On Fri, Jun 26, 2026 at 05:17:52PM +0200, Thomas Gleixner wrote:
On Fri, Jun 26 2026 at 13:03, Thomas Weißschuh wrote:
quoted
On Fri, Jun 26, 2026 at 12:49:41PM +0200, Thomas Gleixner wrote:
quoted
On Fri, Jun 26 2026 at 10:48, Thomas Weißschuh wrote:
quoted
On Tue, May 26, 2026 at 07:14:13PM +0200, Thomas Gleixner wrote:
(...)
quoted
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'.
AUX clocks are independent in the first place and the MONORAW part is
the "MONORAW" related to the AUX clock itself.
quoted
Instead 'monoraw' should be computed based on 'tk_core'.
Which then also requires the sequence locking of 'tk_core'.
No. From a PTP and steering point of view you want the "raw" value which
is related to the AUX clock itself and not the global one.
Ack.
However the kdocs call it 'CLOCK_MONOTONIC_RAW'. Can we clean this up?
Yes. Something like the below?
Looks good, thanks.
The corresponding structure definitions are a also affected, though.
quoted hunk ↗ jump to hunk
Thanks,
tglx
------ a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -1202,10 +1202,21 @@ static inline u64 tk_clock_read_snapshot
/**
* ktime_get_snapshot_id - Simultaneously snapshot a given clock ID with
- * CLOCK_MONOTONIC_RAW and the underlying
+ * the corresponding monotonic raw the underlying
* clocksource counter value.
* @clock_id: The clock ID to snapshot
* @systime_snapshot: Pointer to struct receiving the system time snapshot
+ *
+ * For the system time keeping clocks (REALTIME, MONOTONIC and BOOTTIME) the
+ * monotonic raw clock is CLOCK_MONOTONIC_RAW. For AUX clocks this is the
+ * monotonic raw clock related to the AUX clock. These AUX clock related
+ * monotonic raw clocks have a strict linear offset to the system time
+ * CLOCK_MONOTONIC_RAW:
+ *
+ * MONOTONIC_RAW(AUX$N) = CLOCK_MONOTONIC_RAW(system) + offset(AUX$N)
+ *
+ * The offset is established when a AUX clock is initialized, but it is
+ * currently not accessible.
*/
void ktime_get_snapshot_id(clockid_t clock_id, struct system_time_snapshot *systime_snapshot)
{@@ -1512,6 +1523,9 @@ EXPORT_SYMBOL_GPL(ktime_real_to_base_clo
* @xtstamp: Receives simultaneously captured system and device time
*
* Reads a timestamp from a device and correlates it to system time
+ *
+ * See documentation for ktime_get_snapshot_id() for information about the raw
+ * monotonic time stamp which is used here.
*/
int get_device_system_crosststamp(int (*get_time_fn)
(ktime_t *device_time,