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2015-06-12ntp: Do leapsecond adjustment in adjtimex read pathJohn Stultz
Since the leapsecond is applied at tick-time, this means there is a small window of time at the start of a leap-second where we cross into the next second before applying the leap. This patch modified adjtimex so that the leap-second is applied on the second edge. Providing more correct leapsecond behavior. This does make it so that adjtimex()'s returned time values can be inconsistent with time values read from gettimeofday() or clock_gettime(CLOCK_REALTIME,...) for a brief period of one tick at the leapsecond. However, those other interfaces do not provide the TIME_OOP time_state return that adjtimex() provides, which allows the leapsecond to be properly represented. They instead only see a time discontinuity, and cannot tell the first 23:59:59 from the repeated 23:59:59 leap second. This seems like a reasonable tradeoff given clock_gettime() / gettimeofday() cannot properly represent a leapsecond, and users likely care more about performance, while folks who are using adjtimex() more likely care about leap-second correctness. Signed-off-by: John Stultz <john.stultz@linaro.org> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Daniel Bristot de Oliveira <bristot@redhat.com> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Jan Kara <jack@suse.cz> Cc: Jiri Bohac <jbohac@suse.cz> Cc: Ingo Molnar <mingo@kernel.org> Link: http://lkml.kernel.org/r/1434063297-28657-5-git-send-email-john.stultz@linaro.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-06-12time: Prevent early expiry of hrtimers[CLOCK_REALTIME] at the leap second edgeJohn Stultz
Currently, leapsecond adjustments are done at tick time. As a result, the leapsecond was applied at the first timer tick *after* the leapsecond (~1-10ms late depending on HZ), rather then exactly on the second edge. This was in part historical from back when we were always tick based, but correcting this since has been avoided since it adds extra conditional checks in the gettime fastpath, which has performance overhead. However, it was recently pointed out that ABS_TIME CLOCK_REALTIME timers set for right after the leapsecond could fire a second early, since some timers may be expired before we trigger the timekeeping timer, which then applies the leapsecond. This isn't quite as bad as it sounds, since behaviorally it is similar to what is possible w/ ntpd made leapsecond adjustments done w/o using the kernel discipline. Where due to latencies, timers may fire just prior to the settimeofday call. (Also, one should note that all applications using CLOCK_REALTIME timers should always be careful, since they are prone to quirks from settimeofday() disturbances.) However, the purpose of having the kernel do the leap adjustment is to avoid such latencies, so I think this is worth fixing. So in order to properly keep those timers from firing a second early, this patch modifies the ntp and timekeeping logic so that we keep enough state so that the update_base_offsets_now accessor, which provides the hrtimer core the current time, can check and apply the leapsecond adjustment on the second edge. This prevents the hrtimer core from expiring timers too early. This patch does not modify any other time read path, so no additional overhead is incurred. However, this also means that the leap-second continues to be applied at tick time for all other read-paths. Apologies to Richard Cochran, who pushed for similar changes years ago, which I resisted due to the concerns about the performance overhead. While I suspect this isn't extremely critical, folks who care about strict leap-second correctness will likely want to watch this. Potentially a -stable candidate eventually. Originally-suggested-by: Richard Cochran <richardcochran@gmail.com> Reported-by: Daniel Bristot de Oliveira <bristot@redhat.com> Reported-by: Prarit Bhargava <prarit@redhat.com> Signed-off-by: John Stultz <john.stultz@linaro.org> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Jan Kara <jack@suse.cz> Cc: Jiri Bohac <jbohac@suse.cz> Cc: Shuah Khan <shuahkh@osg.samsung.com> Cc: Ingo Molnar <mingo@kernel.org> Link: http://lkml.kernel.org/r/1434063297-28657-4-git-send-email-john.stultz@linaro.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-06-12ntp: Introduce and use SECS_PER_DAY macro instead of 86400John Stultz
Currently the leapsecond logic uses what looks like magic values. Improve this by defining SECS_PER_DAY and using that macro to make the logic more clear. Signed-off-by: John Stultz <john.stultz@linaro.org> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Daniel Bristot de Oliveira <bristot@redhat.com> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Jan Kara <jack@suse.cz> Cc: Jiri Bohac <jbohac@suse.cz> Cc: Ingo Molnar <mingo@kernel.org> Link: http://lkml.kernel.org/r/1434063297-28657-3-git-send-email-john.stultz@linaro.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-04-03time: Add y2038 safe update_persistent_clock64()Xunlei Pang
As part of addressing in-kernel y2038 issues, this patch adds update_persistent_clock64() and replaces all the call sites of update_persistent_clock() with this function. This is a __weak implementation, which simply calls the existing y2038 unsafe update_persistent_clock(). This allows architecture specific implementations to be converted independently, and eventually y2038-unsafe update_persistent_clock() can be removed after all its architecture specific implementations have been converted to update_persistent_clock64(). Suggested-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Xunlei Pang <pang.xunlei@linaro.org> Signed-off-by: John Stultz <john.stultz@linaro.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1427945681-29972-4-git-send-email-john.stultz@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-04-01tick: Move clocksource related stuff to timekeeping.hThomas Gleixner
Move clocksource related stuff to timekeeping.h and remove the pointless include from ntp.c Signed-off-by: Thomas Gleixner <tglx@linutronix.de> [ rjw: Subject ] Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/2714218.nM5AEfAHj0@vostro.rjw.lan Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-02-18ntp: Fixup adjtimex freq validation on 32-bit systemsJohn Stultz
Additional validation of adjtimex freq values to avoid potential multiplication overflows were added in commit 5e5aeb4367b (time: adjtimex: Validate the ADJ_FREQUENCY values) Unfortunately the patch used LONG_MAX/MIN instead of LLONG_MAX/MIN, which was fine on 64-bit systems, but being much smaller on 32-bit systems caused false positives resulting in most direct frequency adjustments to fail w/ EINVAL. ntpd only does direct frequency adjustments at startup, so the issue was not as easily observed there, but other time sync applications like ptpd and chrony were more effected by the bug. See bugs: https://bugzilla.kernel.org/show_bug.cgi?id=92481 https://bugzilla.redhat.com/show_bug.cgi?id=1188074 This patch changes the checks to use LLONG_MAX for clarity, and additionally the checks are disabled on 32-bit systems since LLONG_MAX/PPM_SCALE is always larger then the 32-bit long freq value, so multiplication overflows aren't possible there. Reported-by: Josh Boyer <jwboyer@fedoraproject.org> Reported-by: George Joseph <george.joseph@fairview5.com> Tested-by: George Joseph <george.joseph@fairview5.com> Signed-off-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: <stable@vger.kernel.org> # v3.19+ Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Sasha Levin <sasha.levin@oracle.com> Link: http://lkml.kernel.org/r/1423553436-29747-1-git-send-email-john.stultz@linaro.org [ Prettified the changelog and the comments a bit. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-02-09Merge branch 'timers-core-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull timer updates from Ingo Molnar: "The main changes in this cycle were: - rework hrtimer expiry calculation in hrtimer_interrupt(): the previous code had a subtle bug where expiry caching would miss an expiry, resulting in occasional bogus (late) expiry of hrtimers. - continuing Y2038 fixes - ktime division optimization - misc smaller fixes and cleanups" * 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: hrtimer: Make __hrtimer_get_next_event() static rtc: Convert rtc_set_ntp_time() to use timespec64 rtc: Remove redundant rtc_valid_tm() from rtc_hctosys() rtc: Modify rtc_hctosys() to address y2038 issues rtc: Update rtc-dev to use y2038-safe time interfaces rtc: Update interface.c to use y2038-safe time interfaces time: Expose get_monotonic_boottime64 for in-kernel use time: Expose getboottime64 for in-kernel uses ktime: Optimize ktime_divns for constant divisors hrtimer: Prevent stale expiry time in hrtimer_interrupt() ktime.h: Introduce ktime_ms_delta
2015-01-23rtc: Convert rtc_set_ntp_time() to use timespec64Xunlei Pang
rtc_set_ntp_time() uses timespec which is y2038-unsafe, so modify to use timespec64 which is y2038-safe, then replace rtc_time_to_tm() with rtc_time64_to_tm(). Also adjust all its call sites(only NTP uses it) accordingly. Cc: pang.xunlei <pang.xunlei@linaro.org> Cc: Arnd Bergmann <arnd.bergmann@linaro.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Signed-off-by: Xunlei Pang <pang.xunlei@linaro.org> Signed-off-by: John Stultz <john.stultz@linaro.org>
2015-01-07time: adjtimex: Validate the ADJ_FREQUENCY valuesSasha Levin
Verify that the frequency value from userspace is valid and makes sense. Unverified values can cause overflows later on. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: stable <stable@vger.kernel.org> Signed-off-by: Sasha Levin <sasha.levin@oracle.com> [jstultz: Fix up bug for negative values and drop redunent cap check] Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeping: Provide timespec64 based interfacesThomas Gleixner
To convert callers of the core code to timespec64 we need to provide the proper interfaces. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeping: Convert timekeeping core to use timespec64sJohn Stultz
Convert the core timekeeping logic to use timespec64s. This moves the 2038 issues out of the core logic and into all of the accessor functions. Future changes will need to push the timespec64s out to all timekeeping users, but that can be done interface by interface. Signed-off-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-06-04Merge branch 'akpm' (patchbomb from Andrew) into nextLinus Torvalds
Merge misc updates from Andrew Morton: - a few fixes for 3.16. Cc'ed to stable so they'll get there somehow. - various misc fixes and cleanups - most of the ocfs2 queue. Review is slow... - most of MM. The MM queue is pretty huge this time, but not much in the way of feature work. - some tweaks under kernel/ - printk maintenance work - updates to lib/ - checkpatch updates - tweaks to init/ * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (276 commits) fs/autofs4/dev-ioctl.c: add __init to autofs_dev_ioctl_init fs/ncpfs/getopt.c: replace simple_strtoul by kstrtoul init/main.c: remove an ifdef kthreads: kill CLONE_KERNEL, change kernel_thread(kernel_init) to avoid CLONE_SIGHAND init/main.c: add initcall_blacklist kernel parameter init/main.c: don't use pr_debug() fs/binfmt_flat.c: make old_reloc() static fs/binfmt_elf.c: fix bool assignements fs/efs: convert printk(KERN_DEBUG to pr_debug fs/efs: add pr_fmt / use __func__ fs/efs: convert printk to pr_foo() scripts/checkpatch.pl: device_initcall is not the only __initcall substitute checkpatch: check stable email address checkpatch: warn on unnecessary void function return statements checkpatch: prefer kstrto<foo> to sscanf(buf, "%<lhuidx>", &bar); checkpatch: add warning for kmalloc/kzalloc with multiply checkpatch: warn on #defines ending in semicolon checkpatch: make --strict a default for files in drivers/net and net/ checkpatch: always warn on missing blank line after variable declaration block checkpatch: fix wildcard DT compatible string checking ...
2014-06-04timekeeping: use printk_deferred when holding timekeeping seqlockJohn Stultz
Jiri Bohac pointed out that there are rare but potential deadlock possibilities when calling printk while holding the timekeeping seqlock. This is due to printk() triggering console sem wakeup, which can cause scheduling code to trigger hrtimers which may try to read the time. Specifically, as Jiri pointed out, that path is: printk vprintk_emit console_unlock up(&console_sem) __up wake_up_process try_to_wake_up ttwu_do_activate ttwu_activate activate_task enqueue_task enqueue_task_fair hrtick_update hrtick_start_fair hrtick_start_fair get_time ktime_get --> endless loop on read_seqcount_retry(&timekeeper_seq, ...) This patch tries to avoid this issue by using printk_deferred (previously named printk_sched) which should defer printing via a irq_work_queue. Signed-off-by: John Stultz <john.stultz@linaro.org> Reported-by: Jiri Bohac <jbohac@suse.cz> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Cc: Jan Kara <jack@suse.cz> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-05-12ntp: Make is_error_status() use its argumentGeorge Spelvin
is_error_status() is an inline function always called with the global time_status as an argument, so there's zero functional difference with this change, but the non-CONFIG_NTP_PPS version uses the passed-in argument, while the CONFIG_NTP_PPS one ignores its argument and uses the global. Looks like is_error_status was refactored out, but someone forgot to change the logic to check the local argument value. Thus this patch makes it use the argument always; shorter variable names are good. Signed-off-by: George Spelvin <linux@horizon.com> [jstultz: Tweaked commit message] Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-05-12ntp: Convert simple_strtol to kstrtolFabian Frederick
Replace obsolete function simple_strtol w/ kstrtol Inspired-By: Andrew Morton <akpm@linux-foundation.org> Cc: John Stultz <john.stultz@linaro.org> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Fabian Frederick <fabf@skynet.be> [jstultz: Tweak commit message] Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-02-07timekeeping: Move clock sync work to power efficient workqueueShaibal Dutta
For better use of CPU idle time, allow the scheduler to select the CPU on which the CMOS clock sync work would be scheduled. This improves idle residency time and conserver power. This functionality is enabled when CONFIG_WQ_POWER_EFFICIENT is selected. Signed-off-by: Shaibal Dutta <shaibal.dutta@broadcom.com> [zoran.markovic@linaro.org: Added commit message. Aligned code.] Signed-off-by: Zoran Markovic <zoran.markovic@linaro.org> Cc: John Stultz <john.stultz@linaro.org> Link: http://lkml.kernel.org/r/1391195904-12497-1-git-send-email-zoran.markovic@linaro.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2013-10-03Merge tag 'v3.12-rc3' into timers/coreIngo Molnar
Merge Linux 3.12-rc3 - refresh the tree with the latest fixes before merging new bits. Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-09-12timekeeping: Fix HRTICK related deadlock from ntp lock changesJohn Stultz
Gerlando Falauto reported that when HRTICK is enabled, it is possible to trigger system deadlocks. These were hard to reproduce, as HRTICK has been broken in the past, but seemed to be connected to the timekeeping_seq lock. Since seqlock/seqcount's aren't supported w/ lockdep, I added some extra spinlock based locking and triggered the following lockdep output: [ 15.849182] ntpd/4062 is trying to acquire lock: [ 15.849765] (&(&pool->lock)->rlock){..-...}, at: [<ffffffff810aa9b5>] __queue_work+0x145/0x480 [ 15.850051] [ 15.850051] but task is already holding lock: [ 15.850051] (timekeeper_lock){-.-.-.}, at: [<ffffffff810df6df>] do_adjtimex+0x7f/0x100 <snip> [ 15.850051] Chain exists of: &(&pool->lock)->rlock --> &p->pi_lock --> timekeeper_lock [ 15.850051] Possible unsafe locking scenario: [ 15.850051] [ 15.850051] CPU0 CPU1 [ 15.850051] ---- ---- [ 15.850051] lock(timekeeper_lock); [ 15.850051] lock(&p->pi_lock); [ 15.850051] lock(timekeeper_lock); [ 15.850051] lock(&(&pool->lock)->rlock); [ 15.850051] [ 15.850051] *** DEADLOCK *** The deadlock was introduced by 06c017fdd4dc48451a ("timekeeping: Hold timekeepering locks in do_adjtimex and hardpps") in 3.10 This patch avoids this deadlock, by moving the call to schedule_delayed_work() outside of the timekeeper lock critical section. Reported-by: Gerlando Falauto <gerlando.falauto@keymile.com> Tested-by: Lin Ming <minggr@gmail.com> Signed-off-by: John Stultz <john.stultz@linaro.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: stable <stable@vger.kernel.org> #3.11, 3.10 Link: http://lkml.kernel.org/r/1378943457-27314-1-git-send-email-john.stultz@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-08-22ntp: Make periodic RTC update more reliableMiroslav Lichvar
The current code requires that the scheduled update of the RTC happens in the closest tick to the half of the second. This seems to be difficult to achieve reliably. The scheduled work may be missing the target time by a tick or two and be constantly rescheduled every second. Relax the limit to 10 ticks. As a typical RTC drifts in the 11-minute update interval by several milliseconds, this shouldn't affect the overall accuracy of the RTC much. Signed-off-by: Miroslav Lichvar <mlichvar@redhat.com> Signed-off-by: John Stultz <john.stultz@linaro.org>
2013-05-28ntp: Remove unused variable flags in __hardppsGeert Uytterhoeven
kernel/time/ntp.c: In function ‘__hardpps’: kernel/time/ntp.c:877: warning: unused variable ‘flags’ commit a076b2146fabb0894cae5e0189a8ba3f1502d737 ("ntp: Remove ntp_lock, using the timekeeping locks to protect ntp state") removed its users, but not the actual variable. Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: John Stultz <john.stultz@linaro.org>
2013-04-04ntp: Remove ntp_lock, using the timekeeping locks to protect ntp stateJohn Stultz
In order to properly handle the NTP state in future changes to the timekeeping lock management, this patch moves the management of all of the ntp state under the timekeeping locks. This allows us to remove the ntp_lock. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Prarit Bhargava <prarit@redhat.com> Signed-off-by: John Stultz <john.stultz@linaro.org>
2013-04-04timekeeping: Move ADJ_SETOFFSET to top level do_adjtimex()John Stultz
Since ADJ_SETOFFSET adjusts the timekeeping state, process it as part of the top level do_adjtimex() function in timekeeping.c. This avoids deadlocks that could occur once we change the ntp locking rules. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Prarit Bhargava <prarit@redhat.com> Signed-off-by: John Stultz <john.stultz@linaro.org>
2013-04-04ntp: Rework do_adjtimex to take timespec and tai argumentsJohn Stultz
In order to change the locking rules, we need to provide the timespec and tai values rather then having the ntp logic acquire these values itself. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Prarit Bhargava <prarit@redhat.com> Signed-off-by: John Stultz <john.stultz@linaro.org>
2013-04-04ntp: Move timex validation to timekeeping do_adjtimex call.John Stultz
Move logic that does not need the ntp state to be done in the timekeeping do_adjtimex() call. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Prarit Bhargava <prarit@redhat.com> Signed-off-by: John Stultz <john.stultz@linaro.org>
2013-04-04ntp: Move do_adjtimex() and hardpps() functions to timekeeping.cJohn Stultz
In preparation for changing the ntp locking rules, move do_adjtimex and hardpps accessor functions to timekeeping.c, but keep the code logic in ntp.c. This patch also introduces a ntp_internal.h file so timekeeping specific interfaces of ntp.c can be more limitedly shared with timekeeping.c. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Prarit Bhargava <prarit@redhat.com> Signed-off-by: John Stultz <john.stultz@linaro.org>
2013-04-04ntp: Split out timex validation from do_adjtimexJohn Stultz
Split out the timex validation done in do_adjtimex into a separate function. This will help simplify logic in following patches. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Prarit Bhargava <prarit@redhat.com> Signed-off-by: John Stultz <john.stultz@linaro.org>
2013-03-22timekeeping: Move TAI managment into timekeeping core from ntpJohn Stultz
Currently NTP manages the TAI offset. Since there's plans for a CLOCK_TAI clockid, push the TAI management into the timekeeping core. CC: Thomas Gleixner <tglx@linutronix.de> CC: Eric Dumazet <eric.dumazet@gmail.com> CC: Richard Cochran <richardcochran@gmail.com> Signed-off-by: John Stultz <john.stultz@linaro.org>
2013-02-22Merge branch 'core-locking-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull core locking changes from Ingo Molnar: "The biggest change is the rwsem lock-steal improvements, both to the assembly optimized and the spinlock based variants. The other notable change is the clean up of the seqlock implementation to be based on the seqcount infrastructure. The rest is assorted smaller debuggability, cleanup and continued -rt locking changes." * 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: rwsem-spinlock: Implement writer lock-stealing for better scalability futex: Revert "futex: Mark get_robust_list as deprecated" generic: Use raw local irq variant for generic cmpxchg lockdep: Selftest: convert spinlock to raw spinlock seqlock: Use seqcount infrastructure seqlock: Remove unused functions ntp: Make ntp_lock raw intel_idle: Convert i7300_idle_lock to raw_spinlock locking: Various static lock initializer fixes lockdep: Print more info when MAX_LOCK_DEPTH is exceeded rwsem: Implement writer lock-stealing for better scalability lockdep: Silence warning if CONFIG_LOCKDEP isn't set watchdog: Use local_clock for get_timestamp() lockdep: Rename print_unlock_inbalance_bug() to print_unlock_imbalance_bug() locking/stat: Fix a typo
2013-02-19ntp: Make ntp_lock rawThomas Gleixner
seconds_overflow() is called from hard interrupt context even on Preempt-RT. This requires the lock to be a raw_spinlock. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: John Stultz <john.stultz@linaro.org> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-02-08time, Fix setting of hardware clock in NTP codePrarit Bhargava
At init time, if the system time is "warped" forward in warp_clock() it will differ from the hardware clock by sys_tz.tz_minuteswest. This time difference is not taken into account when ntp updates the hardware clock, and this causes the system time to jump forward by this offset every reboot. The kernel must take this offset into account when writing the system time to the hardware clock in the ntp code. This patch adds persistent_clock_is_local which indicates that an offset has been applied in warp_clock() and accounts for the "warp" before writing the hardware clock. x86 does not have this problem as rtc writes are software limited to a +/-15 minute window relative to the current rtc time. Other arches, such as powerpc, however do a full synchronization of the system time to the rtc and will see this problem. [v2]: generated against tip/timers/core Signed-off-by: Prarit Bhargava <prarit@redhat.com> Cc: John Stultz <john.stultz@linaro.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2013-01-15NTP: Add a CONFIG_RTC_SYSTOHC configurationJason Gunthorpe
The purpose of this option is to allow ARM/etc systems that rely on the class RTC subsystem to have the same kind of automatic NTP based synchronization that we have on PC platforms. Today ARM does not implement update_persistent_clock and makes extensive use of the class RTC system. When enabled CONFIG_RTC_SYSTOHC will provide a generic rtc_update_persistent_clock that stores the current time in the RTC and is intended complement the existing CONFIG_RTC_HCTOSYS option that loads the RTC at boot. Like with RTC_HCTOSYS the platform's update_persistent_clock is used first, if it works. Platforms with mixed class RTC and non-RTC drivers need to return ENODEV when class RTC should be used. Such an update for PPC is included in this patch. Long term, implementations of update_persistent_clock should migrate to proper class RTC drivers and use CONFIG_RTC_SYSTOHC instead. Tested on ARM kirkwood and PPC405 Signed-off-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com> Signed-off-by: John Stultz <john.stultz@linaro.org>
2012-07-31time/jiffies: Rename ACTHZ to SHIFTED_HZJohn Stultz
Ingo noted that ACTHZ is a confusing name, and requested it be renamed, so this patch renames ACTHZ to SHIFTED_HZ to better describe it. Signed-off-by: John Stultz <john.stultz@linaro.org> Cc: Prarit Bhargava <prarit@redhat.com> Link: http://lkml.kernel.org/r/1343414893-45779-3-git-send-email-john.stultz@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2012-07-15ntp: Fix STA_INS/DEL clearing bugJohn Stultz
In commit 6b43ae8a619d17c4935c3320d2ef9e92bdeed05d, I introduced a bug that kept the STA_INS or STA_DEL bit from being cleared from time_status via adjtimex() without forcing STA_PLL first. Usually once the STA_INS is set, it isn't cleared until the leap second is applied, so its unlikely this affected anyone. However during testing I noticed it took some effort to cancel a leap second once STA_INS was set. Signed-off-by: John Stultz <johnstul@us.ibm.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Prarit Bhargava <prarit@redhat.com> CC: stable@vger.kernel.org # 3.4 Link: http://lkml.kernel.org/r/1342156917-25092-2-git-send-email-john.stultz@linaro.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2012-05-21ntp: Fix a stale comment and a few stray newlines.Richard Cochran
Signed-off-by: Richard Cochran <richardcochran@gmail.com> Signed-off-by: John Stultz <john.stultz@linaro.org>
2012-05-21ntp: Correct TAI offset during leap secondRichard Cochran
When repeating a UTC time value during a leap second (when the UTC time should be 23:59:60), the TAI timescale should not stop. The kernel NTP code increments the TAI offset one second too late. This patch fixes the issue by incrementing the offset during the leap second itself. Signed-off-by: Richard Cochran <richardcochran@gmail.com> Signed-off-by: John Stultz <john.stultz@linaro.org>
2012-03-23time: remove no_sync_cmos_clockCesar Eduardo Barros
Commit 9863c90f682fba34cdc26c3437e8c00da6c83fa4 (x86, vmware: Remove deprecated VMI kernel support) removed the only place which set no_sync_cmos_clock. Since that commit, this variable is never set. Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net> Signed-off-by: John Stultz <john.stultz@linaro.org>
2012-03-22ntp: Fix leap-second hrtimer livelockJohn Stultz
Since commit 7dffa3c673fbcf835cd7be80bb4aec8ad3f51168 the ntp subsystem has used an hrtimer for triggering the leapsecond adjustment. However, this can cause a potential livelock. Thomas diagnosed this as the following pattern: CPU 0 CPU 1 do_adjtimex() spin_lock_irq(&ntp_lock); process_adjtimex_modes(); timer_interrupt() process_adj_status(); do_timer() ntp_start_leap_timer(); write_lock(&xtime_lock); hrtimer_start(); update_wall_time(); hrtimer_reprogram(); ntp_tick_length() tick_program_event() spin_lock(&ntp_lock); clockevents_program_event() ktime_get() seq = req_seqbegin(xtime_lock); This patch tries to avoid the problem by reverting back to not using an hrtimer to inject leapseconds, and instead we handle the leapsecond processing in the second_overflow() function. The downside to this change is that on systems that support highres timers, the leap second processing will occur on a HZ tick boundary, (ie: ~1-10ms, depending on HZ) after the leap second instead of possibly sooner (~34us in my tests w/ x86_64 lapic). This patch applies on top of tip/timers/core. CC: Sasha Levin <levinsasha928@gmail.com> CC: Thomas Gleixner <tglx@linutronix.de> Reported-by: Sasha Levin <levinsasha928@gmail.com> Diagnoised-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Sasha Levin <levinsasha928@gmail.com> Signed-off-by: John Stultz <john.stultz@linaro.org>
2012-03-15ntp: Fix integer overflow when setting timeSasha Levin
'long secs' is passed as divisor to div_s64, which accepts a 32bit divisor. On 64bit machines that value is trimmed back from 8 bytes back to 4, causing a divide by zero when the number is bigger than (1 << 32) - 1 and all 32 lower bits are 0. Use div64_long() instead. Signed-off-by: Sasha Levin <levinsasha928@gmail.com> Cc: johnstul@us.ibm.com Link: http://lkml.kernel.org/r/1331829374-31543-2-git-send-email-levinsasha928@gmail.com Cc: stable@vger.kernel.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2012-01-26ntp: Add ntp_lock to replace xtime_lockingJohn Stultz
Use a ntp_lock spin lock to replace xtime_lock locking in ntp.c CC: Thomas Gleixner <tglx@linutronix.de> CC: Eric Dumazet <eric.dumazet@gmail.com> CC: Richard Cochran <richardcochran@gmail.com> Signed-off-by: John Stultz <john.stultz@linaro.org>
2012-01-26ntp: Access tick_length variable via ntp_tick_length()John Stultz
Currently the NTP managed tick_length value is accessed globally, in preparations for locking cleanups, make sure it is accessed via a function and mark it as static. CC: Thomas Gleixner <tglx@linutronix.de> CC: Eric Dumazet <eric.dumazet@gmail.com> CC: Richard Cochran <richardcochran@gmail.com> Signed-off-by: John Stultz <john.stultz@linaro.org>
2012-01-26ntp: Cleanup timex.hJohn Stultz
Move ntp_sycned to ntp.c and mark time_status as static. Also yank function declaration for non-existant function. CC: Thomas Gleixner <tglx@linutronix.de> CC: Eric Dumazet <eric.dumazet@gmail.com> CC: Richard Cochran <richardcochran@gmail.com> Signed-off-by: John Stultz <john.stultz@linaro.org>
2011-04-04ntp: fix non privileged system time shiftingRichard Cochran
The ADJ_SETOFFSET bit added in commit 094aa188 ("ntp: Add ADJ_SETOFFSET mode bit") also introduced a way for any user to change the system time. Sneaky or buggy calls to adjtimex() could set ADJ_OFFSET_SS_READ | ADJ_SETOFFSET which would result in a successful call to timekeeping_inject_offset(). This patch fixes the issue by adding the capability check. Signed-off-by: Richard Cochran <richard.cochran@omicron.at> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-02-18ntp: Remove redundant and incorrect parameter checkRichard Cochran
The ADJ_SETOFFSET code redundantly checks the range of the nanoseconds field of the time value. This field is checked again in the subsequent call to timekeeping_inject_offset(). Also, as is, the check will not detect whether the number of microseconds is out of range. Let timekeeping_inject_offset() do the error checking. Signed-off-by: Richard Cochran <richard.cochran@omicron.at> Cc: johnstul@us.ibm.com LKML-Reference: <20110218090724.GA2924@riccoc20.at.omicron.at> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-02-02ntp: Add ADJ_SETOFFSET mode bitRichard Cochran
This patch adds a new mode bit into the timex structure. When set, the bit instructs the kernel to add the given time value to the current time. Signed-off-by: Richard Cochran <richard.cochran@omicron.at> Acked-by: John Stultz <johnstul@us.ibm.com> LKML-Reference: <20110201134320.688829863@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-01-31time: Make do_timer() and xtime_lock local to kernel/time/Torben Hohn
All callers of do_timer() are converted to xtime_update(). The only users of xtime_lock are in kernel/time/. Make both local to kernel/time/ and remove them from the global header files. [ tglx: Reuse tick-internal.h instead of creating another local header file. Massaged changelog ] Signed-off-by: Torben Hohn <torbenh@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: johnstul@us.ibm.com Cc: yong.zhang0@gmail.com Cc: hch@infradead.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-01-13ntp: add hardpps implementationAlexander Gordeev
This commit adds hardpps() implementation based upon the original one from the NTPv4 reference kernel code from David Mills. However, it is highly optimized towards very fast syncronization and maximum stickness to PPS signal. The typical error is less then a microsecond. To make it sync faster I had to throw away exponential phase filter so that the full phase offset is corrected immediately. Then I also had to throw away median phase filter because it gives a bigger error itself if used without exponential filter. Maybe we will find an appropriate filtering scheme in the future but it's not necessary if the signal quality is ok. Signed-off-by: Alexander Gordeev <lasaine@lvk.cs.msu.su> Acked-by: John Stultz <johnstul@us.ibm.com> Cc: Rodolfo Giometti <giometti@enneenne.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-09-09ntp: Clamp PLL update intervalMiroslav Lichvar
Clamp update interval to reduce PLL gain with low sampling rate (e.g. intermittent network connection) to avoid instability. The clamp roughly corresponds to the loop time constant, it's 8 * poll interval for SHIFT_PLL 2 and 32 * poll interval for SHIFT_PLL 4. This gives good results without affecting the gain in normal conditions where ntpd skips only up to seven consecutive samples. Signed-off-by: Miroslav Lichvar <mlichvar@redhat.com> Acked-by: john stultz <johnstul@us.ibm.com> LKML-Reference: <1283870626-9472-1-git-send-email-mlichvar@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2010-03-23ntp: Make time_adjust staticJohn Stultz
Now that no arches are accessing time_adjust directly, make it static. Signed-off-by: John Stultz <johnstul@us.ibm.com> LKML-Reference: <1268968769-19209-1-git-send-email-johnstul@us.ibm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2010-01-29ntp: Cleanup xtime references in ntp.cJohn Stultz
ntp.c doesn't need to access timekeeping internals directly, so change xtime references to use the get_seconds() timekeeping interface. Signed-off-by: John Stultz <johnstul@us.ibm.com> Cc: richard@rsk.demon.co.uk LKML-Reference: <1264738844-21935-1-git-send-email-johnstul@us.ibm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2010-01-29ntp: Make time_esterror and time_maxerror staticjohn stultz
Make time_esterror and time_maxerror static as no one uses them outside of ntp.c Signed-off-by: John Stultz <johnstul@us.ibm.com> Cc: richard@rsk.demon.co.uk LKML-Reference: <1264719761.3437.47.camel@localhost.localdomain> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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