From mboxrd@z Thu Jan 1 00:00:00 1970 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 CFAEE36998E for ; Wed, 19 Nov 2025 18:15:49 +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=1763576155; cv=none; b=aBI1s90jPyLT8Oi3s58I+WIsnwEz+wIzgqhhME0RhO2CuHEHsOCU4Q2xJsb0jMqp1QvhqTKa2w0l+ooUVTWnrNaQFnfDC6bMRXFCEPWDNIVJimNtROjCBgQcCmAuV4ePy8fuK8LmudAPvmhMAinWvnTaFqPSvhcyG3jfTs3Flts= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763576155; c=relaxed/simple; bh=iKaXHWq5tiJQuNv099QS+Jyz9BUo8STx0MjMQsvtSEQ=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=GaSzdhP9dqJ6N0L6Dtp8MBbEyYpeK8ZsAXrnkJ/EA7QeplcpNPc73KFWhqn6DrMEnom866dvvFc51VbyaAb8V058MiBDz4hvzb55G1BsrNg/sj/ibBMUy4BtmIT32kCCcQArWqNBnRB7pu0OFDet2v2TPa3crtVIEnXeTpRlnSw= 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=SbVXqPZ3; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=eqSs3P1f; 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="SbVXqPZ3"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="eqSs3P1f" From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1763576142; 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=61Dhy+zq8BpzLNYHE3LA+36tCCDSkac/aRMWeIUtMxg=; b=SbVXqPZ3O4ZFVMewQusG0udkWf8Twr7nMMi9E2D2AYSY4zFsBX5GNxKXKjpw8JQnq/ZMAJ s4pI53Lpv3PYWTdMbCbo1we6hWxyxa96+y3GFMmZfg2gaLbToOA5z/CDk9z7yOnj5dTDtQ 8UZQKrOzIDWEGNP2thAkgIB0nnAfmnpXdOmFzRhQiddrRtKLHtPMyikdm2sh49ubkqW0Z6 LdE+AqRab/trOf9qrNoUaepPKozMdNbwfdoLY0LlPlthDMx0eutma0LZduHL+2r/f/Bkat llU2/nrI4e829sfT9jVGtpl4XlqQbgVLps3OvqwNpYRmkNNL8B1JvLcXCrjC+g== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1763576142; 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=61Dhy+zq8BpzLNYHE3LA+36tCCDSkac/aRMWeIUtMxg=; b=eqSs3P1fPZ7uXBhJTNBy4wIf8engekU2MAYy40QQ6XvtKIndODQ7IdXbYHIc66kl1APhK4 pxkXcRqg/gGERhDw== To: Frederic Weisbecker Cc: Gabriele Monaco , linux-kernel@vger.kernel.org, Anna-Maria Behnsen , Waiman Long , "John B. Wyatt IV" , "John B. Wyatt IV" Subject: Re: [PATCH v15 7/7] timers: Exclude isolated cpus from timer migration In-Reply-To: References: <20251113083324.33490-1-gmonaco@redhat.com> <20251113083324.33490-8-gmonaco@redhat.com> <87pl9eklvc.ffs@tglx> Date: Wed, 19 Nov 2025 19:15:42 +0100 Message-ID: <87jyzllwhd.ffs@tglx> 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 On Wed, Nov 19 2025 at 18:14, Frederic Weisbecker wrote: > Le Wed, Nov 19, 2025 at 05:50:15PM +0100, Thomas Gleixner a =C3=A9crit : >> But thinking more about it. What's the actual point of moving this 'clea= r' >> out instead of just moving it further down? >>=20 >> It does not matter at all whether the isol/unisol muck clears an already >> cleared bit or not. But it would keep the function name comprehensible >> and avoid all this online/offline wrapper nonsense. > > That was my suggestion. > > It's because tmigr_clear_cpu_available() and tmigr_set_cpu_available() > can now all be called concurrently through the workqueues and race and > mess up the cpumask if they all try to clear/set at the same time... Huch? cpumask_set_cpu() uses set_bit() and cpumask_clear_cpu() uses clear_bit(). Both are atomic and nothing gets messed up. The only undefined case would be if you end up setting/clearing the same bit, which would require that the unisol and isol maps overlap. But that would be a bug on it's own, no? Thanks, tglx