From nobody Wed Nov 27 18:47:56 2024 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 A4B6618FC83; Wed, 9 Oct 2024 08:29:23 +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=1728462565; cv=none; b=MJZFC0ynAz2uGzJbTLgZP5lV4yRPMjBjk4lL8Pt0nTms/VatmZjLEgj/Qxt7QYRl3w8ieEQhkz+bwXw6NGPpOxktqSLiggyJiKgHvoQhx6pGlZs0ILCdlHlAu5QMkqqwGK9uxq6vylc9OKW6Y5b9uE1M04ao0umQ2mLSG5low7o= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728462565; c=relaxed/simple; bh=JPb37VDuKMoRNJ9vp81Du4hr25S86cQJYo5RCttwRE0=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=mGmVACGNlZdqr2GAontVda/787G1/2QMTjDgPJHmE2hvxJhvFEUBW6zZ0lUzfs8jzDmyh7Ejz/iiuq8+3yPP6Fuc84lS4Lp1Tk5PDqWZabd4EU/c4rYMWTVM9vabUs7jwIfO0rYWsu+0GyOFSSTQ1ts2P2ffXlVNT0NNkrNysPw= 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=loBhx1E+; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=GoBj7OTt; 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="loBhx1E+"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="GoBj7OTt" From: Anna-Maria Behnsen DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1728462561; h=from:from: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=QXKFPtRu4Sx6Ya+F6FaITcYNeyub0Jgc6BL9e6PKQT8=; b=loBhx1E+vYnrxsr3U8V1ED4dJ0+WiD8wUa7ZlWp5tOHE7T7epQMBepx1ZqfpGodvrbE+MZ FTsmwawfoxtUt7bJhaLANkcT8pjyRBdaV7P7uq9yc30BraPuoBKeSnbOyM/E5RFIs2Darc 4fMHa8JFwMVz/OG9gELy5DGNdNvbZ4BiGtCnZwa95x30b7qA3JbdTTXKKnxarRPTrluRDI WUPd4y/GXXNv4KAtW3yOe2LwmQsxdj07L8RbcS5DC2oXBQJUnQuRTseeDBgaQnJSfLCQw4 CQ/7XvRifOQ+57EozhG6m9zP0JueJuRROyf7LIqMvLitf2HMW5C8Ku70fVG0Fg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1728462561; h=from:from: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=QXKFPtRu4Sx6Ya+F6FaITcYNeyub0Jgc6BL9e6PKQT8=; b=GoBj7OTtmqRlNlZCMMFa2AL8ftdeBqxfxnd/wtyir8pLMhX5AEJIqGQSAekXOyqiou14OB 4a6olzOLA2zxl5Cg== Date: Wed, 09 Oct 2024 10:29:15 +0200 Subject: [PATCH v2 22/25] timekeeping: Rework timekeeping_suspend() to use shadow_timekeeper Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20241009-devel-anna-maria-b4-timers-ptp-timekeeping-v2-22-554456a44a15@linutronix.de> References: <20241009-devel-anna-maria-b4-timers-ptp-timekeeping-v2-0-554456a44a15@linutronix.de> In-Reply-To: <20241009-devel-anna-maria-b4-timers-ptp-timekeeping-v2-0-554456a44a15@linutronix.de> To: John Stultz , Frederic Weisbecker , Thomas Gleixner Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org, Miroslav Lichvar , Richard Cochran , Christopher S Hall , Anna-Maria Behnsen From: Anna-Maria Behnsen Updates of the timekeeper can be done by operating on the shadow timekeeper and afterwards copying the result into the real timekeeper. This has the advantage, that the sequence count write protected region is kept as small as possible. While the sequence count held time is not relevant for the resume path as there is no concurrency, there is no reason to have this function different than all the other update sites. Convert timekeeping_inject_offset() to use this scheme and cleanup the variable declarations while at it. As halt_fast_timekeeper() does not need protection sequence counter, it is no problem to move it with this change outside of the sequence counter protected area. But it still needs to be executed while holding the lock. Signed-off-by: Anna-Maria Behnsen Acked-by: John Stultz --- kernel/time/timekeeping.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 63b7a1379ae8..e15e843ba2b8 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -1972,11 +1972,11 @@ void timekeeping_resume(void) =20 int timekeeping_suspend(void) { - struct timekeeper *tk =3D &tk_core.timekeeper; - unsigned long flags; - struct timespec64 delta, delta_delta; - static struct timespec64 old_delta; + struct timekeeper *tk =3D &tk_core.shadow_timekeeper; + struct timespec64 delta, delta_delta; + static struct timespec64 old_delta; struct clocksource *curr_clock; + unsigned long flags; u64 cycle_now; =20 read_persistent_clock64(&timekeeping_suspend_time); @@ -1992,7 +1992,6 @@ int timekeeping_suspend(void) suspend_timing_needed =3D true; =20 raw_spin_lock_irqsave(&tk_core.lock, flags); - write_seqcount_begin(&tk_core.seq); timekeeping_forward_now(tk); timekeeping_suspended =3D 1; =20 @@ -2027,9 +2026,8 @@ int timekeeping_suspend(void) } } =20 - timekeeping_update(&tk_core, tk, TK_MIRROR); + timekeeping_update_staged(&tk_core, 0); halt_fast_timekeeper(tk); - write_seqcount_end(&tk_core.seq); raw_spin_unlock_irqrestore(&tk_core.lock, flags); =20 tick_suspend(); --=20 2.39.5