Re: [patch 09/24] timekeeping: Add CLOCK_AUX support for ktime_get_snapshot_id()

From
Thomas Weißschuh <hidden>
Date
2026-06-26 08:48:12
Also in
kvmarm, linux-sound, linux-wireless, lkml, virtualization
Reply to
Thomas Gleixner, 2026-05-26
On Tue, May 26, 2026 at 07:14:13PM +0200, Thomas Gleixner wrote:
(...)
quoted hunk ↗ jump to hunk
 static inline void tk_update_aux_offs(struct timekeeper *tk, ktime_t offs)
@@ -1218,6 +1223,12 @@ bool ktime_get_snapshot_id(struct system
 		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 false;
+		offs = &tkd->timekeeper.offs_aux;
+		break;
'tkd' is also used to compute 'monoraw'. However 'tkr_raw' and 'tkr_mono'
are the same for auxilary clocks, so this will compute a wrong 'monoraw'.
Instead 'monoraw' should be computed based on 'tk_core'.
Which then also requires the sequence locking of 'tk_core'.

As you know I have a series which unifies the locking between the
different timekeepers. Maybe we revert this patch for 7.2 and I send
a fixed variant including the prerequisites for 7.3.

(The same goes for get_device_system_crosststamp())
quoted hunk ↗ jump to hunk
 	default:
 		WARN_ON_ONCE(1);
 		return false;
@@ -1228,6 +1239,10 @@ bool ktime_get_snapshot_id(struct system
 	do {
 		seq = read_seqcount_begin(&tkd->seq);
 
+		/* Aux clocks can be invalid */
+		if (!tk->clock_valid)
+			return false;
+
 		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;
Thread (86 messages) 86 messages, 9 authors, last reply 2026-07-06
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