From nobody Tue Apr 7 16:32:13 2026 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 AAB9E3BC691; Thu, 12 Mar 2026 11:25:28 +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=1773314729; cv=none; b=aFrxHQnmO5gZxdJzzgmYsMJ2pQ+TMXxnTpnzrNNjBAONNbvL6hYDdM1uCMlyW2v+RCjrLHRhC+zEeT8RqMutaRhS5+8itbO+L42rl1CxPjlyv6zud2nmXl2dbI5MBxSCyXBWFKVYiUFbznP2maexqKlNe2cebIZ8pzC0bolVsJ8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773314729; c=relaxed/simple; bh=A7ZDSpsv0EBRddny4U6jdrO5oKooCKUBUFw66FcQN64=; h=Date:From:To:Subject:Cc:In-Reply-To:References:MIME-Version: Message-ID:Content-Type; b=APjrri9NpPFU4J4dsf11S5vutv595679yVPJeHxF+Kv5eCIbe4cJ0vKj3TEH3ZyXCbCYP4kaqc6reAPKUGOfKzrdTIApvs8cJWHHhJ6K0kLSskFKhPJZQhDauTKvJUZ/Q1pRucB9gYvNC35NgC3gYBPJigiyUZ6oiffIykdKjLc= 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=N7DdxAUx; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=HXs3PhIT; 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="N7DdxAUx"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="HXs3PhIT" Date: Thu, 12 Mar 2026 11:25:24 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1773314726; 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=AH4Ew6+jbs2YIq74q4jxlcEY0S+oCN/tGAKLsKr372E=; b=N7DdxAUxtnsLckFUkQxBWvGe9BM5LIOw3OQVAGuviPjViq08Zw9ByKPxoI+ATdbXKFHK0V Rv4lT+nRhko8LW+BweccxZFP4/kq1o617WYGs4xw9i85NnTc924lcMOHUqgQAOG+zyMgkb jsu8G7OuX1iJA8VEbJLrG1ekr4dLOLUKP5mBwfmb5rJvSt25xl40lul5Hvgg3yl9ibO9S6 n2qCiOQifZZ9BwXkszC759uQQb7i5k5zKBFQJ8xJklh72IbzrC3350bJDWBJa+kLASOeh0 6D1mqTuH3NapCOC62tcyTsgsT1Qw5KDDKLF3efc/YbLRJaVvpZmEDq8tE2Mapg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1773314726; 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=AH4Ew6+jbs2YIq74q4jxlcEY0S+oCN/tGAKLsKr372E=; b=HXs3PhITYujRqVxTEtMCKjTa9EIvxBNOK2O4yPc6cWghzZpX8cAxDk0bOqibDrxNdqG9Y4 ypdkC8PNPIoTlNDg== From: "tip-bot2 for Thomas Gleixner" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: timers/core] clocksource: Don't use non-continuous clocksources as watchdog Cc: Thomas Gleixner , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20260123231521.858743259@kernel.org> References: <20260123231521.858743259@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-ID: <177331472458.1647592.8230030053274222586.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: 1432f9d4e8aa2d7585b678bdd0b740597af00d6e Gitweb: https://git.kernel.org/tip/1432f9d4e8aa2d7585b678bdd0b740597= af00d6e Author: Thomas Gleixner AuthorDate: Sat, 24 Jan 2026 00:17:57 +01:00 Committer: Thomas Gleixner CommitterDate: Thu, 12 Mar 2026 12:23:27 +01:00 clocksource: Don't use non-continuous clocksources as watchdog Using a non-continuous aka untrusted clocksource as a watchdog for another untrusted clocksource is equivalent to putting the fox in charge of the henhouse. That's especially true with the jiffies clocksource which depends on interrupt delivery based on a periodic timer. Neither the frequency of that timer is trustworthy nor the kernel's ability to react on it in a timely manner and rearm it if it is not self rearming. Just don't bother to deal with this. It's not worth the trouble and only relevant to museum piece hardware. Signed-off-by: Thomas Gleixner Link: https://patch.msgid.link/20260123231521.858743259@kernel.org --- kernel/time/clocksource.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c index 3c20544..e753a06 100644 --- a/kernel/time/clocksource.c +++ b/kernel/time/clocksource.c @@ -651,6 +651,13 @@ static void clocksource_select_watchdog(bool fallback) if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) continue; =20 + /* + * If it's not continuous, don't put the fox in charge of + * the henhouse. + */ + if (!(cs->flags & CLOCK_SOURCE_IS_CONTINUOUS)) + continue; + /* Skip current if we were requested for a fallback. */ if (fallback && cs =3D=3D old_wd) continue;