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 389844E36EF for ; Mon, 19 Oct 2026 13:34:34 +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=1792416875; cv=none; b=WU3QV/zjNcRet2yIDtG63grGSu6HFVXAneSnS8SZx+YeA4mpriG7zSw1zwcNmOe0T6b27GY39gwloAqxLBw8YJenUBqPunH+5d7Gteg1QQk5Or6kiAd7nNC4e10hUhfynTt1emvb2Tz5rqNtVZZv+VlkZYwpJb/NMT3tYx1RABw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792416875; c=relaxed/simple; bh=MWxaae39WpacfBXQM6aGPKPsMovmW7LfVY3IunT46TQ=; h=Message-ID:From:Subject:To:Cc:In-Reply-To:References:Content-Type: Date; b=k70SEukWFpqO0fyqgLjdhi1PtKL5rs3HxPHeAFwZiJZZ+9lKQTpMC+H3Hl+iEzKis+QS6RTaBV/yPuvR1egwxo3BkKc/VlXracMBtn77AuOfskiQaYsHOT+9sHdWSpSzWcIwEPgxl2aXdmqeAyRcx5K4S6VrJuZjo3K6Par9lAA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=RSFQ2Ek1; 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="RSFQ2Ek1" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0A3641F000C4; Mon, 19 Oct 2026 13:34:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792416874; bh=AKvEnItM2m8WwTj/LT+h5DrQ5UB5SUsLoB6A1RqS/QY=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=RSFQ2Ek1UpZS4gQJoSkCFzi8PxD6XJSh/5jTyG6KCdIy+7YuOhWZM5f+lnzP8oHxM qMb675r30a+oFyrBjKHH7NHUBgCIQm37M96D5F3DaPHHP25N1obJ391q7a2N1YNf8u znhlpLH2vaY8SzGKY54I8cR4S95SmQs1CmdfIC7vL+ktItwnU8hjt/wHX52zc8cw+Q f/I9ZI9Ahi86mywDOkq12yn42EoGq2h8LlKpA0uoBJizVWq3gZtk4QOjM41U6ETdfd 8Xm9RKav3QAEa43rK1SrZL2zMKNMvYMVQV+ZEgtpdVsve02BoeZzi+xB8frm7yD8Jg BDE8fLHzjfZyw== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [RFC PATCH 14/49] perf/x86: Move CPUHP_AP_PERF_X86_STARTING post stop_machine() Reply-To: sashiko-reviews@lists.linux.dev To: "Frederic Weisbecker" Cc: linux-perf-users@vger.kernel.org In-Reply-To: <20261019130856.49711-15-frederic@kernel.org> References: <20261019130856.49711-1-frederic@kernel.org> <20261019130856.49711-15-frederic@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Mon, 19 Oct 2026 13:34:33 +0000 Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: > Between CPUHP_TEARDOWN_CPU and CPUHP_AP_OFFLINE, stop_machine executes > all the teardown callbacks while stopping all CPUs in the system. This > doesn't mix-up well with running RT or isolated tasks. >=20 > In order to transition smoothly from global stop_machine to finer > grained synchronization between teardown callbacks and the other CPUs, > a new stop machine post function has been introduced to be executed > after the main one with IRQs still disabled while other CPUs can exit > stop_machine(). >=20 > Here only intel has a dying callback (intel_pmu_cpu_dying()) which does: >=20 > * Deallocate the per CPU DS structure on the MSR_IA32_DS_AREA. This is > already racy against offlining CPUs because all possible CPUs's MSR > are written on a hardware event initialization, which still can happen > before the CPU actually goes off. >=20 > * Deallocate PEBS buffer. This is already well synchronized against > hotplug up callback. >=20 > Therefore the related teardwown callback can run concurrently with other > CPUs. >=20 > Move it to post stop_machine() accordingly. >=20 > Signed-off-by: Frederic Weisbecker Sashiko has reviewed this patch and found no issues. --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261019130856.4971= 1-1-frederic@kernel.org?part=3D14