Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751527AbaG1Q7Z (ORCPT ); Mon, 28 Jul 2014 12:59:25 -0400 Received: from cantor2.suse.de ([195.135.220.15]:57541 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750701AbaG1Q7X (ORCPT ); Mon, 28 Jul 2014 12:59:23 -0400 Date: Mon, 28 Jul 2014 18:59:20 +0200 From: "Luis R. Rodriguez" To: Yuval Mintz Cc: "Luis R. Rodriguez" , "gregkh@linuxfoundation.org" , linux-kernel , Tetsuo Handa , Joseph Salisbury , Kay Sievers , One Thousand Gnomes , Tim Gardner , Pierre Fersing , Andrew Morton , Oleg Nesterov , Benjamin Poirier , Nagalakshmi Nandigama , Praveen Krishnamoorthy , Sreekanth Reddy , Abhijit Mahajan , Hariprasad S , Santosh Rastapur , "MPT-FusionLinux.pdl@avagotech.com" , linux-scsi , netdev Subject: Re: [PATCH 1/3] driver core: enable drivers to use deferred probe from init Message-ID: <20140728165920.GF21930@wotan.suse.de> References: <1406558067-25308-1-git-send-email-mcgrof@do-not-panic.com> <20140728153811.GD21930@wotan.suse.de> <20140728165248.GE21930@wotan.suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140728165248.GE21930@wotan.suse.de> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 28, 2014 at 06:52:48PM +0200, Luis R. Rodriguez wrote: > On Mon, Jul 28, 2014 at 03:46:32PM +0000, Yuval Mintz wrote: > > > Subject: Re: [PATCH 1/3] driver core: enable drivers to use deferred probe from > > > init > > > > > > On Mon, Jul 28, 2014 at 03:12:11PM +0000, Yuval Mintz wrote: > > > > Perhaps this is a silly question, but what guarantees that the > > > > deferred probe list will actually be triggered, e.g., in case the > > > > delayed device is the last device in the system? > > > > > > The dev->init_delayed_probe is used to ensure that we'd add the device to the > > > deferred probe list once making this a per device thing if the driver has the field > > > delay_probe set to true. This technically also allows this to be a per device thing > > > so with some more work we could enable drivers to only enable this for specific > > > devices but at this point this did not seem required. > > > > Sorry for not being clear, but I didn't meant 'what guarantees that the device > > will be added to the deferred probe', but rather what guarantees that the > > deferred workqueue will be scheduled. > > > > To the best of my knowledge the deferring mechanism works only if one device > > is dependent upon another, e.g., for Multi-function devices where one device > > probe is dependent upon the others - which are soon-to-be probed. > > The workqueue will be kicked when driver_deferred_probe_trigger() gets > poked, we do that in the late_initcall(deferred_probe_initcall), it > also gets flushed there with a flush_workqueue(deferred_wq). But come to think of it that will work well for devices already plugged in so indeed I think that driver_deferred_probe_add() needs a check added for for if (!driver_deferred_probe_enable) then we have to driver_deferred_probe_trigger(). The driver_deferred_probe_enable is set to false upon init, but later on late init it gets set to true so with that check we'd only generate the trigger after late init call. I can fold that in the v2. Luis -- 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/