linux-kernel - [PATCH 2/2] usbip: use monotonic timestamps

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Date:   Tue,  7 Nov 2017 11:39:57 +0100
From:   Arnd Bergmann <arnd@...db.de>
To:     Valentina Manea <valentina.manea.m@...il.com>,
        Shuah Khan <shuah@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Arnd Bergmann <arnd@...db.de>, Johan Hovold <johan@...nel.org>,
        Felipe Balbi <felipe.balbi@...ux.intel.com>,
        Krzysztof Opasiak <k.opasiak@...sung.com>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] usbip: use monotonic timestamps

This gets rid of the deprecated do_gettimeofday() function in usbip.
The comment above vgadget_get_frame() mentions that it suffers
from issues with the time jumps due to suspend and settimeofday,
so I'm changing it to use ktime_get_ts64() to use monotonic times
that don't have this problem.

I couldn't tell whether we should use CLOCK_MONOTONIC or
CLOCK_MONOTONIC_RAW here, the difference being the exact rate
when correcting for NTP. I picked monotonic time since it doesn't
change the speed to the existing code and should be better
synchronized with other machines we talk to.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 drivers/usb/usbip/vudc.h       | 2 +-
 drivers/usb/usbip/vudc_dev.c   | 7 +++----
 drivers/usb/usbip/vudc_sysfs.c | 2 +-
 3 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/usbip/vudc.h b/drivers/usb/usbip/vudc.h
index 44fb24193acd..8282362176d5 100644
--- a/drivers/usb/usbip/vudc.h
+++ b/drivers/usb/usbip/vudc.h
@@ -105,7 +105,7 @@ struct vudc {
 
 	struct usbip_device ud;
 	struct transfer_timer tr_timer;
-	struct timeval start_time;
+	struct timespec64 start_time;
 
 	struct list_head urb_queue;
 
diff --git a/drivers/usb/usbip/vudc_dev.c b/drivers/usb/usbip/vudc_dev.c
index 16fb4f85a6f6..fe07e799e481 100644
--- a/drivers/usb/usbip/vudc_dev.c
+++ b/drivers/usb/usbip/vudc_dev.c
@@ -136,15 +136,14 @@ struct vep *vudc_find_endpoint(struct vudc *udc, u8 address)
 
 /* gadget ops */
 
-/* FIXME - this will probably misbehave when suspend/resume is added */
 static int vgadget_get_frame(struct usb_gadget *_gadget)
 {
-	struct timeval now;
+	struct timespec64 now;
 	struct vudc *udc = usb_gadget_to_vudc(_gadget);
 
-	do_gettimeofday(&now);
+	ktime_get_ts64(&now);
 	return ((now.tv_sec - udc->start_time.tv_sec) * 1000 +
-			(now.tv_usec - udc->start_time.tv_usec) / 1000)
+		(now.tv_nsec - udc->start_time.tv_nsec) / NSEC_PER_MSEC)
 			& 0x7FF;
 }
 
diff --git a/drivers/usb/usbip/vudc_sysfs.c b/drivers/usb/usbip/vudc_sysfs.c
index 7d978b824ed4..49e0123caa53 100644
--- a/drivers/usb/usbip/vudc_sysfs.c
+++ b/drivers/usb/usbip/vudc_sysfs.c
@@ -162,7 +162,7 @@ static ssize_t store_sockfd(struct device *dev, struct device_attribute *attr,
 		udc->ud.status = SDEV_ST_USED;
 		spin_unlock_irq(&udc->ud.lock);
 
-		do_gettimeofday(&udc->start_time);
+		ktime_get_ts64(&udc->start_time);
 		v_start_timer(udc);
 		udc->connected = 1;
 	} else {
-- 
2.9.0