Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752160AbbGIAnc (ORCPT ); Wed, 8 Jul 2015 20:43:32 -0400 Received: from mail-wg0-f41.google.com ([74.125.82.41]:36756 "EHLO mail-wg0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751432AbbGIAnY (ORCPT ); Wed, 8 Jul 2015 20:43:24 -0400 MIME-Version: 1.0 In-Reply-To: <20150706233846.GF32140@dtor-ws> References: <20150706233846.GF32140@dtor-ws> Date: Wed, 8 Jul 2015 17:43:23 -0700 Message-ID: Subject: Re: [PATCH 2/8] driver-core: add asynchronous probing support for drivers From: Dan Williams To: Dmitry Torokhov Cc: "Luis R. Rodriguez" , Tom Gundersen , Greg Kroah-Hartman , Tejun Heo , Linux Kernel Mailing List , Arjan van de Ven , Rusty Russell , Olof Johansson , Tetsuo Handa Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1190 Lines: 24 On Mon, Jul 6, 2015 at 4:38 PM, Dmitry Torokhov wrote: > On Sat, Jul 04, 2015 at 07:09:19AM -0700, Dan Williams wrote: >> The problem I ran into was needing to remove devices that still had >> yet to be probed and not being able to use registration completion vs >> the device_lock() to effectively synchronize the sub-system. > > Why do you need to "synchronize the sub-system"? The asynchronous > probing should be transparent to the driver. Just unregister the device > (or the driver) and driver core will ensure that probe() is not in > flight. Async registration is indeed transparent to the driver. The primary need to "flush registration" is the case of "region" devices that reference a set of NVDIMM devices. A region device requires all related NVDIMMs to be active before the region can be enabled. I'll look into a more concrete example of the tradeoffs between asynchronous probing vs registration. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/