From: "tip-bot2 for Peter Hilber" <tip-bot2@linutronix.de>
To: linux-tip-commits@vger.kernel.org
Cc: Peter Hilber <peter.hilber@opensynergy.com>,
Thomas Gleixner <tglx@linutronix.de>,
John Stultz <jstultz@google.com>,
x86@kernel.org, linux-kernel@vger.kernel.org
Subject: [tip: timers/core] timekeeping: Fix cross-timestamp interpolation for non-x86
Date: Mon, 19 Feb 2024 16:35:15 -0000 [thread overview]
Message-ID: <170836051538.398.6736189078796081366.tip-bot2@tip-bot2> (raw)
In-Reply-To: <20231218073849.35294-4-peter.hilber@opensynergy.com>
The following commit has been merged into the timers/core branch of tip:
Commit-ID: 14274d0bd31b4debf28284604589f596ad2e99f2
Gitweb: https://git.kernel.org/tip/14274d0bd31b4debf28284604589f596ad2e99f2
Author: Peter Hilber <peter.hilber@opensynergy.com>
AuthorDate: Mon, 18 Dec 2023 08:38:41 +01:00
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Mon, 19 Feb 2024 12:18:51 +01:00
timekeeping: Fix cross-timestamp interpolation for non-x86
So far, get_device_system_crosststamp() unconditionally passes
system_counterval.cycles to timekeeping_cycles_to_ns(). But when
interpolating system time (do_interp == true), system_counterval.cycles is
before tkr_mono.cycle_last, contrary to the timekeeping_cycles_to_ns()
expectations.
On x86, CONFIG_CLOCKSOURCE_VALIDATE_LAST_CYCLE will mitigate on
interpolating, setting delta to 0. With delta == 0, xtstamp->sys_monoraw
and xtstamp->sys_realtime are then set to the last update time, as
implicitly expected by adjust_historical_crosststamp(). On other
architectures, the resulting nonsense xtstamp->sys_monoraw and
xtstamp->sys_realtime corrupt the xtstamp (ts) adjustment in
adjust_historical_crosststamp().
Fix this by deriving xtstamp->sys_monoraw and xtstamp->sys_realtime from
the last update time when interpolating, by using the local variable
"cycles". The local variable already has the right value when
interpolating, unlike system_counterval.cycles.
Fixes: 2c756feb18d9 ("time: Add history to cross timestamp interface supporting slower devices")
Signed-off-by: Peter Hilber <peter.hilber@opensynergy.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <jstultz@google.com>
Link: https://lore.kernel.org/r/20231218073849.35294-4-peter.hilber@opensynergy.com
---
kernel/time/timekeeping.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 4e9f2f8..8aab7ed 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -1261,10 +1261,8 @@ int get_device_system_crosststamp(int (*get_time_fn)
tk_core.timekeeper.offs_real);
base_raw = tk->tkr_raw.base;
- nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono,
- system_counterval.cycles);
- nsec_raw = timekeeping_cycles_to_ns(&tk->tkr_raw,
- system_counterval.cycles);
+ nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono, cycles);
+ nsec_raw = timekeeping_cycles_to_ns(&tk->tkr_raw, cycles);
} while (read_seqcount_retry(&tk_core.seq, seq));
xtstamp->sys_realtime = ktime_add_ns(base_real, nsec_real);
next prev parent reply other threads:[~2024-02-19 16:35 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-18 7:38 [RFC PATCH v3 0/7] Add virtio_rtc module and related changes Peter Hilber
2023-12-18 7:38 ` [RFC PATCH v3 1/7] timekeeping: Fix cross-timestamp interpolation on counter wrap Peter Hilber
2024-02-19 16:35 ` [tip: timers/core] " tip-bot2 for Peter Hilber
2023-12-18 7:38 ` [RFC PATCH v3 2/7] timekeeping: Fix cross-timestamp interpolation corner case decision Peter Hilber
2024-02-19 16:35 ` [tip: timers/core] " tip-bot2 for Peter Hilber
2023-12-18 7:38 ` [RFC PATCH v3 3/7] timekeeping: Fix cross-timestamp interpolation for non-x86 Peter Hilber
2024-02-19 16:35 ` tip-bot2 for Peter Hilber [this message]
2023-12-18 7:38 ` [RFC PATCH v3 4/7] virtio_rtc: Add module and driver core Peter Hilber
2023-12-18 7:38 ` [RFC PATCH v3 5/7] virtio_rtc: Add PTP clocks Peter Hilber
2023-12-18 7:38 ` [RFC PATCH v3 6/7] virtio_rtc: Add Arm Generic Timer cross-timestamping Peter Hilber
2023-12-18 7:38 ` [RFC PATCH v3 7/7] virtio_rtc: Add RTC class driver Peter Hilber
2024-03-08 17:03 ` Alexandre Belloni
2024-03-11 18:28 ` Peter Hilber
2024-03-11 19:46 ` Alexandre Belloni
2024-03-13 9:13 ` Peter Hilber
2024-03-07 14:02 ` [RFC PATCH v3 0/7] Add virtio_rtc module and related changes David Woodhouse
2024-03-08 10:32 ` Peter Hilber
2024-03-08 12:33 ` David Woodhouse
2024-03-11 18:24 ` Peter Hilber
2024-03-12 17:15 ` David Woodhouse
2024-03-13 9:45 ` Peter Hilber
2024-03-13 11:18 ` Alexandre Belloni
2024-03-13 12:29 ` David Woodhouse
2024-03-13 12:58 ` Alexandre Belloni
2024-03-13 14:06 ` David Woodhouse
2024-03-13 14:50 ` Alexandre Belloni
2024-03-13 20:12 ` Andrew Lunn
2024-03-14 9:13 ` Peter Hilber
2024-03-13 17:50 ` Peter Hilber
2024-03-13 14:15 ` Peter Hilber
2024-03-13 12:45 ` David Woodhouse
2024-03-13 17:50 ` Peter Hilber
2024-03-13 18:18 ` David Woodhouse
2024-03-14 10:13 ` Peter Hilber
2024-03-14 14:19 ` David Woodhouse
2024-03-19 13:47 ` Peter Hilber
2024-03-20 17:22 ` David Woodhouse
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