From nobody Sun Dec 14 13:45:41 2025 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B60261D88AD; Wed, 15 Jan 2025 18:54:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736967266; cv=none; b=thWSERjwk0Ht3/owPd/p9D94yNgpy/VL5l6DV6JMsb59K38CDOJkQaEZk5gKP2/SU+Rlv0Mq+FRKoUAekwp7n//QIvNI0uAlJjpjHzuYJ3wTs0lzjuxT35XobXATGzruT4gzQju532AM4StbBAQLAgaMQ+hJRuaXi2cnEAeXqoo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736967266; c=relaxed/simple; bh=1+xPG6pmcuU5mUp3t9kRj0Efkdmo4oY7M+n79+qAZGQ=; h=Date:From:To:Subject:Cc:In-Reply-To:References:MIME-Version: Message-ID:Content-Type; b=aFq7sZi+I2SpRJMH3n99AEn31i2pftquDihMiau/wFY0xij1IYdAYgfXBMR0hEZ+Giw6xxImKTOKLIX+PGRErVBW7u0O53q3JQD6/0Ys92ipOFUmcSFhQvmCZ91Y48XzeYMmZDt2UwVGLDZHtkeK4lPK1VMyxoaR3gdNNSfpfCE= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=ST1SHREk; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=2O6pxK+U; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="ST1SHREk"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="2O6pxK+U" Date: Wed, 15 Jan 2025 18:54:20 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1736967262; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=UTXyWXZr96qpeq/kTIlIu9clYEXj9B08UOg47g/J6Zs=; b=ST1SHREkmMYJX4zvyvCjXbT4Gav/TF/ly5M1A74hci6zNNvVuvJcBQyZDqsGmXlW/igX+0 1fK3p94bUwvyaL23DfuG1z1hIjl74oYUFqU6V4eCp1Wo1+g2HG1Dm9oySNYJGZaZFHBaZK czJBrpi88SpSTJpNxMgicBHamRE/HNrFPvckfFB7eCxvHXjD1wD/dPZ17i7/CQAy3jNAlx N5bjEJGnPzv/IalO/UhGwrS3b9C3aAme0XmnBi0vAJp/M7ODtT0xMLkqTKwesEKFaw+80z QQVuCA9WBEXr02419wl4BNJ/eXA8dGaBQPWOqfn+1XZXvNDIm9qmUgrVkG3iGg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1736967262; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=UTXyWXZr96qpeq/kTIlIu9clYEXj9B08UOg47g/J6Zs=; b=2O6pxK+UQVdXKuXv/9ZVK6xPgkVFaYzAsw1Jl5nxdRTbRtT/fT4Q4ynNe5hNYH3iIjsyZx StUs6szNZchX56Bg== From: "tip-bot2 for Dr. David Alan Gilbert" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: timers/core] timekeeping: Remove unused ktime_get_fast_timestamps() Cc: "Dr. David Alan Gilbert" , Thomas Gleixner , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20250112160132.450209-1-linux@treblig.org> References: <20250112160132.450209-1-linux@treblig.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-ID: <173696726061.31546.10518774114228471040.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Precedence: bulk Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable The following commit has been merged into the timers/core branch of tip: Commit-ID: 2d2a46cf23788a19e5450c6f9c86ab17f596c708 Gitweb: https://git.kernel.org/tip/2d2a46cf23788a19e5450c6f9c86ab17f= 596c708 Author: Dr. David Alan Gilbert AuthorDate: Sun, 12 Jan 2025 16:01:32=20 Committer: Thomas Gleixner CommitterDate: Wed, 15 Jan 2025 19:49:14 +01:00 timekeeping: Remove unused ktime_get_fast_timestamps() ktime_get_fast_timestamps() was added in 2020 by commit e2d977c9f1ab ("timekeeping: Provide multi-timestamp accessor to NMI safe timekeeper") but has remained unused. Remove it. [ tglx: Fold the inline as David suggested in the submission ] Signed-off-by: Dr. David Alan Gilbert Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/all/20250112160132.450209-1-linux@treblig.org --- include/linux/timekeeping.h | 15 +------- kernel/time/timekeeping.c | 77 +++--------------------------------- 2 files changed, 8 insertions(+), 84 deletions(-) diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h index 0e035f6..5427736 100644 --- a/include/linux/timekeeping.h +++ b/include/linux/timekeeping.h @@ -264,18 +264,6 @@ extern bool timekeeping_rtc_skipresume(void); extern void timekeeping_inject_sleeptime64(const struct timespec64 *delta); =20 /** - * struct ktime_timestamps - Simultaneous mono/boot/real timestamps - * @mono: Monotonic timestamp - * @boot: Boottime timestamp - * @real: Realtime timestamp - */ -struct ktime_timestamps { - u64 mono; - u64 boot; - u64 real; -}; - -/** * struct system_time_snapshot - simultaneous raw/real time capture with * counter value * @cycles: Clocksource counter value to produce the system times @@ -345,9 +333,6 @@ extern int get_device_system_crosststamp( */ extern void ktime_get_snapshot(struct system_time_snapshot *systime_snapsh= ot); =20 -/* NMI safe mono/boot/realtime timestamps */ -extern void ktime_get_fast_timestamps(struct ktime_timestamps *snap); - /* * Persistent clock related interfaces */ diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 3d12882..1e67d07 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -485,91 +485,30 @@ u64 notrace ktime_get_tai_fast_ns(void) } EXPORT_SYMBOL_GPL(ktime_get_tai_fast_ns); =20 -static __always_inline u64 __ktime_get_real_fast(struct tk_fast *tkf, u64 = *mono) +/** + * ktime_get_real_fast_ns: - NMI safe and fast access to clock realtime. + * + * See ktime_get_mono_fast_ns() for documentation of the time stamp orderi= ng. + */ +u64 ktime_get_real_fast_ns(void) { + struct tk_fast *tkf =3D &tk_fast_mono; struct tk_read_base *tkr; - u64 basem, baser, delta; + u64 baser, delta; unsigned int seq; =20 do { seq =3D raw_read_seqcount_latch(&tkf->seq); tkr =3D tkf->base + (seq & 0x01); - basem =3D ktime_to_ns(tkr->base); baser =3D ktime_to_ns(tkr->base_real); delta =3D timekeeping_get_ns(tkr); } while (raw_read_seqcount_latch_retry(&tkf->seq, seq)); =20 - if (mono) - *mono =3D basem + delta; return baser + delta; } - -/** - * ktime_get_real_fast_ns: - NMI safe and fast access to clock realtime. - * - * See ktime_get_mono_fast_ns() for documentation of the time stamp orderi= ng. - */ -u64 ktime_get_real_fast_ns(void) -{ - return __ktime_get_real_fast(&tk_fast_mono, NULL); -} EXPORT_SYMBOL_GPL(ktime_get_real_fast_ns); =20 /** - * ktime_get_fast_timestamps: - NMI safe timestamps - * @snapshot: Pointer to timestamp storage - * - * Stores clock monotonic, boottime and realtime timestamps. - * - * Boot time is a racy access on 32bit systems if the sleep time injection - * happens late during resume and not in timekeeping_resume(). That could - * be avoided by expanding struct tk_read_base with boot offset for 32bit - * and adding more overhead to the update. As this is a hard to observe - * once per resume event which can be filtered with reasonable effort using - * the accurate mono/real timestamps, it's probably not worth the trouble. - * - * Aside of that it might be possible on 32 and 64 bit to observe the - * following when the sleep time injection happens late: - * - * CPU 0 CPU 1 - * timekeeping_resume() - * ktime_get_fast_timestamps() - * mono, real =3D __ktime_get_real_fast() - * inject_sleep_time() - * update boot offset - * boot =3D mono + bootoffset; - * - * That means that boot time already has the sleep time adjustment, but - * real time does not. On the next readout both are in sync again. - * - * Preventing this for 64bit is not really feasible without destroying the - * careful cache layout of the timekeeper because the sequence count and - * struct tk_read_base would then need two cache lines instead of one. - * - * Access to the time keeper clock source is disabled across the innermost - * steps of suspend/resume. The accessors still work, but the timestamps - * are frozen until time keeping is resumed which happens very early. - * - * For regular suspend/resume there is no observable difference vs. sched - * clock, but it might affect some of the nasty low level debug printks. - * - * OTOH, access to sched clock is not guaranteed across suspend/resume on - * all systems either so it depends on the hardware in use. - * - * If that turns out to be a real problem then this could be mitigated by - * using sched clock in a similar way as during early boot. But it's not as - * trivial as on early boot because it needs some careful protection - * against the clock monotonic timestamp jumping backwards on resume. - */ -void ktime_get_fast_timestamps(struct ktime_timestamps *snapshot) -{ - struct timekeeper *tk =3D &tk_core.timekeeper; - - snapshot->real =3D __ktime_get_real_fast(&tk_fast_mono, &snapshot->mono); - snapshot->boot =3D snapshot->mono + ktime_to_ns(data_race(tk->offs_boot)); -} - -/** * halt_fast_timekeeper - Prevent fast timekeeper from accessing clocksour= ce. * @tk: Timekeeper to snapshot. *