Aksal/nuttx
3
1
Fork 1
mirror of https://github.com/apache/nuttx.git synced 2026-08-04 22:00:21 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 2
nuttx/sched/clock
History
dongjiuzhu1 3c486b98dd fs/timerfd: implement TFD_TIMER_CANCEL_ON_SET to detect clock changes 
Implement Linux-compatible TFD_TIMER_CANCEL_ON_SET flag for timerfd to
allow applications to detect discontinuous changes to CLOCK_REALTIME.

Background:
According to Linux timerfd_create(2) man page, when a timerfd is created
with CLOCK_REALTIME and TFD_TIMER_CANCEL_ON_SET flag is specified, the
read() operation should fail with ECANCELED if the real-time clock
undergoes a discontinuous change. This allows applications to detect
and respond to system time changes.

Implementation:
1. Add clock notifier infrastructure (clock_notifier.h/c) to notify
   interested parties when system time changes
2. Implement TFD_TIMER_CANCEL_ON_SET flag support in timerfd
3. Register timerfd with clock notifier when flag is set
4. Cancel timer and return ECANCELED when clock change is detected
5. Notify clock changes in:
   - clock_settime()
   - clock_initialize()
   - clock_timekeeping_set_wall_time()
   - rpmsg_rtc time synchronization

Changes include:
- New files: include/nuttx/clock_notifier.h, sched/clock/clock_notifier.c
- Modified: fs/vfs/fs_timerfd.c to handle TFD_TIMER_CANCEL_ON_SET
- Modified: clock subsystem to call notifier chain on time changes
- Modified: rpmsg_rtc to notify time changes during sync

Use case example:
Applications using timerfd with absolute time can now detect when
system time is adjusted (e.g., NTP sync, manual time change) and
take appropriate action such as recalculating timeouts or updating
scheduled events.

Reference: https://man7.org/linux/man-pages/man2/timerfd_create.2.html

Signed-off-by: dongjiuzhu1 <dongjiuzhu1@xiaomi.com>
2026-01-30 17:20:24 +08:00
..
clock.c sched: migrate to SPDX identifier 2024-09-12 01:10:14 +08:00
clock.h sched/clock: Remove perf_init to simplify the code 2026-01-26 21:14:38 +08:00
clock_adjtime.c sched/clock: support using CLOCKFD to call clock_adjtime 2025-12-30 10:22:09 -03:00
clock_getres.c sched/clock: support using CLOCKFD to call clock_getres 2025-12-30 10:22:09 -03:00
clock_gettime.c sched/clock: [bugfix] should return -EINVAL when clock_id is invalid 2025-12-30 10:22:09 -03:00
clock_initialize.c fs/timerfd: implement TFD_TIMER_CANCEL_ON_SET to detect clock changes 2026-01-30 17:20:24 +08:00
clock_notifier.c fs/timerfd: implement TFD_TIMER_CANCEL_ON_SET to detect clock changes 2026-01-30 17:20:24 +08:00
clock_perf.c libc/perf: userspace PMU access 2026-01-26 21:14:38 +08:00
clock_realtime2absticks.c clock: correct compile failed 2024-09-29 18:18:01 +08:00
clock_sched_ticks.c sched/clock: Make g_system_ticks a static variable 2025-11-13 18:40:16 -03:00
clock_settime.c fs/timerfd: implement TFD_TIMER_CANCEL_ON_SET to detect clock changes 2026-01-30 17:20:24 +08:00
clock_systime_ticks.c sched/clock: Remove unnecessary preprocessor definition 2025-12-12 12:31:16 +08:00
clock_systime_timespec.c sched/clock: Improve clock implementation with sched ticks functions 2025-10-18 20:07:59 +08:00
clock_timekeeping.c fs/timerfd: implement TFD_TIMER_CANCEL_ON_SET to detect clock changes 2026-01-30 17:20:24 +08:00
clock_timekeeping.h sched: migrate to SPDX identifier 2024-09-12 01:10:14 +08:00
CMakeLists.txt fs/timerfd: implement TFD_TIMER_CANCEL_ON_SET to detect clock changes 2026-01-30 17:20:24 +08:00
delay.c arch/udelay: Make common, weak definition of up_*delay functions 2025-09-29 09:22:56 +08:00
Make.defs fs/timerfd: implement TFD_TIMER_CANCEL_ON_SET to detect clock changes 2026-01-30 17:20:24 +08:00