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linux-next/include/linux/timekeeper_internal.h
Thomas Gleixner a3ed0e4393 Revert: Unify CLOCK_MONOTONIC and CLOCK_BOOTTIME
Revert commits

92af4dcb4e ("tracing: Unify the "boot" and "mono" tracing clocks")
127bfa5f43 ("hrtimer: Unify MONOTONIC and BOOTTIME clock behavior")
7250a4047a ("posix-timers: Unify MONOTONIC and BOOTTIME clock behavior")
d6c7270e91 ("timekeeping: Remove boot time specific code")
f2d6fdbfd2 ("Input: Evdev - unify MONOTONIC and BOOTTIME clock behavior")
d6ed449afd ("timekeeping: Make the MONOTONIC clock behave like the BOOTTIME clock")
72199320d4 ("timekeeping: Add the new CLOCK_MONOTONIC_ACTIVE clock")

As stated in the pull request for the unification of CLOCK_MONOTONIC and
CLOCK_BOOTTIME, it was clear that we might have to revert the change.

As reported by several folks systemd and other applications rely on the
documented behaviour of CLOCK_MONOTONIC on Linux and break with the above
changes. After resume daemons time out and other timeout related issues are
observed. Rafael compiled this list:

* systemd kills daemons on resume, after >WatchdogSec seconds
  of suspending (Genki Sky).  [Verified that that's because systemd uses
  CLOCK_MONOTONIC and expects it to not include the suspend time.]

* systemd-journald misbehaves after resume:
  systemd-journald[7266]: File /var/log/journal/016627c3c4784cd4812d4b7e96a34226/system.journal
corrupted or uncleanly shut down, renaming and replacing.
  (Mike Galbraith).

* NetworkManager reports "networking disabled" and networking is broken
  after resume 50% of the time (Pavel).  [May be because of systemd.]

* MATE desktop dims the display and starts the screensaver right after
  system resume (Pavel).

* Full system hang during resume (me).  [May be due to systemd or NM or both.]

That happens on debian and open suse systems.

It's sad, that these problems were neither catched in -next nor by those
folks who expressed interest in this change.

Reported-by: Rafael J. Wysocki <rjw@rjwysocki.net>
Reported-by: Genki Sky <sky@genki.is>,
Reported-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kevin Easton <kevin@guarana.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Salyzyn <salyzyn@android.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
2018-04-26 14:53:32 +02:00

152 lines
5.1 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
/*
* You SHOULD NOT be including this unless you're vsyscall
* handling code or timekeeping internal code!
*/
#ifndef _LINUX_TIMEKEEPER_INTERNAL_H
#define _LINUX_TIMEKEEPER_INTERNAL_H
#include <linux/clocksource.h>
#include <linux/jiffies.h>
#include <linux/time.h>
/**
* struct tk_read_base - base structure for timekeeping readout
* @clock: Current clocksource used for timekeeping.
* @mask: Bitmask for two's complement subtraction of non 64bit clocks
* @cycle_last: @clock cycle value at last update
* @mult: (NTP adjusted) multiplier for scaled math conversion
* @shift: Shift value for scaled math conversion
* @xtime_nsec: Shifted (fractional) nano seconds offset for readout
* @base: ktime_t (nanoseconds) base time for readout
* @base_real: Nanoseconds base value for clock REALTIME readout
*
* This struct has size 56 byte on 64 bit. Together with a seqcount it
* occupies a single 64byte cache line.
*
* The struct is separate from struct timekeeper as it is also used
* for a fast NMI safe accessors.
*
* @base_real is for the fast NMI safe accessor to allow reading clock
* realtime from any context.
*/
struct tk_read_base {
struct clocksource *clock;
u64 mask;
u64 cycle_last;
u32 mult;
u32 shift;
u64 xtime_nsec;
ktime_t base;
u64 base_real;
};
/**
* struct timekeeper - Structure holding internal timekeeping values.
* @tkr_mono: The readout base structure for CLOCK_MONOTONIC
* @tkr_raw: The readout base structure for CLOCK_MONOTONIC_RAW
* @xtime_sec: Current CLOCK_REALTIME time in seconds
* @ktime_sec: Current CLOCK_MONOTONIC time in seconds
* @wall_to_monotonic: CLOCK_REALTIME to CLOCK_MONOTONIC offset
* @offs_real: Offset clock monotonic -> clock realtime
* @offs_boot: Offset clock monotonic -> clock boottime
* @offs_tai: Offset clock monotonic -> clock tai
* @tai_offset: The current UTC to TAI offset in seconds
* @clock_was_set_seq: The sequence number of clock was set events
* @cs_was_changed_seq: The sequence number of clocksource change events
* @next_leap_ktime: CLOCK_MONOTONIC time value of a pending leap-second
* @raw_sec: CLOCK_MONOTONIC_RAW time in seconds
* @cycle_interval: Number of clock cycles in one NTP interval
* @xtime_interval: Number of clock shifted nano seconds in one NTP
* interval.
* @xtime_remainder: Shifted nano seconds left over when rounding
* @cycle_interval
* @raw_interval: Shifted raw nano seconds accumulated per NTP interval.
* @ntp_error: Difference between accumulated time and NTP time in ntp
* shifted nano seconds.
* @ntp_error_shift: Shift conversion between clock shifted nano seconds and
* ntp shifted nano seconds.
* @last_warning: Warning ratelimiter (DEBUG_TIMEKEEPING)
* @underflow_seen: Underflow warning flag (DEBUG_TIMEKEEPING)
* @overflow_seen: Overflow warning flag (DEBUG_TIMEKEEPING)
*
* Note: For timespec(64) based interfaces wall_to_monotonic is what
* we need to add to xtime (or xtime corrected for sub jiffie times)
* to get to monotonic time. Monotonic is pegged at zero at system
* boot time, so wall_to_monotonic will be negative, however, we will
* ALWAYS keep the tv_nsec part positive so we can use the usual
* normalization.
*
* wall_to_monotonic is moved after resume from suspend for the
* monotonic time not to jump. We need to add total_sleep_time to
* wall_to_monotonic to get the real boot based time offset.
*
* wall_to_monotonic is no longer the boot time, getboottime must be
* used instead.
*/
struct timekeeper {
struct tk_read_base tkr_mono;
struct tk_read_base tkr_raw;
u64 xtime_sec;
unsigned long ktime_sec;
struct timespec64 wall_to_monotonic;
ktime_t offs_real;
ktime_t offs_boot;
ktime_t offs_tai;
s32 tai_offset;
unsigned int clock_was_set_seq;
u8 cs_was_changed_seq;
ktime_t next_leap_ktime;
u64 raw_sec;
/* The following members are for timekeeping internal use */
u64 cycle_interval;
u64 xtime_interval;
s64 xtime_remainder;
u64 raw_interval;
/* The ntp_tick_length() value currently being used.
* This cached copy ensures we consistently apply the tick
* length for an entire tick, as ntp_tick_length may change
* mid-tick, and we don't want to apply that new value to
* the tick in progress.
*/
u64 ntp_tick;
/* Difference between accumulated time and NTP time in ntp
* shifted nano seconds. */
s64 ntp_error;
u32 ntp_error_shift;
u32 ntp_err_mult;
/* Flag used to avoid updating NTP twice with same second */
u32 skip_second_overflow;
#ifdef CONFIG_DEBUG_TIMEKEEPING
long last_warning;
/*
* These simple flag variables are managed
* without locks, which is racy, but they are
* ok since we don't really care about being
* super precise about how many events were
* seen, just that a problem was observed.
*/
int underflow_seen;
int overflow_seen;
#endif
};
#ifdef CONFIG_GENERIC_TIME_VSYSCALL
extern void update_vsyscall(struct timekeeper *tk);
extern void update_vsyscall_tz(void);
#else
static inline void update_vsyscall(struct timekeeper *tk)
{
}
static inline void update_vsyscall_tz(void)
{
}
#endif
#endif /* _LINUX_TIMEKEEPER_INTERNAL_H */