From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1754830AbaJGReP (ORCPT <rfc822;w@1wt.eu>);
	Tue, 7 Oct 2014 13:34:15 -0400
Received: from mail-vc0-f172.google.com ([209.85.220.172]:53633 "EHLO
	mail-vc0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1754706AbaJGReK (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Tue, 7 Oct 2014 13:34:10 -0400
Date: Tue, 7 Oct 2014 13:34:04 -0400
From: Tejun Heo <tj@kernel.org>
To: "Luis R. Rodriguez" <mcgrof@suse.com>
Cc: "Luis R. Rodriguez" <mcgrof@do-not-panic.com>, gregkh@linuxfoundation.org,
        dmitry.torokhov@gmail.com, tiwai@suse.de, arjan@linux.intel.com,
        teg@jklm.no, rmilasan@suse.com, werner@suse.com, oleg@redhat.com,
        hare@suse.com, bpoirier@suse.de, santosh@chelsio.com, pmladek@suse.cz,
        dbueso@suse.com, linux-kernel@vger.kernel.org,
        Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
        Joseph Salisbury <joseph.salisbury@canonical.com>,
        Kay Sievers <kay@vrfy.org>,
        One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>,
        Tim Gardner <tim.gardner@canonical.com>,
        Pierre Fersing <pierre-fersing@pierref.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Nagalakshmi Nandigama <nagalakshmi.nandigama@avagotech.com>,
        Praveen Krishnamoorthy <praveen.krishnamoorthy@avagotech.com>,
        Sreekanth Reddy <sreekanth.reddy@avagotech.com>,
        Abhijit Mahajan <abhijit.mahajan@avagotech.com>,
        Casey Leedom <leedom@chelsio.com>,
        Hariprasad S <hariprasad@chelsio.com>,
        MPT-FusionLinux.pdl@avagotech.com, linux-scsi@vger.kernel.org,
        netdev@vger.kernel.org
Subject: Re: [PATCH v2 7/7] driver-core: add preferred async probe option for
 built-in and modules
Message-ID: <20141007173404.GB31328@mtj.dyndns.org>
References: <1412372683-2003-1-git-send-email-mcgrof@do-not-panic.com>
 <1412372683-2003-8-git-send-email-mcgrof@do-not-panic.com>
 <20141006201926.GF18303@htj.dyndns.org>
 <20141006203627.GZ14081@wotan.suse.de>
 <20141006210118.GG18303@htj.dyndns.org>
 <20141006231046.GD14081@wotan.suse.de>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20141006231046.GD14081@wotan.suse.de>
User-Agent: Mutt/1.5.23 (2014-03-12)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

Hello,

On Tue, Oct 07, 2014 at 01:10:46AM +0200, Luis R. Rodriguez wrote:
> On Mon, Oct 06, 2014 at 05:01:18PM -0400, Tejun Heo wrote:
> > For in-kernel stuff, we already have a clear
> > synchronization point where we already synchronize all async calls.
> > Shouldn't we be flushing these async probes there too?
> 
> This seems to be addressing if what I meant by prepared, "ready", so let
> me address this as I do think its important.
> 
> By async calls do you mean users of async_schedule()? I see it

Yes.

> also uses system_unbound_wq as well but I do not see anyone calling
> flush_workqueue(system_unbound_wq) on the kernel. We do use
> async_synchronize_full() on kernel_init() but that just waits.

But you can create a new workqueue and queue all the async probing
work items there and flush the workqueue right after
async_synchronize_full().

...
> bus.enable_kern_async=1 would still also serve as a helper for the driver core
> to figure out if it should use async probe then on modules if prefer_async_probe
> was enabled. Let me know if you figure out a way to avoid it.

Why do we need the choice at all?  It always should, no?

Thanks.

-- 
tejun