From f12b45862c4dcb9c2937b83ed730e473b9a76cbf Mon Sep 17 00:00:00 2001 From: Anna-Maria Behnsen Date: Mon, 19 May 2025 10:33:19 +0200 Subject: [PATCH] timekeeping: Introduce timekeeper ID As long as there is only a single timekeeper, there is no need to clarify which timekeeper is used. But with the upcoming reusage of the timekeeper infrastructure for auxiliary clock timekeepers, an ID is required to differentiate. Introduce an enum for timekeeper IDs, introduce a field in struct tk_data to store this timekeeper id and add also initialization. The id struct field is added at the end of the second cachline, as there is a 4 byte hole anyway. Signed-off-by: Anna-Maria Behnsen Signed-off-by: Thomas Gleixner Acked-by: John Stultz Link: https://lore.kernel.org/all/20250519083025.842476378@linutronix.de --- include/linux/timekeeper_internal.h | 14 +++++++++++++- kernel/time/timekeeping.c | 5 +++-- 2 files changed, 16 insertions(+), 3 deletions(-) diff --git a/include/linux/timekeeper_internal.h b/include/linux/timekeeper_internal.h index 785048a3b3e6..bfcecad0e279 100644 --- a/include/linux/timekeeper_internal.h +++ b/include/linux/timekeeper_internal.h @@ -11,6 +11,16 @@ #include #include +/** + * timekeeper_ids - IDs for various time keepers in the kernel + * @TIMEKEEPER_CORE: The central core timekeeper managing system time + * @TIMEKEEPERS_MAX: The maximum number of timekeepers managed + */ +enum timekeeper_ids { + TIMEKEEPER_CORE, + TIMEKEEPERS_MAX, +}; + /** * struct tk_read_base - base structure for timekeeping readout * @clock: Current clocksource used for timekeeping. @@ -52,6 +62,7 @@ struct tk_read_base { * @offs_boot: Offset clock monotonic -> clock boottime * @offs_tai: Offset clock monotonic -> clock tai * @coarse_nsec: The nanoseconds part for coarse time getters + * @id: The timekeeper ID * @tkr_raw: The readout base structure for CLOCK_MONOTONIC_RAW * @raw_sec: CLOCK_MONOTONIC_RAW time in seconds * @clock_was_set_seq: The sequence number of clock was set events @@ -101,7 +112,7 @@ struct tk_read_base { * which results in the following cacheline layout: * * 0: seqcount, tkr_mono - * 1: xtime_sec ... coarse_nsec + * 1: xtime_sec ... id * 2: tkr_raw, raw_sec * 3,4: Internal variables * @@ -123,6 +134,7 @@ struct timekeeper { ktime_t offs_boot; ktime_t offs_tai; u32 coarse_nsec; + enum timekeeper_ids id; /* Cacheline 2: */ struct tk_read_base tkr_raw; diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index fb1da87a92f1..f4692fc2ea6b 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -1663,10 +1663,11 @@ read_persistent_wall_and_boot_offset(struct timespec64 *wall_time, *boot_offset = ns_to_timespec64(local_clock()); } -static __init void tkd_basic_setup(struct tk_data *tkd) +static __init void tkd_basic_setup(struct tk_data *tkd, enum timekeeper_ids tk_id) { raw_spin_lock_init(&tkd->lock); seqcount_raw_spinlock_init(&tkd->seq, &tkd->lock); + tkd->timekeeper.id = tkd->shadow_timekeeper.id = tk_id; } /* @@ -1696,7 +1697,7 @@ void __init timekeeping_init(void) struct timekeeper *tks = &tk_core.shadow_timekeeper; struct clocksource *clock; - tkd_basic_setup(&tk_core); + tkd_basic_setup(&tk_core, TIMEKEEPER_CORE); read_persistent_wall_and_boot_offset(&wall_time, &boot_offset); if (timespec64_valid_settod(&wall_time) && -- 2.51.0