Re: [PATCH v4] kcov, usb: only collect coverage from __usb_hcd_giveback_urb in softirq

[Sebastian Andrzej Siewior]

On 2020-10-16 15:57:45 [+0200], Andrey Konovalov wrote:
> --- a/drivers/usb/core/hcd.c
> +++ b/drivers/usb/core/hcd.c
> @@ -1646,9 +1646,16 @@ static void __usb_hcd_giveback_urb(struct urb *urb)
>  
>  	/* pass ownership to the completion handler */
>  	urb->status = status;
> -	kcov_remote_start_usb((u64)urb->dev->bus->busnum);
> +	/*
> +	 * This function can be called in task context inside another remote
> +	 * coverage collection section, but KCOV doesn't support that kind of
> +	 * recursion yet. Only collect coverage in softirq context for now.
> +	 */
> +	if (in_serving_softirq())

Could this in_serving_softirq() usage be replaced, please?  

> +		kcov_remote_start_usb((u64)urb->dev->bus->busnum);
>  	urb->complete(urb);
> -	kcov_remote_stop();
> +	if (in_serving_softirq())
> +		kcov_remote_stop();
>  
>  	usb_anchor_resume_wakeups(anchor);
>  	atomic_dec(&urb->use_count);

Sebastian