[tip: timers/ptp] timekeeping: Add CLOCK_AUX support for ktime_get_snapshot_id()

[tip-bot2 for Thomas Gleixner]

The following commit has been merged into the timers/ptp branch of tip:

Commit-ID:     a19658b83784d305ceed5bee3fdf5fdb955a5d1a
Gitweb:        https://git.kernel.org/tip/a19658b83784d305ceed5bee3fdf5fdb955a5d1a
Author:        Thomas Gleixner <tglx@xxxxxxxxxx>
AuthorDate:    Fri, 29 May 2026 22:00:24 +02:00
Committer:     Thomas Gleixner <tglx@xxxxxxxxxx>
CommitterDate: Tue, 02 Jun 2026 11:39:58 +02:00

timekeeping: Add CLOCK_AUX support for ktime_get_snapshot_id()

Now that all users are converted it's possible to enable snapshotting of
CLOCK_AUX time. The underlying clocksource is the same as for all other
CLOCK variants.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxx>
Tested-by: Arthur Kiyanovski <akiyano@xxxxxxxxxx>
Reviewed-by: David Woodhouse <dwmw@xxxxxxxxxxxx>
Reviewed-by: Thomas Weißschuh <thomas.weissschuh@xxxxxxxxxxxxx>
Reviewed-by: Jacob Keller <jacob.e.keller@xxxxxxxxx>
Link: https://patch.msgid.link/20260529195557.380601005@xxxxxxxxxx
---
 kernel/time/timekeeping.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index a134b1b..e43aa11 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -67,6 +67,7 @@ static inline bool tk_is_aux(const struct timekeeper *tk)
 {
 	return tk->id >= TIMEKEEPER_AUX_FIRST && tk->id <= TIMEKEEPER_AUX_LAST;
 }
+static inline struct tk_data *aux_get_tk_data(clockid_t id);
 #else
 static inline bool tk_get_aux_ts64(unsigned int tkid, struct timespec64 *ts)
 {
@@ -77,6 +78,10 @@ static inline bool tk_is_aux(const struct timekeeper *tk)
 {
 	return false;
 }
+static inline struct tk_data *aux_get_tk_data(clockid_t id)
+{
+	return NULL;
+}
 #endif
 
 static inline void tk_update_aux_offs(struct timekeeper *tk, ktime_t offs)
@@ -1218,6 +1223,12 @@ void ktime_get_snapshot_id(clockid_t clock_id, struct system_time_snapshot *syst
 		tkd = &tk_core;
 		offs = &tk_core.timekeeper.offs_boot;
 		break;
+	case CLOCK_AUX ... CLOCK_AUX_LAST:
+		tkd = aux_get_tk_data(clock_id);
+		if (!tkd)
+			return;
+		offs = &tkd->timekeeper.offs_aux;
+		break;
 	default:
 		WARN_ON_ONCE(1);
 		return;
@@ -1228,6 +1239,10 @@ void ktime_get_snapshot_id(clockid_t clock_id, struct system_time_snapshot *syst
 	do {
 		seq = read_seqcount_begin(&tkd->seq);
 
+		/* Aux clocks can be invalid */
+		if (!tk->clock_valid)
+			return;
+
 		now = tk_clock_read(&tk->tkr_mono);
 		systime_snapshot->cs_id = tk->tkr_mono.clock->id;
 		systime_snapshot->cs_was_changed_seq = tk->cs_was_changed_seq;