Commit ebf918cf authored by Tina Ruchandani's avatar Tina Ruchandani Committed by David S. Miller
Browse files

isdn: Use ktime_t instead of 'struct timeval' 



'struct timeval' uses 32-bit representation for seconds which will
overflow in year 2038 and beyond. mISDN/clock.c needs to compute and
store elapsed time in intervals of 125 microseconds. This patch replaces
the usage of 'struct timeval' with 64-bit ktime_t which is y2038 safe.
The patch also replaces do_gettimeofday() (wall-clock time) with
ktime_get() (monotonic time) since we only care about elapsed time here.

Signed-off-by: default avatarTina Ruchandani <ruchandani.tina@gmail.com>
Suggested-by: default avatarArnd Bergmnann <arnd@arndb.de>
Suggested-by: default avatarDavid Miller <davem@davemloft.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 4320f219

drivers/isdn/mISDN/clock.c

+29 −40
Original line number Diff line number Diff line
@@ -37,6 +37,7 @@ 
#include <linux/types.h>

#include <linux/stddef.h>

#include <linux/spinlock.h>

#include <linux/ktime.h>

#include <linux/mISDNif.h>

#include <linux/export.h>

#include "core.h"
@@ -45,15 +46,15 @@ static u_int *debug; 
static LIST_HEAD(iclock_list);

static DEFINE_RWLOCK(iclock_lock);

static u16 iclock_count;		/* counter of last clock */

static struct timeval iclock_tv;	/* time stamp of last clock */

static int iclock_tv_valid;		/* already received one timestamp */

static ktime_t iclock_timestamp;	/* time stamp of last clock */

static int iclock_timestamp_valid;	/* already received one timestamp */

static struct mISDNclock *iclock_current;



void

mISDN_init_clock(u_int *dp)

{

	debug = dp;

	do_gettimeofday(&iclock_tv);

	iclock_timestamp = ktime_get();

}



static void
@@ -86,7 +87,7 @@ select_iclock(void) 
	}

	if (bestclock != iclock_current) {

		/* no clock received yet */

		iclock_tv_valid = 0;

		iclock_timestamp_valid = 0;

	}

	iclock_current = bestclock;

}
@@ -139,12 +140,11 @@ mISDN_unregister_clock(struct mISDNclock *iclock) 
EXPORT_SYMBOL(mISDN_unregister_clock);



void

mISDN_clock_update(struct mISDNclock *iclock, int samples, struct timeval *tv)

mISDN_clock_update(struct mISDNclock *iclock, int samples, ktime_t *timestamp)

{

	u_long		flags;

	struct timeval	tv_now;

	time_t		elapsed_sec;

	int		elapsed_8000th;

	ktime_t		timestamp_now;

	u16		delta;



	write_lock_irqsave(&iclock_lock, flags);

	if (iclock_current != iclock) {
@@ -156,33 +156,27 @@ mISDN_clock_update(struct mISDNclock *iclock, int samples, struct timeval *tv) 
		write_unlock_irqrestore(&iclock_lock, flags);

		return;

	}

	if (iclock_tv_valid) {

	if (iclock_timestamp_valid) {

		/* increment sample counter by given samples */

		iclock_count += samples;

		if (tv) { /* tv must be set, if function call is delayed */

			iclock_tv.tv_sec = tv->tv_sec;

			iclock_tv.tv_usec = tv->tv_usec;

		} else

			do_gettimeofday(&iclock_tv);

		if (timestamp) { /* timestamp must be set, if function call is delayed */

			iclock_timestamp = *timestamp;

		} else	{

			iclock_timestamp = ktime_get();

		}

	} else {

		/* calc elapsed time by system clock */

		if (tv) { /* tv must be set, if function call is delayed */

			tv_now.tv_sec = tv->tv_sec;

			tv_now.tv_usec = tv->tv_usec;

		} else

			do_gettimeofday(&tv_now);

		elapsed_sec = tv_now.tv_sec - iclock_tv.tv_sec;

		elapsed_8000th = (tv_now.tv_usec / 125)

			- (iclock_tv.tv_usec / 125);

		if (elapsed_8000th < 0) {

			elapsed_sec -= 1;

			elapsed_8000th += 8000;

		if (timestamp) { /* timestamp must be set, if function call is delayed */

			timestamp_now = *timestamp;

		} else {

			timestamp_now = ktime_get();

		}

		delta = ktime_divns(ktime_sub(timestamp_now, iclock_timestamp),

				(NSEC_PER_SEC / 8000));

		/* add elapsed time to counter and set new timestamp */

		iclock_count += elapsed_sec * 8000 + elapsed_8000th;

		iclock_tv.tv_sec = tv_now.tv_sec;

		iclock_tv.tv_usec = tv_now.tv_usec;

		iclock_tv_valid = 1;

		iclock_count += delta;

		iclock_timestamp = timestamp_now;

		iclock_timestamp_valid = 1;

		if (*debug & DEBUG_CLOCK)

			printk("Received first clock from source '%s'.\n",

			       iclock_current ? iclock_current->name : "nothing");
@@ -195,22 +189,17 @@ unsigned short 
mISDN_clock_get(void)

{

	u_long		flags;

	struct timeval	tv_now;

	time_t		elapsed_sec;

	int		elapsed_8000th;

	ktime_t		timestamp_now;

	u16		delta;

	u16		count;



	read_lock_irqsave(&iclock_lock, flags);

	/* calc elapsed time by system clock */

	do_gettimeofday(&tv_now);

	elapsed_sec = tv_now.tv_sec - iclock_tv.tv_sec;

	elapsed_8000th = (tv_now.tv_usec / 125) - (iclock_tv.tv_usec / 125);

	if (elapsed_8000th < 0) {

		elapsed_sec -= 1;

		elapsed_8000th += 8000;

	}

	timestamp_now = ktime_get();

	delta = ktime_divns(ktime_sub(timestamp_now, iclock_timestamp),

			(NSEC_PER_SEC / 8000));

	/* add elapsed time to counter */

	count =	iclock_count + elapsed_sec * 8000 + elapsed_8000th;

	count =	iclock_count + delta;

	read_unlock_irqrestore(&iclock_lock, flags);

	return count;

}

include/linux/mISDNif.h

+1 −1
Original line number Diff line number Diff line
@@ -596,7 +596,7 @@ static inline struct mISDNdevice *dev_to_mISDN(struct device *dev) 
}



extern void	set_channel_address(struct mISDNchannel *, u_int, u_int);

extern void	mISDN_clock_update(struct mISDNclock *, int, struct timeval *);

extern void	mISDN_clock_update(struct mISDNclock *, int, ktime_t *);

extern unsigned short mISDN_clock_get(void);

extern const char *mISDNDevName4ch(struct mISDNchannel *);

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