From nobody Sat Nov 30 07:37:11 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 785CB1AB50B; Wed, 11 Sep 2024 13:30:09 +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=1726061411; cv=none; b=frHEn2nLs333FWHyNiGO8N6OEFjD1n36p0lF9Auby4EiH7NBC1MTqJa6KR20feTEFHA8tgXj94BdkkQ07oi9wrI5suNuozMyLaVVfGS3dmaujXGigkFHeHf2DSXmb2q5MfeompzTxL51gloYoKZo3x3Jm6OHHoN0Uz5oFH4nkp4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726061411; c=relaxed/simple; bh=Zap0Yi50WGWo/Qq3DJFBEab4/jczvRrU1rzrv+RNAB0=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=MFmuvSu4m0xofWYHm885FVkA/01bhIjzhHH7UGJ/AQIcwxYtbiQNwahT8/b/5YYsn7Q54WWvTU7UL1va27wsaRl2DPO8gP1T7WxlHUAkka+TYy9WP9l2HY0vuMRXb3il5OGmF1g7oiTfn9Jlq7/ad7JsVtxsS8QdWmMI25qXb3I= 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=J7bQGwF/; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=cj9j3dOf; 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="J7bQGwF/"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="cj9j3dOf" From: Anna-Maria Behnsen DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1726061407; 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=iEUQhs/7XdMxctBGjdLZslFFIm8tsdgWFqBbte1umNA=; b=J7bQGwF/Ykf28YVcZIS/+8zktL8XcNHsqMvkuTWiP6VJKqspZ9unfDb7s0kNm5Bam8IhJF y8jYkGXtHMTz5rYbdC8ChX0323fNdXVQqD1+JqYYVOQYeX9lrzsWK2xv+cW6sJI32vUC7v AZR/TPbCmiZIn40wxG0ilGpYN4Y88hIZle5SGWa9BrFL3xj2CZ5rMpf65sEO9XRZSZ6ETa aGctmm2UYSaqCkKnssz9xiypkzC/sqPeSSMRi8UpMAZ3X1Ln2KzxqYV87YSUpgNFTvs2Dl oU4sXqkuYwl6j+Gdm+ctz71+T+WdwczuvZpk91TCtwx/3kpl29+EZzmHVfLlEA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1726061407; 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=iEUQhs/7XdMxctBGjdLZslFFIm8tsdgWFqBbte1umNA=; b=cj9j3dOfp6KG27Eo/id/h5JmNkTq8HL3W1p+pOwGAPymc1qaUwzP4DkH7waM1N0Bg4n16R Svk0BycF9KuRhYAQ== Date: Wed, 11 Sep 2024 15:29:59 +0200 Subject: [PATCH 15/24] timekeeping: Rework do_settimeofday64() 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: <20240911-devel-anna-maria-b4-timers-ptp-timekeeping-v1-15-f7cae09e25d6@linutronix.de> References: <20240911-devel-anna-maria-b4-timers-ptp-timekeeping-v1-0-f7cae09e25d6@linutronix.de> In-Reply-To: <20240911-devel-anna-maria-b4-timers-ptp-timekeeping-v1-0-f7cae09e25d6@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 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. Convert do_settimeofday64() to use this scheme. That allows to use a scoped_guard() for locking the timekeeper lock as the usage of the shadow timekeeper allows a rollback in the error case instead of the full timekeeper update of the original code. Signed-off-by: Anna-Maria Behnsen --- kernel/time/timekeeping.c | 42 ++++++++++++++++-------------------------- 1 file changed, 16 insertions(+), 26 deletions(-) diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 345117ff665d..efcfb0da351e 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -1479,45 +1479,35 @@ EXPORT_SYMBOL_GPL(timekeeping_clocksource_has_base); */ int do_settimeofday64(const struct timespec64 *ts) { - struct timekeeper *tk =3D &tk_core.timekeeper; struct timespec64 ts_delta, xt; - unsigned long flags; - int ret =3D 0; =20 if (!timespec64_valid_settod(ts)) return -EINVAL; =20 - raw_spin_lock_irqsave(&tk_core.lock, flags); - write_seqcount_begin(&tk_core.seq); - - timekeeping_forward_now(tk); - - xt =3D tk_xtime(tk); - ts_delta =3D timespec64_sub(*ts, xt); + scoped_guard (raw_spinlock_irqsave, &tk_core.lock) { + struct timekeeper *tk =3D &tk_core.shadow_timekeeper; =20 - if (timespec64_compare(&tk->wall_to_monotonic, &ts_delta) > 0) { - ret =3D -EINVAL; - goto out; - } + timekeeping_forward_now(tk); =20 - tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, ts_delta)); + xt =3D tk_xtime(tk); + ts_delta =3D timespec64_sub(*ts, xt); =20 - tk_set_xtime(tk, ts); -out: - timekeeping_update(&tk_core, tk, TK_UPDATE_ALL | TK_MIRROR); + if (timespec64_compare(&tk->wall_to_monotonic, &ts_delta) > 0) { + timekeeping_restore_shadow(&tk_core); + return -EINVAL; + } =20 - write_seqcount_end(&tk_core.seq); - raw_spin_unlock_irqrestore(&tk_core.lock, flags); + tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, ts_delta)); + tk_set_xtime(tk, ts); + timekeeping_update_staged(&tk_core, TK_UPDATE_ALL); + } =20 /* Signal hrtimers about time change */ clock_was_set(CLOCK_SET_WALL); =20 - if (!ret) { - audit_tk_injoffset(ts_delta); - add_device_randomness(ts, sizeof(*ts)); - } - - return ret; + audit_tk_injoffset(ts_delta); + add_device_randomness(ts, sizeof(*ts)); + return 0; } EXPORT_SYMBOL(do_settimeofday64); =20 --=20 2.39.2