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35b603f8a7
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Benjamin ROBIN 35b603f8a7 ntp: Make sure RTC is synchronized when time goes backwards 
sync_hw_clock() is normally called every 11 minutes when time is
synchronized. This issue is that this periodic timer uses the REALTIME
clock, so when time moves backwards (the NTP server jumps into the past),
the timer expires late.

If the timer expires late, which can be days later, the RTC will no longer
be updated, which is an issue if the device is abruptly powered OFF during
this period. When the device will restart (when powered ON), it will have
the date prior to the ADJ_SETOFFSET call.

A normal NTP server should not jump in the past like that, but it is
possible... Another way of reproducing this issue is to use phc2sys to
synchronize the REALTIME clock with, for example, an IRIG timecode with
the source always starting at the same date (not synchronized).

Also, if the time jump in the future by less than 11 minutes, the RTC may
not be updated immediately (minor issue). Consider the following scenario:
 - Time is synchronized, and sync_hw_clock() was just called (the timer
   expires in 11 minutes).
 - A time jump is realized in the future by a couple of minutes.
 - The time is synchronized again.
 - Users may expect that RTC to be updated as soon as possible, and not
   after 11 minutes (for the same reason, if a power loss occurs in this
   period).

Cancel periodic timer on any time jump (ADJ_SETOFFSET) greater than or
equal to 1s. The timer will be relaunched at the end of do_adjtimex() if
NTP is still considered synced. Otherwise the timer will be relaunched
later when NTP is synced. This way, when the time is synchronized again,
the RTC is updated after less than 2 seconds.

Signed-off-by: Benjamin ROBIN <dev@benjarobin.fr>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20240908140836.203911-1-dev@benjarobin.fr
2024-09-10 13:50:40 +02:00
..
bpf bpf: add check for invalid name in btf_name_valid_section() 2024-09-04 11:56:34 -07:00
cgroup cgroup/cpuset: Eliminate unncessary sched domains rebuilds in hotplug 2024-08-05 10:54:25 -10:00
configs mm/slab: Plumb kmem_buckets into __do_kmalloc_node() 2024-07-03 12:24:19 +02:00
debug kdb: Get rid of redundant kdb_curr_task() 2024-06-21 15:49:29 +01:00
dma dma-debug: avoid deadlock between dma debug vs printk and netconsole 2024-08-06 10:29:32 -07:00
entry entry: Respect changes to system call number by trace_sys_enter() 2024-03-12 13:23:32 +01:00
events perf/aux: Fix AUX buffer serialization 2024-09-04 18:22:56 +02:00
futex printk: Change type of CONFIG_BASE_SMALL to bool 2024-05-06 17:39:09 +02:00
gcov gcov: add support for GCC 14 2024-06-15 10:43:06 -07:00
irq genirq/irqdesc: Honor caller provided affinity in alloc_desc() 2024-08-07 17:27:00 +02:00
kcsan kcsan: Add missing MODULE_DESCRIPTION() macro 2024-06-06 11:21:14 -07:00
livepatch livepatch: Replace snprintf() with sysfs_emit() 2024-07-02 16:56:18 +02:00
locking rtmutex: Drop rt_mutex::wait_lock before scheduling 2024-08-15 15:38:53 +02:00
module module: make waiting for a concurrent module loader interruptible 2024-08-09 08:33:28 -07:00
power mm: remove the implementation of swap_free() and always use swap_free_nr() 2024-07-03 19:30:01 -07:00
printk printk/panic: Allow cpu backtraces to be written into ringbuffer during panic 2024-08-13 14:16:22 +02:00
rcu Merge branches 'doc.2024.06.06a', 'fixes.2024.07.04a', 'mb.2024.06.28a', 'nocb.2024.06.03a', 'rcu-tasks.2024.06.06a', 'rcutorture.2024.06.06a' and 'srcu.2024.06.18a' into HEAD 2024-07-04 13:54:17 -07:00
sched Merge branch 'linus' into timers/core 2024-09-10 13:49:53 +02:00
time ntp: Make sure RTC is synchronized when time goes backwards 2024-09-10 13:50:40 +02:00
trace tracing/timerlat: Add interface_lock around clearing of kthread in stop_kthread() 2024-09-05 12:01:37 -04:00
.gitignore
acct.c kernel misc: Remove the now superfluous sentinel elements from ctl_table array 2024-04-24 09:43:53 +02:00
async.c async: Use a dedicated unbound workqueue with raised min_active 2024-02-09 11:13:59 -10:00
audit_fsnotify.c
audit_tree.c fsnotify: create a wrapper fsnotify_find_inode_mark() 2024-04-04 16:24:16 +02:00
audit_watch.c fsnotify: create a wrapper fsnotify_find_inode_mark() 2024-04-04 16:24:16 +02:00
audit.c audit: use KMEM_CACHE() instead of kmem_cache_create() 2024-01-25 10:12:22 -05:00
audit.h
auditfilter.c ima: Avoid blocking in RCU read-side critical section 2024-06-13 14:26:50 -04:00
auditsc.c audit,io_uring: io_uring openat triggers audit reference count underflow 2023-10-13 18:34:46 +02:00
backtracetest.c backtracetest: add MODULE_DESCRIPTION() 2024-06-24 22:24:55 -07:00
bounds.c bounds: Use the right number of bits for power-of-two CONFIG_NR_CPUS 2024-04-29 08:29:29 -07:00
capability.c lsm: constify the 'target' parameter in security_capget() 2023-08-08 16:48:47 -04:00
cfi.c
compat.c
configs.c
context_tracking.c context_tracking: Make context_tracking_key __ro_after_init 2024-03-22 11:18:18 +01:00
cpu_pm.c
cpu.c Merge branch 'linus' into timers/core 2024-09-10 13:49:53 +02:00
crash_core.c Mainly singleton patches, documented in their respective changelogs. 2024-05-19 14:02:03 -07:00
crash_reserve.c crash: fix riscv64 crash memory reserve dead loop 2024-08-15 22:16:16 -07:00
cred.c cred: Use KMEM_CACHE() instead of kmem_cache_create() 2024-02-23 17:33:31 -05:00
delayacct.c sysctl: treewide: constify the ctl_table argument of proc_handlers 2024-07-24 20:59:29 +02:00
dma.c
elfcorehdr.c crash: remove dependency of FA_DUMP on CRASH_DUMP 2024-02-23 17:48:22 -08:00
exec_domain.c
exit.c - 875fa64577 ("mm/hugetlb_vmemmap: fix race with speculative PFN 2024-07-21 17:15:46 -07:00
exit.h exit: add internal include file with helpers 2023-09-21 12:03:50 -06:00
extable.c
fail_function.c
fork.c Revert "pidfd: prevent creation of pidfds for kthreads" 2024-08-21 22:32:58 +02:00
freezer.c Linux 6.7-rc6 2023-12-23 15:52:13 +01:00
gen_kheaders.sh kheaders: use command -v to test for existence of cpio 2024-05-30 01:13:20 +09:00
groups.c groups: Convert group_info.usage to refcount_t 2023-09-29 11:28:39 -07:00
hung_task.c sysctl: treewide: constify the ctl_table argument of proc_handlers 2024-07-24 20:59:29 +02:00
iomem.c kernel/iomem.c: remove __weak ioremap_cache helper 2023-08-21 13:37:28 -07:00
irq_work.c
jump_label.c jump_label: Fix the fix, brown paper bags galore 2024-07-31 12:57:39 +02:00
kallsyms_internal.h kallsyms: get rid of code for absolute kallsyms 2024-07-20 16:33:21 +09:00
kallsyms_selftest.c kallsyms: Match symbols exactly with CONFIG_LTO_CLANG 2024-08-15 09:33:35 -07:00
kallsyms_selftest.h
kallsyms.c kallsyms: Match symbols exactly with CONFIG_LTO_CLANG 2024-08-15 09:33:35 -07:00
kcmp.c file: convert to SLAB_TYPESAFE_BY_RCU 2023-10-19 11:02:48 +02:00
Kconfig.freezer
Kconfig.hz
Kconfig.kexec crash: clean up kdump related config items 2024-02-23 17:48:22 -08:00
Kconfig.locks
Kconfig.preempt
kcov.c kcov: properly check for softirq context 2024-08-07 18:33:56 -07:00
kexec_core.c sysctl: treewide: constify the ctl_table argument of proc_handlers 2024-07-24 20:59:29 +02:00
kexec_elf.c
kexec_file.c kexec_file: fix elfcorehdr digest exclusion when CONFIG_CRASH_HOTPLUG=y 2024-09-01 17:59:01 -07:00
kexec_internal.h crash: remove dependency of FA_DUMP on CRASH_DUMP 2024-02-23 17:48:22 -08:00
kexec.c crash: add a new kexec flag for hotplug support 2024-04-23 14:59:01 +10:00
kheaders.c
kprobes.c kprobes: Fix to check symbol prefixes correctly 2024-08-05 14:04:03 +09:00
ksyms_common.c
ksysfs.c profiling: remove prof_cpu_mask 2024-07-29 10:45:54 -07:00
kthread.c kunit: Handle test faults 2024-05-06 14:22:02 -06:00
latencytop.c sysctl: treewide: constify the ctl_table argument of proc_handlers 2024-07-24 20:59:29 +02:00
Makefile crash: split crash dumping code out from kexec_core.c 2024-02-23 17:48:22 -08:00
module_signature.c
notifier.c
nsproxy.c pidfd: add pidfs 2024-03-01 12:23:37 +01:00
numa.c kernel/numa.c: Move logging out of numa.h 2023-12-20 19:26:30 -05:00
padata.c padata: Fix possible divide-by-0 panic in padata_mt_helper() 2024-08-07 18:33:56 -07:00
panic.c printk/panic: Allow cpu backtraces to be written into ringbuffer during panic 2024-08-13 14:16:22 +02:00
params.c params: Fix multi-line comment style 2023-12-01 09:51:44 -08:00
pid_namespace.c sysctl: treewide: constify the ctl_table argument of proc_handlers 2024-07-24 20:59:29 +02:00
pid_sysctl.h sysctl: treewide: constify the ctl_table argument of proc_handlers 2024-07-24 20:59:29 +02:00
pid.c pidfs: remove config option 2024-03-13 12:53:53 -07:00
profile.c profiling: remove profile=sleep support 2024-08-04 13:36:28 -07:00
ptrace.c ptrace_attach: shift send(SIGSTOP) into ptrace_set_stopped() 2024-02-22 15:38:52 -08:00
range.c
reboot.c kernel misc: Remove the now superfluous sentinel elements from ctl_table array 2024-04-24 09:43:53 +02:00
regset.c regset: use kvzalloc() for regset_get_alloc() 2024-04-25 21:07:03 -07:00
relay.c kernel: relay: remove relay_file_splice_read dead code, doesn't work 2023-12-29 12:22:27 -08:00
resource_kunit.c resource: add missing MODULE_DESCRIPTION() 2024-06-28 19:36:30 -07:00
resource.c x86/kaslr: Expose and use the end of the physical memory address space 2024-08-20 13:44:57 +02:00
rseq.c
scftorture.c scftorture: Make torture_type static 2024-05-30 15:31:51 -07:00
scs.c
seccomp.c sysctl: treewide: constify the ctl_table argument of proc_handlers 2024-07-24 20:59:29 +02:00
signal.c signal: Replace BUG_ON()s 2024-07-29 21:57:35 +02:00
smp.c smp: Add missing destroy_work_on_stack() call in smp_call_on_cpu() 2024-07-10 22:40:39 +02:00
smpboot.c kthread: add kthread_stop_put 2023-10-04 10:41:57 -07:00
smpboot.h
softirq.c softirq: Fix suspicious RCU usage in __do_softirq() 2024-04-29 05:03:51 +02:00
stackleak.c sysctl: treewide: constify the ctl_table argument of proc_handlers 2024-07-24 20:59:29 +02:00
stacktrace.c stacktrace: fix kernel-doc typo 2023-12-29 12:22:29 -08:00
static_call_inline.c
static_call.c
stop_machine.c
sys_ni.c Probes updates for v6.11: 2024-07-18 12:19:20 -07:00
sys.c hrtimer: Use and report correct timerslack values for realtime tasks 2024-08-23 20:13:02 +02:00
sysctl-test.c sysctl: Add module description to sysctl-testing 2024-06-03 15:20:37 +02:00
sysctl.c sysctl: treewide: constify the ctl_table argument of proc_handlers 2024-07-24 20:59:29 +02:00
task_work.c task_work: make TWA_NMI_CURRENT handling conditional on IRQ_WORK 2024-07-29 12:05:06 -07:00
taskstats.c taskstats: fill_stats_for_tgid: use for_each_thread() 2023-10-04 10:41:57 -07:00
torture.c torture: Add MODULE_DESCRIPTION() 2024-05-30 15:31:38 -07:00
tracepoint.c
tsacct.c tsacct: replace strncpy() with strscpy() 2024-07-12 16:39:53 -07:00
ucount.c sysctl changes for v6.10-rc1 2024-05-17 17:31:24 -07:00
uid16.c
uid16.h
umh.c sysctl: treewide: constify the ctl_table argument of proc_handlers 2024-07-24 20:59:29 +02:00
up.c smp: Change function signatures to use call_single_data_t 2023-09-13 14:59:24 +02:00
user_namespace.c user_namespace: remove unnecessary NULL values from kbuf 2024-02-22 15:38:52 -08:00
user-return-notifier.c
user.c printk: Change type of CONFIG_BASE_SMALL to bool 2024-05-06 17:39:09 +02:00
usermode_driver.c
utsname_sysctl.c sysctl: treewide: constify the ctl_table argument of proc_handlers 2024-07-24 20:59:29 +02:00
utsname.c
vhost_task.c vhost_task: Handle SIGKILL by flushing work and exiting 2024-05-22 08:31:15 -04:00
vmcore_info.c kallsyms: get rid of code for absolute kallsyms 2024-07-20 16:33:21 +09:00
watch_queue.c watch_queue: fix kcalloc() arguments order 2023-12-21 13:17:54 +01:00
watchdog_buddy.c
watchdog_perf.c watchdog/perf: properly initialize the turbo mode timestamp and rearm counter 2024-07-17 21:11:34 -07:00
watchdog.c sysctl: treewide: constify the ctl_table argument of proc_handlers 2024-07-24 20:59:29 +02:00
workqueue_internal.h workqueue: Drop the special locking rule for worker->flags and worker_pool->flags 2023-08-07 15:57:22 -10:00
workqueue.c workqueue: Correct declaration of cpu_pwq in struct workqueue_struct 2024-08-05 18:34:02 -10:00