From mboxrd@z Thu Jan 1 00:00:00 1970 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 C233515E8B for ; Wed, 7 May 2025 00:42:28 +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=1746578548; cv=none; b=P9AacTfp2H6fu1rxeso2zP0KTNpfBU3PJHH/PWX0aaG3RDcGBQJlrDfg6jWNFbWIlHsZ8cRQr4ha23ZSTZCjJ+3E/nOTUr3Bdcm98wgxqCuuWpPABFFnRBr/wkyHrDXNwfiM13eqoiECkQDzsRBbqoXlnh+yIbYTxEBV2O8fY/8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746578548; c=relaxed/simple; bh=Rji2eeaP5Ev3tZhFRXgJ1dqG0yEWEdfxRUtVU++OOBo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=jklVwPt/N3MwpGGKFxE9LEcQsfiZmrV4StM6Iakq0DXsmay3PcnlPucF1nEGU22UKUm70/65CQTizy87OPSyPORpZSDJGiqPhwfL0XmrUxKhLvs9PY4/vfd98R8kKjGY8BKoqleNzVlS0Ve3pUjoWQrOKGzptYAi9SG1lKTykuQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fXU5YDUW; 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="fXU5YDUW" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 15B3FC4CEE4; Wed, 7 May 2025 00:42:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1746578548; bh=Rji2eeaP5Ev3tZhFRXgJ1dqG0yEWEdfxRUtVU++OOBo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=fXU5YDUWTN64fQMXIswVQUYm+mxjpE+TeCDtMAaJfVLUYkEOfAABNaOCse2f5F2zg 70C99BtzvTgbEgPljr+Z6CyGeSKXtl+H6Fm1ujBxyd3TU8/t2zLWhWfzO8IZKCaRgC kTndeo8NId4+xEc2O9s2BcLzwl9WFuzxeW9dIj9mRS+hiJdoWav7I64dbszAMLH/nf e79YBMK/oFLFHNwfCQ4faufy7xjsXeuGUQFvgXmCHiXVqJoHXR1chCw0jJwhHaKtfD lvdMWLrFSOac18/iP4NYLKUG6Hi2EYS+4AmKBJ1xFu+hJMJQp2H6CQcaDthD8VmpIS DFs9CxNBZmBeA== Date: Tue, 6 May 2025 14:42:26 -1000 From: Tejun Heo To: Frederic Weisbecker Cc: Marco Crivellari , linux-kernel@vger.kernel.org, Lai Jiangshan , Thomas Gleixner , Sebastian Andrzej Siewior Subject: Re: [PATCH 0/4] Workqueue: rename system workqueue and add WQ_PERCPU Message-ID: References: <20250503082834.49413-1-marco.crivellari@suse.com> 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=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Tue, May 06, 2025 at 02:55:14PM +0200, Frederic Weisbecker wrote: > Le Tue, May 06, 2025 at 12:10:18PM +0200, Marco Crivellari a écrit : > > Hi, > > > > > Can you please make a summary of the discussion here? Referring to old > > > thread is useful but it'd be nice to have the rationales laid out in the > > > patchset - why this is desirable, what is the transition plan and what are > > > the rationales for it? Also, please include a short summary in the patches. > > > > Sure, thanks for the advice. > > > > > Let's keep the old names for a release or two and trigger printk_once() > > > warnings about the renames. These are pretty widely used, so I think it > > > warrants a bit of extra effort. > > > > Good, sounds fine. > > But I don't understand where printk_once() should be placed. > > Can you give me some further guidance? > > So one possibility to achieve this is to not do a rename of system_wq > to system_percpu_wq but eventually keep system_wq around and create the > new system_percpu_wq. Convert all current users of system_wq to system_percpu_wq > and warn from queue_work() when system_wq is used. > > I would personally prefer that we use WARN_ON_ONCE() so that this really > gets noticed. Tejun what do you think? I'd stick with printk_once() at least for a while. There are systems set up to panic on warnings and there will be a bunch of out-of-tree usages too. Let's latch it up over multiple releases. Thanks. -- tejun