Re: [PATCH] usbtest: Use boottime

[Felipe Balbi <balbi@xxxxxx>]

On Tue, Aug 11, 2015 at 11:57:15AM -0400, Abhilash Jindal wrote:
> Wall time obtained from do_gettimeofday is susceptible to sudden jumps due to
> user setting the time or due to NTP.  Boot time is constantly increasing time
> better suited for comparing two timestamps.
> 
> Signed-off-by: Abhilash Jindal <klock.android@xxxxxxxxx>
> ---
>  drivers/usb/misc/usbtest.c |   15 +++++----------
>  1 file changed, 5 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/usb/misc/usbtest.c b/drivers/usb/misc/usbtest.c
> index 0bbafe7..61cc639 100644
> --- a/drivers/usb/misc/usbtest.c
> +++ b/drivers/usb/misc/usbtest.c
> @@ -30,7 +30,7 @@ struct usbtest_param {
>  	unsigned		sglen;
>  
>  	/* outputs */
> -	struct timeval		duration;
> +	ktime_t		duration;
>  };
>  #define USBTEST_REQUEST	_IOWR('U', 100, struct usbtest_param)
>  
> @@ -2047,7 +2047,7 @@ usbtest_ioctl(struct usb_interface *intf, unsigned int code, void *buf)
>  	struct urb		*urb;
>  	struct scatterlist	*sg;
>  	struct usb_sg_request	req;
> -	struct timeval		start;
> +	ktime_t		start;
>  	unsigned		i;
>  
>  	/* FIXME USBDEVFS_CONNECTINFO doesn't say how fast the device is. */
> @@ -2095,7 +2095,7 @@ usbtest_ioctl(struct usb_interface *intf, unsigned int code, void *buf)
>  	 * FIXME add more tests!  cancel requests, verify the data, control
>  	 * queueing, concurrent read+write threads, and so on.
>  	 */
> -	do_gettimeofday(&start);
> +	start = ktime_get_boottime();
>  	switch (param->test_num) {
>  
>  	case 0:
> @@ -2487,13 +2487,8 @@ usbtest_ioctl(struct usb_interface *intf, unsigned int code, void *buf)
>  		simple_free_urb(urb);
>  		break;
>  	}
> -	do_gettimeofday(&param->duration);
> -	param->duration.tv_sec -= start.tv_sec;
> -	param->duration.tv_usec -= start.tv_usec;
> -	if (param->duration.tv_usec < 0) {
> -		param->duration.tv_usec += 1000 * 1000;
> -		param->duration.tv_sec -= 1;
> -	}
> +	param->duration = ktime_get_boottime();
> +	param->duration = ktime_sub(param->duration, start);

	param->duration = ktime_sub(ktime_get_boottime(), start);

-- 
balbi

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