user/sven/linux.git/kernel/time/timekeeping.c, branch v4.17.13

Revert: Unify CLOCK_MONOTONIC and CLOCK_BOOTTIME

2018-04-26T12:53:32Z

Revert commits 92af4dcb4e1c ("tracing: Unify the "boot" and "mono" tracing clocks") 127bfa5f4342 ("hrtimer: Unify MONOTONIC and BOOTTIME clock behavior") 7250a4047aa6 ("posix-timers: Unify MONOTONIC and BOOTTIME clock behavior") d6c7270e913d ("timekeeping: Remove boot time specific code") f2d6fdbfd238 ("Input: Evdev - unify MONOTONIC and BOOTTIME clock behavior") d6ed449afdb3 ("timekeeping: Make the MONOTONIC clock behave like the BOOTTIME clock") 72199320d49d ("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 Reported-by: Genki Sky , Reported-by: Pavel Machek Signed-off-by: Thomas Gleixner Cc: Dmitry Torokhov Cc: John Stultz Cc: Jonathan Corbet Cc: Kevin Easton Cc: Linus Torvalds Cc: Mark Salyzyn Cc: Michael Kerrisk Cc: Peter Zijlstra Cc: Petr Mladek Cc: Prarit Bhargava Cc: Sergey Senozhatsky Cc: Steven Rostedt

timekeeping: Remove __current_kernel_time()

2018-04-17T15:18:05Z

The __current_kernel_time() function based on 'struct timespec' is no longer recommended for new code, and the only user of this function has been replaced by commit 6909e29fdefb ("kdb: use __ktime_get_real_seconds instead of __current_kernel_time"). Remove the obsolete interface. Signed-off-by: Baolin Wang Signed-off-by: Thomas Gleixner Cc: arnd@arndb.de Cc: sboyd@kernel.org Cc: broonie@kernel.org Cc: john.stultz@linaro.org Link: https://lkml.kernel.org/r/1a9dbea7ee2cda7efe9ed330874075cf17fdbff6.1523596316.git.baolin.wang@linaro.org

hrtimer: Unify MONOTONIC and BOOTTIME clock behavior

2018-03-13T06:34:23Z

Now that th MONOTONIC and BOOTTIME clocks are indentical remove all the special casing. The user space visible interfaces still support both clocks, but their behavior is identical. Signed-off-by: Thomas Gleixner Cc: Dmitry Torokhov Cc: John Stultz Cc: Jonathan Corbet Cc: Kevin Easton Cc: Linus Torvalds Cc: Mark Salyzyn Cc: Michael Kerrisk Cc: Peter Zijlstra Cc: Petr Mladek Cc: Prarit Bhargava Cc: Sergey Senozhatsky Cc: Steven Rostedt Link: http://lkml.kernel.org/r/20180301165150.410218515@linutronix.de Signed-off-by: Ingo Molnar

timekeeping: Remove boot time specific code

2018-03-13T06:34:22Z

Now that the MONOTONIC and BOOTTIME clocks are the same, remove all the special handling from timekeeping. Keep wrappers for the existing users of the *boot* timekeeper interfaces. Signed-off-by: Thomas Gleixner Cc: Dmitry Torokhov Cc: John Stultz Cc: Jonathan Corbet Cc: Kevin Easton Cc: Linus Torvalds Cc: Mark Salyzyn Cc: Michael Kerrisk Cc: Peter Zijlstra Cc: Petr Mladek Cc: Prarit Bhargava Cc: Sergey Senozhatsky Cc: Steven Rostedt Link: http://lkml.kernel.org/r/20180301165150.236279497@linutronix.de Signed-off-by: Ingo Molnar

timekeeping: Make the MONOTONIC clock behave like the BOOTTIME clock

2018-03-13T06:34:22Z

The MONOTONIC clock is not fast forwarded by the time spent in suspend on resume. This is only done for the BOOTTIME clock. The reason why the MONOTONIC clock is not forwarded is historical: the original Linux implementation was using jiffies as a base for the MONOTONIC clock and jiffies have never been advanced after resume. At some point when timekeeping was unified in the core code, the MONONOTIC clock was advanced after resume which also advanced jiffies causing interesting side effects. As a consequence the the MONOTONIC clock forwarding was disabled again and the BOOTTIME clock was introduced, which allows to read time since boot. Back then it was not possible to completely distangle the MONOTONIC clock and jiffies because there were still interfaces which exposed the MONOTONIC clock behaviour based on the timer wheel and therefore jiffies. As of today none of the MONOTONIC clock facilities depends on jiffies anymore so the forwarding can be done seperately. This is achieved by forwarding the variables which are used for the jiffies update after resume before the tick is restarted, In timekeeping resume, the change is rather simple. Instead of updating the offset between the MONOTONIC clock and the REALTIME/BOOTTIME clocks, advance the time keeper base for the MONOTONIC and the MONOTONIC_RAW clocks by the time spent in suspend. The MONOTONIC clock is now the same as the BOOTTIME clock and the offset between the REALTIME and the MONOTONIC clocks is the same as before suspend. There might be side effects in applications, which rely on the (unfortunately) well documented behaviour of the MONOTONIC clock, but the downsides of the existing behaviour are probably worse. There is one obvious issue. Up to now it was possible to retrieve the time spent in suspend by observing the delta between the MONOTONIC clock and the BOOTTIME clock. This is not longer available, but the previously introduced mechanism to read the active non-suspended monotonic time can mitigate that in a detectable fashion. Signed-off-by: Thomas Gleixner Cc: Andrew Morton Cc: Dmitry Torokhov Cc: John Stultz Cc: Jonathan Corbet Cc: Kevin Easton Cc: Linus Torvalds Cc: Mark Salyzyn Cc: Michael Kerrisk Cc: Peter Zijlstra Cc: Petr Mladek Cc: Prarit Bhargava Cc: Sergey Senozhatsky Cc: Steven Rostedt Link: http://lkml.kernel.org/r/20180301165150.062975504@linutronix.de Signed-off-by: Ingo Molnar

timekeeping: Add the new CLOCK_MONOTONIC_ACTIVE clock

2018-03-13T06:34:21Z

The planned change to unify the behaviour of the MONOTONIC and BOOTTIME clocks vs. suspend removes the ability to retrieve the active non-suspended time of a system. Provide a new CLOCK_MONOTONIC_ACTIVE clock which returns the active non-suspended time of the system via clock_gettime(). This preserves the old behaviour of CLOCK_MONOTONIC before the BOOTTIME/MONOTONIC unification. This new clock also allows applications to detect programmatically that the MONOTONIC and BOOTTIME clocks are identical. Signed-off-by: Thomas Gleixner Cc: Dmitry Torokhov Cc: John Stultz Cc: Jonathan Corbet Cc: Kevin Easton Cc: Linus Torvalds Cc: Mark Salyzyn Cc: Michael Kerrisk Cc: Peter Zijlstra Cc: Petr Mladek Cc: Prarit Bhargava Cc: Sergey Senozhatsky Cc: Steven Rostedt Link: http://lkml.kernel.org/r/20180301165149.965235774@linutronix.de Signed-off-by: Ingo Molnar

timekeeping/ntp: Determine the multiplier directly from NTP tick length

2018-03-10T08:12:41Z

When the length of the NTP tick changes significantly, e.g. when an NTP/PTP application is correcting the initial offset of the clock, a large value may accumulate in the NTP error before the multiplier converges to the correct value. It may then take a very long time (hours or even days) before the error is corrected. This causes the clock to have an unstable frequency offset, which has a negative impact on the stability of synchronization with precise time sources (e.g. NTP/PTP using hardware timestamping or the PTP KVM clock). Use division to determine the correct multiplier directly from the NTP tick length and replace the iterative approach. This removes the last major source of the NTP error. The only remaining source is now limited resolution of the multiplier, which is corrected by adding 1 to the multiplier when the system clock is behind the NTP time. Signed-off-by: Miroslav Lichvar Signed-off-by: John Stultz Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Prarit Bhargava Cc: Richard Cochran Cc: Stephen Boyd Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1520620971-9567-3-git-send-email-john.stultz@linaro.org Signed-off-by: Ingo Molnar

timekeeping/ntp: Don't align NTP frequency adjustments to ticks

2018-03-10T08:12:41Z

When the timekeeping multiplier is changed, the NTP error is updated to correct the clock for the delay between the tick and the update of the clock. This error is corrected in later updates and the clock appears as if the frequency was changed exactly on the tick. Remove this correction to keep the point where the frequency is effectively changed at the time of the update. This removes a major source of the NTP error. Signed-off-by: Miroslav Lichvar Signed-off-by: John Stultz Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Prarit Bhargava Cc: Richard Cochran Cc: Stephen Boyd Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1520620971-9567-2-git-send-email-john.stultz@linaro.org Signed-off-by: Ingo Molnar

timekeeping: Remove CONFIG_GENERIC_TIME_VSYSCALL_OLD

2017-11-14T10:20:25Z

As of d4d1fc61eb38f (ia64: Update fsyscall gettime to use modern vsyscall_update)the last user of CONFIG_GENERIC_TIME_VSYSCALL_OLD have been updated, the legacy support for old-style vsyscall implementations can be removed from the timekeeping code. (Thanks again to Tony Luck for helping remove the last user!) [jstultz: Commit message rework] Signed-off-by: Miroslav Lichvar Signed-off-by: John Stultz Signed-off-by: Thomas Gleixner Cc: Prarit Bhargava Cc: Tony Luck Cc: Richard Cochran Cc: Stephen Boyd Link: https://lkml.kernel.org/r/1510613491-16695-1-git-send-email-john.stultz@linaro.org

pstore: Use ktime_get_real_fast_ns() instead of __getnstimeofday()

2017-11-12T14:05:52Z

__getnstimeofday() is a rather odd interface, with a number of quirks: - The caller may come from NMI context, but the implementation is not NMI safe, one way to get there from NMI is NMI handler: something bad panic() kmsg_dump() pstore_dump() pstore_record_init() __getnstimeofday() - The calling conventions are different from any other timekeeping functions, to deal with returning an error code during suspended timekeeping. Address the above issues by using a completely different method to get the time: ktime_get_real_fast_ns() is NMI safe and has a reasonable behavior when timekeeping is suspended: it returns the time at which it got suspended. As Thomas Gleixner explained, this is safe, as ktime_get_real_fast_ns() does not call into the clocksource driver that might be suspended. The result can easily be transformed into a timespec structure. Since ktime_get_real_fast_ns() was not exported to modules, add the export. The pstore behavior for the suspended case changes slightly, as it now stores the timestamp at which timekeeping was suspended instead of storing a zero timestamp. This change is not addressing y2038-safety, that's subject to a more complex follow up patch. Signed-off-by: Arnd Bergmann Signed-off-by: Thomas Gleixner Acked-by: Kees Cook Cc: Tony Luck Cc: Anton Vorontsov Cc: Stephen Boyd Cc: John Stultz Cc: Colin Cross Link: https://lkml.kernel.org/r/20171110152530.1926955-1-arnd@arndb.de