From nobody Fri Dec 19 21:48:34 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 A51981DB125; Fri, 7 Nov 2025 19:07:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762542453; cv=none; b=pHLml3CALBirXZTsXQC/mNH3BvVByNK2m01QVkMIfwoycGLAr3qAhysLJ+zQGnwnKLTLPZR0YiTj5wxdgxdYZ1VkIXa6ur6nlbjlrfQNNblMYtScneyc63P78T0/pGpasWL6D1fGO9bvTNzRnm2coWQbkMmu/9HpxqPV/vvB63E= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762542453; c=relaxed/simple; bh=sryXcWbfbtKjRhof6o+o8YX3yFfe5opZuYDtIKsbm60=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version:Content-Type; b=m3ED+qEl0OGkOPNNhA3YOIC8HJet7f9aJI3zAM5aq6NB5A5/6+KX0ZpSbAQf+lcOTKTQYJ2AJ+1MK/oFAAGUJ1HvSrSUlkRc+7gokyM4/ptr9nUUi2XW2nj4MdHGhDpIgFgEjIqah9YyhPfnv1+i9TDYQXaJ/+bnJRpHRa+PruQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=vBhrDtkL; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="vBhrDtkL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8AD42C4CEF8; Fri, 7 Nov 2025 19:07:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1762542453; bh=sryXcWbfbtKjRhof6o+o8YX3yFfe5opZuYDtIKsbm60=; h=From:To:Cc:Subject:Date:From; b=vBhrDtkLzYRm/MJdhjPL6tLdpXslkDBcJKP5fty38Lu4v2z470PKURpRjuueEt2C4 Os6l8FPmzZmGVLVjxv0FXFOHMjifKxrFYYEHZO0YucLG52WFkZ38df/0/8WIrtX/1U nCx3ZDUCk3T9POoXZuNLwgxCgWZKuGK7/a+XD5sCUwXKXy2a0uByEMT0RX2cir7ZUF agMFrtbZ3cTiRp5JMhygrmjYTv9tu2O/G4VySOf+T+cdWhbk5ulRz9qPTmtmYIb5LR uYfO5+NPFsmFprcLL3AgZ2xhJh6dWW9NJRvIMqwIw3CLgv0jVhoB58jy299x6M6L70 hg2UyftlSczvQ== From: "Rafael J. Wysocki" To: Linux PM , Artem Bityutskiy Cc: LKML , Daniel Lezcano Subject: [PATCH v2] cpuidle: Add sanity check for exit latency and target residency Date: Fri, 07 Nov 2025 20:07:28 +0100 Message-ID: <12779486.O9o76ZdvQC@rafael.j.wysocki> Organization: Linux Kernel Development Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Rafael J. Wysocki Make __cpuidle_driver_init() fail if the exit latency of one of the driver's idle states is less than its exit latency which would break cpuidle assumptions. Signed-off-by: Rafael J. Wysocki Reviewed-by: Artem Bityutskiy Reviewed-by: Christian Loehle --- v1 -> v2: Make __cpuidle_driver_init() fail if the check is not passed (Art= em). --- drivers/cpuidle/driver.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) --- a/drivers/cpuidle/driver.c +++ b/drivers/cpuidle/driver.c @@ -152,7 +152,7 @@ static void cpuidle_setup_broadcast_time * __cpuidle_driver_init - initialize the driver's internal data * @drv: a valid pointer to a struct cpuidle_driver */ -static void __cpuidle_driver_init(struct cpuidle_driver *drv) +static int __cpuidle_driver_init(struct cpuidle_driver *drv) { int i; =20 @@ -193,7 +193,17 @@ static void __cpuidle_driver_init(struct s->exit_latency_ns =3D 0; else s->exit_latency =3D div_u64(s->exit_latency_ns, NSEC_PER_USEC); + + /* + * Ensure that the exit latency of a CPU idle state does not + * exceed its target residency which is assumed in cpuidle in + * multiple places. + */ + if (s->exit_latency_ns > s->target_residency_ns) + return -EINVAL; } + + return 0; } =20 /** @@ -223,7 +233,9 @@ static int __cpuidle_register_driver(str if (cpuidle_disabled()) return -ENODEV; =20 - __cpuidle_driver_init(drv); + ret =3D __cpuidle_driver_init(drv); + if (ret) + return ret; =20 ret =3D __cpuidle_set_driver(drv); if (ret)