun wrote:
> This may happen if the port becomes resume status exactly
> when usb_port_resume() gets port status, it still need provide
> a TRSMCRY time before access the device.
> 
> Reported-by: Tianping Fang <tianping.fang at mediatek.com>
> Signed-off-by: Chunfeng Yun <chunfeng.yun at mediatek.com>

This should also say:

CC: <stable at vger.kernel.org>

> ---
>  drivers/usb/core/hub.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
> index b2bc4b7c4289..fc7d6cdacf16 100644
> --- a/drivers/usb/core/hub.c
> +++ b/drivers/usb/core/hub.c
> @@ -3642,9 +3642,6 @@ int usb_port_resume(struct usb_device *udev, pm_message_t msg)
>  		 * sequence.
>  		 */
>  		status = hub_port_status(hub, port1, &portstatus, &portchange);
> -
> -		/* TRSMRCY = 10 msec */
> -		msleep(10);
>  	}
>  
>   SuspendCleared:
> @@ -3659,6 +3656,9 @@ int usb_port_resume(struct usb_device *udev, pm_message_t msg)
>  				usb_clear_port_feature(hub->hdev, port1,
>  						USB_PORT_FEAT_C_SUSPEND);
>  		}
> +
> +		/* TRSMRCY = 10 msec */
> +		msleep(10);
>  	}
>  
>  	if (udev->persist_enabled)

Acked-by: Alan Stern <stern at rowland.harvard.edu>