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   /*
    *  linux/kernel/time.c
    *
    *  Copyright (C) 1991, 1992  Linus Torvalds
    *
    *  This file contains the interface functions for the various
    *  time related system calls: time, stime, gettimeofday, settimeofday,
    *                             adjtime
    */
  /*
   * Modification history kernel/time.c
   *
   * 1993-09-02    Philip Gladstone
   *      Created file with time related functions from sched.c and adjtimex()
   * 1993-10-08    Torsten Duwe
   *      adjtime interface update and CMOS clock write code
   * 1995-08-13    Torsten Duwe
   *      kernel PLL updated to 1994-12-13 specs (rfc-1589)
   * 1999-01-16    Ulrich Windl
   *      Introduced error checking for many cases in adjtimex().
   *      Updated NTP code according to technical memorandum Jan '96
   *      "A Kernel Model for Precision Timekeeping" by Dave Mills
   *      Allow time_constant larger than MAXTC(6) for NTP v4 (MAXTC == 10)
   *      (Even though the technical memorandum forbids it)
   * 2004-07-14    Christoph Lameter
   *      Added getnstimeofday to allow the posix timer functions to return
   *      with nanosecond accuracy
   */
  
  #include <linux/module.h>
  #include <linux/timex.h>
  #include <linux/capability.h>
  #include <linux/clocksource.h>
  #include <linux/errno.h>
  #include <linux/syscalls.h>
  #include <linux/security.h>
  #include <linux/fs.h>
  #include <linux/slab.h>
  #include <linux/math64.h>
  #include <linux/ptrace.h>
  
  #include <asm/uaccess.h>
  #include <asm/unistd.h>
  
  #include "timeconst.h"
  
  /*
   * The timezone where the local system is located.  Used as a default by some
   * programs who obtain this value by using gettimeofday.
   */
  struct timezone sys_tz;
  
  EXPORT_SYMBOL(sys_tz);
  
  #ifdef __ARCH_WANT_SYS_TIME
  
  /*
   * sys_time() can be implemented in user-level using
   * sys_gettimeofday().  Is this for backwards compatibility?  If so,
   * why not move it into the appropriate arch directory (for those
   * architectures that need it).
   */
  SYSCALL_DEFINE1(time, time_t __user *, tloc)
  {
          time_t i = get_seconds();
  
          if (tloc) {
                  if (put_user(i,tloc))
                          return -EFAULT;
          }
          force_successful_syscall_return();
          return i;
  }
  
  /*
   * sys_stime() can be implemented in user-level using
   * sys_settimeofday().  Is this for backwards compatibility?  If so,
   * why not move it into the appropriate arch directory (for those
   * architectures that need it).
   */
  
  SYSCALL_DEFINE1(stime, time_t __user *, tptr)
  {
          struct timespec tv;
          int err;
  
          if (get_user(tv.tv_sec, tptr))
                  return -EFAULT;
  
          tv.tv_nsec = 0;
  
          err = security_settime(&tv, NULL);
          if (err)
                  return err;
  
          do_settimeofday(&tv);
          return 0;
  }
  
 #endif /* __ARCH_WANT_SYS_TIME */
 
 SYSCALL_DEFINE2(gettimeofday, struct timeval __user *, tv,
                 struct timezone __user *, tz)
 {
         if (likely(tv != NULL)) {
                 struct timeval ktv;
                 do_gettimeofday(&ktv);
                 if (copy_to_user(tv, &ktv, sizeof(ktv)))
                         return -EFAULT;
         }
         if (unlikely(tz != NULL)) {
                 if (copy_to_user(tz, &sys_tz, sizeof(sys_tz)))
                         return -EFAULT;
         }
         return 0;
 }
 
 /*
  * Adjust the time obtained from the CMOS to be UTC time instead of
  * local time.
  *
  * This is ugly, but preferable to the alternatives.  Otherwise we
  * would either need to write a program to do it in /etc/rc (and risk
  * confusion if the program gets run more than once; it would also be
  * hard to make the program warp the clock precisely n hours)  or
  * compile in the timezone information into the kernel.  Bad, bad....
  *
  *                                              - TYT, 1992-01-01
  *
  * The best thing to do is to keep the CMOS clock in universal time (UTC)
  * as real UNIX machines always do it. This avoids all headaches about
  * daylight saving times and warping kernel clocks.
  */
 static inline void warp_clock(void)
 {
         write_seqlock_irq(&xtime_lock);
         wall_to_monotonic.tv_sec -= sys_tz.tz_minuteswest * 60;
         xtime.tv_sec += sys_tz.tz_minuteswest * 60;
         update_xtime_cache(0);
         write_sequnlock_irq(&xtime_lock);
         clock_was_set();
 }
 
 /*
  * In case for some reason the CMOS clock has not already been running
  * in UTC, but in some local time: The first time we set the timezone,
  * we will warp the clock so that it is ticking UTC time instead of
  * local time. Presumably, if someone is setting the timezone then we
  * are running in an environment where the programs understand about
  * timezones. This should be done at boot time in the /etc/rc script,
  * as soon as possible, so that the clock can be set right. Otherwise,
  * various programs will get confused when the clock gets warped.
  */
 
 int do_sys_settimeofday(struct timespec *tv, struct timezone *tz)
 {
         static int firsttime = 1;
         int error = 0;
 
         if (tv && !timespec_valid(tv))
                 return -EINVAL;
 
         error = security_settime(tv, tz);
         if (error)
                 return error;
 
         if (tz) {
                 /* SMP safe, global irq locking makes it work. */
                 sys_tz = *tz;
                 update_vsyscall_tz();
                 if (firsttime) {
                         firsttime = 0;
                         if (!tv)
                                 warp_clock();
                 }
         }
         if (tv)
         {
                 /* SMP safe, again the code in arch/foo/time.c should
                  * globally block out interrupts when it runs.
                  */
                 return do_settimeofday(tv);
         }
         return 0;
 }
 
 SYSCALL_DEFINE2(settimeofday, struct timeval __user *, tv,
                 struct timezone __user *, tz)
 {
         struct timeval user_tv;
         struct timespec new_ts;
         struct timezone new_tz;
 
         if (tv) {
                 if (copy_from_user(&user_tv, tv, sizeof(*tv)))
                         return -EFAULT;
                 new_ts.tv_sec = user_tv.tv_sec;
                 new_ts.tv_nsec = user_tv.tv_usec * NSEC_PER_USEC;
         }
         if (tz) {
                 if (copy_from_user(&new_tz, tz, sizeof(*tz)))
                         return -EFAULT;
         }
 
         return do_sys_settimeofday(tv ? &new_ts : NULL, tz ? &new_tz : NULL);
 }
 
 SYSCALL_DEFINE1(adjtimex, struct timex __user *, txc_p)
 {
         struct timex txc;               /* Local copy of parameter */
         int ret;
 
         /* Copy the user data space into the kernel copy
          * structure. But bear in mind that the structures
          * may change
          */
         if(copy_from_user(&txc, txc_p, sizeof(struct timex)))
                 return -EFAULT;
         ret = do_adjtimex(&txc);
         return copy_to_user(txc_p, &txc, sizeof(struct timex)) ? -EFAULT : ret;
 }
 
 /**
  * current_fs_time - Return FS time
  * @sb: Superblock.
  *
  * Return the current time truncated to the time granularity supported by
  * the fs.
  */
 struct timespec current_fs_time(struct super_block *sb)
 {
         struct timespec now = current_kernel_time();
         return timespec_trunc(now, sb->s_time_gran);
 }
 EXPORT_SYMBOL(current_fs_time);
 
 /*
  * Convert jiffies to milliseconds and back.
  *
  * Avoid unnecessary multiplications/divisions in the
  * two most common HZ cases:
  */
 unsigned int inline jiffies_to_msecs(const unsigned long j)
 {
 #if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ)
         return (MSEC_PER_SEC / HZ) * j;
 #elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC)
         return (j + (HZ / MSEC_PER_SEC) - 1)/(HZ / MSEC_PER_SEC);
 #else
 # if BITS_PER_LONG == 32
         return (HZ_TO_MSEC_MUL32 * j) >> HZ_TO_MSEC_SHR32;
 # else
         return (j * HZ_TO_MSEC_NUM) / HZ_TO_MSEC_DEN;
 # endif
 #endif
 }
 EXPORT_SYMBOL(jiffies_to_msecs);
 
 unsigned int inline jiffies_to_usecs(const unsigned long j)
 {
 #if HZ <= USEC_PER_SEC && !(USEC_PER_SEC % HZ)
         return (USEC_PER_SEC / HZ) * j;
 #elif HZ > USEC_PER_SEC && !(HZ % USEC_PER_SEC)
         return (j + (HZ / USEC_PER_SEC) - 1)/(HZ / USEC_PER_SEC);
 #else
 # if BITS_PER_LONG == 32
         return (HZ_TO_USEC_MUL32 * j) >> HZ_TO_USEC_SHR32;
 # else
         return (j * HZ_TO_USEC_NUM) / HZ_TO_USEC_DEN;
 # endif
 #endif
 }
 EXPORT_SYMBOL(jiffies_to_usecs);
 
 /**
  * timespec_trunc - Truncate timespec to a granularity
  * @t: Timespec
  * @gran: Granularity in ns.
  *
  * Truncate a timespec to a granularity. gran must be smaller than a second.
  * Always rounds down.
  *
  * This function should be only used for timestamps returned by
  * current_kernel_time() or CURRENT_TIME, not with do_gettimeofday() because
  * it doesn't handle the better resolution of the latter.
  */
 struct timespec timespec_trunc(struct timespec t, unsigned gran)
 {
         /*
          * Division is pretty slow so avoid it for common cases.
          * Currently current_kernel_time() never returns better than
          * jiffies resolution. Exploit that.
          */
         if (gran <= jiffies_to_usecs(1) * 1000) {
                 /* nothing */
         } else if (gran == 1000000000) {
                 t.tv_nsec = 0;
         } else {
                 t.tv_nsec -= t.tv_nsec % gran;
         }
         return t;
 }
 EXPORT_SYMBOL(timespec_trunc);
 
 #ifndef CONFIG_GENERIC_TIME
 /*
  * Simulate gettimeofday using do_gettimeofday which only allows a timeval
  * and therefore only yields usec accuracy
  */
 void getnstimeofday(struct timespec *tv)
 {
         struct timeval x;
 
         do_gettimeofday(&x);
         tv->tv_sec = x.tv_sec;
         tv->tv_nsec = x.tv_usec * NSEC_PER_USEC;
 }
 EXPORT_SYMBOL_GPL(getnstimeofday);
 #endif
 
 /* Converts Gregorian date to seconds since 1970-01-01 00:00:00.
  * Assumes input in normal date format, i.e. 1980-12-31 23:59:59
  * => year=1980, mon=12, day=31, hour=23, min=59, sec=59.
  *
  * [For the Julian calendar (which was used in Russia before 1917,
  * Britain & colonies before 1752, anywhere else before 1582,
  * and is still in use by some communities) leave out the
  * -year/100+year/400 terms, and add 10.]
  *
  * This algorithm was first published by Gauss (I think).
  *
  * WARNING: this function will overflow on 2106-02-07 06:28:16 on
  * machines where long is 32-bit! (However, as time_t is signed, we
  * will already get problems at other places on 2038-01-19 03:14:08)
  */
 unsigned long
 mktime(const unsigned int year0, const unsigned int mon0,
        const unsigned int day, const unsigned int hour,
        const unsigned int min, const unsigned int sec)
 {
         unsigned int mon = mon0, year = year0;
 
         /* 1..12 -> 11,12,1..10 */
         if (0 >= (int) (mon -= 2)) {
                 mon += 12;      /* Puts Feb last since it has leap day */
                 year -= 1;
         }
 
         return ((((unsigned long)
                   (year/4 - year/100 + year/400 + 367*mon/12 + day) +
                   year*365 - 719499
             )*24 + hour /* now have hours */
           )*60 + min /* now have minutes */
         )*60 + sec; /* finally seconds */
 }
 
 EXPORT_SYMBOL(mktime);
 
 /**
  * set_normalized_timespec - set timespec sec and nsec parts and normalize
  *
  * @ts:         pointer to timespec variable to be set
  * @sec:        seconds to set
  * @nsec:       nanoseconds to set
  *
  * Set seconds and nanoseconds field of a timespec variable and
  * normalize to the timespec storage format
  *
  * Note: The tv_nsec part is always in the range of
  *      0 <= tv_nsec < NSEC_PER_SEC
  * For negative values only the tv_sec field is negative !
  */
 void set_normalized_timespec(struct timespec *ts, time_t sec, s64 nsec)
 {
         while (nsec >= NSEC_PER_SEC) {
                 /*
                  * The following asm() prevents the compiler from
                  * optimising this loop into a modulo operation. See
                  * also __iter_div_u64_rem() in include/linux/time.h
                  */
                 asm("" : "+rm"(nsec));
                 nsec -= NSEC_PER_SEC;
                 ++sec;
         }
         while (nsec < 0) {
                 asm("" : "+rm"(nsec));
                 nsec += NSEC_PER_SEC;
                 --sec;
         }
         ts->tv_sec = sec;
         ts->tv_nsec = nsec;
 }
 EXPORT_SYMBOL(set_normalized_timespec);
 
 /**
  * ns_to_timespec - Convert nanoseconds to timespec
  * @nsec:       the nanoseconds value to be converted
  *
  * Returns the timespec representation of the nsec parameter.
  */
 struct timespec ns_to_timespec(const s64 nsec)
 {
         struct timespec ts;
         s32 rem;
 
         if (!nsec)
                 return (struct timespec) {0, 0};
 
         ts.tv_sec = div_s64_rem(nsec, NSEC_PER_SEC, &rem);
         if (unlikely(rem < 0)) {
                 ts.tv_sec--;
                 rem += NSEC_PER_SEC;
         }
         ts.tv_nsec = rem;
 
         return ts;
 }
 EXPORT_SYMBOL(ns_to_timespec);
 
 /**
  * ns_to_timeval - Convert nanoseconds to timeval
  * @nsec:       the nanoseconds value to be converted
  *
  * Returns the timeval representation of the nsec parameter.
  */
 struct timeval ns_to_timeval(const s64 nsec)
 {
         struct timespec ts = ns_to_timespec(nsec);
         struct timeval tv;
 
         tv.tv_sec = ts.tv_sec;
         tv.tv_usec = (suseconds_t) ts.tv_nsec / 1000;
 
         return tv;
 }
 EXPORT_SYMBOL(ns_to_timeval);
 
 /*
  * When we convert to jiffies then we interpret incoming values
  * the following way:
  *
  * - negative values mean 'infinite timeout' (MAX_JIFFY_OFFSET)
  *
  * - 'too large' values [that would result in larger than
  *   MAX_JIFFY_OFFSET values] mean 'infinite timeout' too.
  *
  * - all other values are converted to jiffies by either multiplying
  *   the input value by a factor or dividing it with a factor
  *
  * We must also be careful about 32-bit overflows.
  */
 unsigned long msecs_to_jiffies(const unsigned int m)
 {
         /*
          * Negative value, means infinite timeout:
          */
         if ((int)m < 0)
                 return MAX_JIFFY_OFFSET;
 
 #if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ)
         /*
          * HZ is equal to or smaller than 1000, and 1000 is a nice
          * round multiple of HZ, divide with the factor between them,
          * but round upwards:
          */
         return (m + (MSEC_PER_SEC / HZ) - 1) / (MSEC_PER_SEC / HZ);
 #elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC)
         /*
          * HZ is larger than 1000, and HZ is a nice round multiple of
          * 1000 - simply multiply with the factor between them.
          *
          * But first make sure the multiplication result cannot
          * overflow:
          */
         if (m > jiffies_to_msecs(MAX_JIFFY_OFFSET))
                 return MAX_JIFFY_OFFSET;
 
         return m * (HZ / MSEC_PER_SEC);
 #else
         /*
          * Generic case - multiply, round and divide. But first
          * check that if we are doing a net multiplication, that
          * we wouldn't overflow:
          */
         if (HZ > MSEC_PER_SEC && m > jiffies_to_msecs(MAX_JIFFY_OFFSET))
                 return MAX_JIFFY_OFFSET;
 
         return (MSEC_TO_HZ_MUL32 * m + MSEC_TO_HZ_ADJ32)
                 >> MSEC_TO_HZ_SHR32;
 #endif
 }
 EXPORT_SYMBOL(msecs_to_jiffies);
 
 unsigned long usecs_to_jiffies(const unsigned int u)
 {
         if (u > jiffies_to_usecs(MAX_JIFFY_OFFSET))
                 return MAX_JIFFY_OFFSET;
 #if HZ <= USEC_PER_SEC && !(USEC_PER_SEC % HZ)
         return (u + (USEC_PER_SEC / HZ) - 1) / (USEC_PER_SEC / HZ);
 #elif HZ > USEC_PER_SEC && !(HZ % USEC_PER_SEC)
         return u * (HZ / USEC_PER_SEC);
 #else
         return (USEC_TO_HZ_MUL32 * u + USEC_TO_HZ_ADJ32)
                 >> USEC_TO_HZ_SHR32;
 #endif
 }
 EXPORT_SYMBOL(usecs_to_jiffies);
 
 /*
  * The TICK_NSEC - 1 rounds up the value to the next resolution.  Note
  * that a remainder subtract here would not do the right thing as the
  * resolution values don't fall on second boundries.  I.e. the line:
  * nsec -= nsec % TICK_NSEC; is NOT a correct resolution rounding.
  *
  * Rather, we just shift the bits off the right.
  *
  * The >> (NSEC_JIFFIE_SC - SEC_JIFFIE_SC) converts the scaled nsec
  * value to a scaled second value.
  */
 unsigned long
 timespec_to_jiffies(const struct timespec *value)
 {
         unsigned long sec = value->tv_sec;
         long nsec = value->tv_nsec + TICK_NSEC - 1;
 
         if (sec >= MAX_SEC_IN_JIFFIES){
                 sec = MAX_SEC_IN_JIFFIES;
                 nsec = 0;
         }
         return (((u64)sec * SEC_CONVERSION) +
                 (((u64)nsec * NSEC_CONVERSION) >>
                  (NSEC_JIFFIE_SC - SEC_JIFFIE_SC))) >> SEC_JIFFIE_SC;
 
 }
 EXPORT_SYMBOL(timespec_to_jiffies);
 
 void
 jiffies_to_timespec(const unsigned long jiffies, struct timespec *value)
 {
         /*
          * Convert jiffies to nanoseconds and separate with
          * one divide.
          */
         u32 rem;
         value->tv_sec = div_u64_rem((u64)jiffies * TICK_NSEC,
                                     NSEC_PER_SEC, &rem);
         value->tv_nsec = rem;
 }
 EXPORT_SYMBOL(jiffies_to_timespec);
 
 /* Same for "timeval"
  *
  * Well, almost.  The problem here is that the real system resolution is
  * in nanoseconds and the value being converted is in micro seconds.
  * Also for some machines (those that use HZ = 1024, in-particular),
  * there is a LARGE error in the tick size in microseconds.
 
  * The solution we use is to do the rounding AFTER we convert the
  * microsecond part.  Thus the USEC_ROUND, the bits to be shifted off.
  * Instruction wise, this should cost only an additional add with carry
  * instruction above the way it was done above.
  */
 unsigned long
 timeval_to_jiffies(const struct timeval *value)
 {
         unsigned long sec = value->tv_sec;
         long usec = value->tv_usec;
 
         if (sec >= MAX_SEC_IN_JIFFIES){
                 sec = MAX_SEC_IN_JIFFIES;
                 usec = 0;
         }
         return (((u64)sec * SEC_CONVERSION) +
                 (((u64)usec * USEC_CONVERSION + USEC_ROUND) >>
                  (USEC_JIFFIE_SC - SEC_JIFFIE_SC))) >> SEC_JIFFIE_SC;
 }
 EXPORT_SYMBOL(timeval_to_jiffies);
 
 void jiffies_to_timeval(const unsigned long jiffies, struct timeval *value)
 {
         /*
          * Convert jiffies to nanoseconds and separate with
          * one divide.
          */
         u32 rem;
 
         value->tv_sec = div_u64_rem((u64)jiffies * TICK_NSEC,
                                     NSEC_PER_SEC, &rem);
         value->tv_usec = rem / NSEC_PER_USEC;
 }
 EXPORT_SYMBOL(jiffies_to_timeval);
 
 /*
  * Convert jiffies/jiffies_64 to clock_t and back.
  */
 clock_t jiffies_to_clock_t(long x)
 {
 #if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0
 # if HZ < USER_HZ
         return x * (USER_HZ / HZ);
 # else
         return x / (HZ / USER_HZ);
 # endif
 #else
         return div_u64((u64)x * TICK_NSEC, NSEC_PER_SEC / USER_HZ);
 #endif
 }
 EXPORT_SYMBOL(jiffies_to_clock_t);
 
 unsigned long clock_t_to_jiffies(unsigned long x)
 {
 #if (HZ % USER_HZ)==0
         if (x >= ~0UL / (HZ / USER_HZ))
                 return ~0UL;
         return x * (HZ / USER_HZ);
 #else
         /* Don't worry about loss of precision here .. */
         if (x >= ~0UL / HZ * USER_HZ)
                 return ~0UL;
 
         /* .. but do try to contain it here */
         return div_u64((u64)x * HZ, USER_HZ);
 #endif
 }
 EXPORT_SYMBOL(clock_t_to_jiffies);
 
 u64 jiffies_64_to_clock_t(u64 x)
 {
 #if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0
 # if HZ < USER_HZ
         x = div_u64(x * USER_HZ, HZ);
 # elif HZ > USER_HZ
         x = div_u64(x, HZ / USER_HZ);
 # else
         /* Nothing to do */
 # endif
 #else
         /*
          * There are better ways that don't overflow early,
          * but even this doesn't overflow in hundreds of years
          * in 64 bits, so..
          */
         x = div_u64(x * TICK_NSEC, (NSEC_PER_SEC / USER_HZ));
 #endif
         return x;
 }
 EXPORT_SYMBOL(jiffies_64_to_clock_t);
 
 u64 nsec_to_clock_t(u64 x)
 {
 #if (NSEC_PER_SEC % USER_HZ) == 0
         return div_u64(x, NSEC_PER_SEC / USER_HZ);
 #elif (USER_HZ % 512) == 0
         return div_u64(x * USER_HZ / 512, NSEC_PER_SEC / 512);
 #else
         /*
          * max relative error 5.7e-8 (1.8s per year) for USER_HZ <= 1024,
          * overflow after 64.99 years.
          * exact for HZ=60, 72, 90, 120, 144, 180, 300, 600, 900, ...
          */
         return div_u64(x * 9, (9ull * NSEC_PER_SEC + (USER_HZ / 2)) / USER_HZ);
 #endif
 }
 
 /**
  * nsecs_to_jiffies - Convert nsecs in u64 to jiffies
  *
  * @n:  nsecs in u64
  *
  * Unlike {m,u}secs_to_jiffies, type of input is not unsigned int but u64.
  * And this doesn't return MAX_JIFFY_OFFSET since this function is designed
  * for scheduler, not for use in device drivers to calculate timeout value.
  *
  * note:
  *   NSEC_PER_SEC = 10^9 = (5^9 * 2^9) = (1953125 * 512)
  *   ULLONG_MAX ns = 18446744073.709551615 secs = about 584 years
  */
 unsigned long nsecs_to_jiffies(u64 n)
 {
 #if (NSEC_PER_SEC % HZ) == 0
         /* Common case, HZ = 100, 128, 200, 250, 256, 500, 512, 1000 etc. */
         return div_u64(n, NSEC_PER_SEC / HZ);
 #elif (HZ % 512) == 0
         /* overflow after 292 years if HZ = 1024 */
         return div_u64(n * HZ / 512, NSEC_PER_SEC / 512);
 #else
         /*
          * Generic case - optimized for cases where HZ is a multiple of 3.
          * overflow after 64.99 years, exact for HZ = 60, 72, 90, 120 etc.
          */
         return div_u64(n * 9, (9ull * NSEC_PER_SEC + HZ / 2) / HZ);
 #endif
 }
 
 #if (BITS_PER_LONG < 64)
 u64 get_jiffies_64(void)
 {
         unsigned long seq;
         u64 ret;
 
         do {
                 seq = read_seqbegin(&xtime_lock);
                 ret = jiffies_64;
         } while (read_seqretry(&xtime_lock, seq));
         return ret;
 }
 EXPORT_SYMBOL(get_jiffies_64);
 #endif
 
 EXPORT_SYMBOL(jiffies);
 
 /*
  * Add two timespec values and do a safety check for overflow.
  * It's assumed that both values are valid (>= 0)
  */
 struct timespec timespec_add_safe(const struct timespec lhs,
                                   const struct timespec rhs)
 {
         struct timespec res;
 
         set_normalized_timespec(&res, lhs.tv_sec + rhs.tv_sec,
                                 lhs.tv_nsec + rhs.tv_nsec);
 
         if (res.tv_sec < lhs.tv_sec || res.tv_sec < rhs.tv_sec)
                 res.tv_sec = TIME_T_MAX;
 
         return res;
 }
 

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