@@ -1283,15 +1283,15 @@ void get_xtime_and_monotonic_and_sleep_offset(struct timespec *xtim,
*/
ktime_t ktime_get_update_offsets(ktime_t *offs_real, ktime_t *offs_boot)
{
- ktime_t now;
unsigned int seq;
u64 secs, nsecs;
do {
seq = read_seqbegin(&timekeeper.lock);
-
- secs = timekeeper.xtime.tv_sec;
- nsecs = timekeeper.xtime.tv_nsec;
+ secs = timekeeper.xtime.tv_sec +
+ timekeeper.wall_to_monotonic.tv_sec;
+ nsecs = timekeeper.xtime.tv_nsec +
+ timekeeper.wall_to_monotonic.tv_nsec;
nsecs += timekeeping_get_ns();
/* If arch requires, add in gettimeoffset() */
nsecs += arch_gettimeoffset();
@@ -1300,9 +1300,7 @@ ktime_t ktime_get_update_offsets(ktime_t *offs_real, ktime_t *offs_boot)
*offs_boot = timekeeper.offs_boot;
} while (read_seqretry(&timekeeper.lock, seq));
- now = ktime_add_ns(ktime_set(secs, 0), nsecs);
- now = ktime_sub(now, *offs_real);
- return now;
+ return ktime_add_ns(ktime_set(secs, 0), nsecs);
}
#endif
There's currently a slight difference in ktime_get_update_offsets() vs ktime_get() which can result in boot time crashes when booting with insane CMOS clock values larger then ~2264. ktime_get() does basically the following: return timespec_to_ktime(timespec_add(xtime, wall_to_monotonic)) Where as ktime_get_update_offsets does approximately: return ktime_sub(timespec_to_ktime(xtime), realtime_offset); The problem is, at boot we set xtime = year 8200 and wall_to_monotonic = year -8200, ktime_get adds both values, mostly nulling the difference out (leaving only how long the system has been up), then converts that relatively small value to a ktime_t properly without losing any information. ktime_get_update_offsets however, since it converts xtime (again set to some value greater then year 8200), to a ktime, it gets clamped at KTIME_MAX, then we subtract realtime_offset, which is _also_ clamped at KTIME_MAX, resulting in us always returning almost[1] zero. This causes us to stop expiring timers. Now, one of the reasons Thomas and I changed the logic was that using the precalculated realtime_offset was slightly more efficient then re-adding xtime and wall_to_monotonic's components separately. But how valuable this unmeasured slight efficiency is vs extra robustness for crazy time values is questionable. So switch back to the ktime_get implementation for ktime_get_update_offsets Cc: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Zhouping Liu <zliu@redhat.com> Cc: CAI Qian <caiqian@redhat.com> Reported-by: CAI Qian <caiqian@redhat.com> Signed-off-by: John Stultz <john.stultz@linaro.org> --- kernel/time/timekeeping.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-)