From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 8918A5187DD for ; Tue, 29 Sep 2026 11:53:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790682827; cv=none; b=auGR5dlBha3HS/oiLqEq4/wth3YxcSs9P1QIXiRKwj/FcCMm79YdZUF7vH3jOoDOVZ/32pvwYaCy6r/bveJkAVJGG8Ct6zDFVdARI4eW8ZCGEBkZsUwsLU22cPTdhu5vQN7fOXjXOUQC6VQT9lj3aC8YL9W1OhiiPhGLc87edPQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790682827; c=relaxed/simple; bh=7j742CzvHo7Rqq5Ojk4XIcl/5a83GNl55B36u0QiQ5Y=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=C+H0niBDFk50EHG/bDMuOqcdcpKwop0BeWXBK0Gg8pWXyrxlCuWNK2G7JQ2zScyTKvE3qmF2NIVNeW+oZ+N3ue4K6huTbmo7yOlSF2jOJ5HsgzNcSnm0pHAVTq3NmSzC+0pybhROd/j6PVl7lUD6XL6i423ISvchTkPu7mtPXPM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=opqSDRsY; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="opqSDRsY" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B1BA91F00893; Tue, 29 Sep 2026 11:53:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790682826; bh=/xMuLzEzFMdx1SNrUMigxPA+Ybp9ReIE/88H0iZ1VL8=; h=From:To:Cc:Subject:In-Reply-To:References:Date; b=opqSDRsYwk0i+dnRZOCt045nv9doTYcluV/jVuLoYVLrsMC09p6z+AcZyfpEUwcJ8 0jQ0Zt2fmJCC7kbhoe1WdmfGKl3T8MzkrD57va4FEisoWuq/PNXUFRLEAk42yYjcoI qXb7AW5SN1oxj6XVVhd2podNg4wDHqcoPtjrIz3qa0tAZagRPCeA19cTu791A02PYJ y8jzI2VEOUPyHsZ1mgHWfmb09dX3QHlA/AWgifuEuL8bIcp6r/wp2u08hdIqyv3dTS nAT5dsYuvQbW3xcSO96/XihEMpBUIHSX1gTJGcpqMod2B32cat6AkIDCvM++vXeGKv vZVO235x2fdyw== From: Thomas Gleixner To: Jaidev Shastri via B4 Relay , John Stultz , Stephen Boyd , Miroslav Lichvar Cc: linux-kernel@vger.kernel.org, Jaidev Shastri Subject: Re: [PATCH] clocksource: publish finished_booting with release semantics In-Reply-To: <20260921-mb-clocksource-v1-1-3e1d1b43e90d@vt.edu> References: <20260921-mb-clocksource-v1-1-3e1d1b43e90d@vt.edu> Date: Tue, 29 Sep 2026 13:53:40 +0200 Message-ID: <87wls4i88r.ffs@fw13> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On Mon, Sep 21 2026 at 21:22, Jaidev Shastri via wrote: > From: Jaidev Shastri > > clocksource_done_booting() sets curr_clocksource and then > finished_booting, both with plain stores under clocksource_mutex. > clocksource_find_best() tests finished_booting with a plain load before > it walks clocksource_list. > > Set the flag with smp_store_release() and read it with > smp_load_acquire(). > > Found with MBCheck, a static herd7-based memory consistency checker. Unfortunately your tool is missing the point. All callchains which end up in clocksource_find_best() hold clocksource_mutex. So this acquire/release is pointless. Thanks, tglx