From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753965AbbFSWyx (ORCPT ); Fri, 19 Jun 2015 18:54:53 -0400 Received: from v094114.home.net.pl ([79.96.170.134]:56135 "HELO v094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1752194AbbFSWyo (ORCPT ); Fri, 19 Jun 2015 18:54:44 -0400 From: "Rafael J. Wysocki" To: Tomeu Vizoso Cc: "linux-arm-kernel@lists.infradead.org" , Alexander Holler , Alexandre Courbot , Andrzej Hajda , Arnd Bergmann , Dmitry Torokhov , Grant Likely , Greg Kroah-Hartman , Ian Campbell , Javier Martinez Canillas , Krzysztof Kozlowski , Kumar Gala , Len Brown , Linus Walleij , "linux-kernel@vger.kernel.org" , Lv Zheng , Mark Brown , Mark Rutland , Pawel Moll , Robert Moore , Rob Herring , Russell King , Stephen Warren , Terje =?ISO-8859-1?Q?Bergstr=F6m?= , Thierry Reding Subject: Re: [PATCH 02/13] driver-core: defer all probes until late_initcall Date: Sat, 20 Jun 2015 01:20:46 +0200 Message-ID: <1585940.7Lfuk0LdBK@vostro.rjw.lan> User-Agent: KMail/4.11.5 (Linux/4.1.0-rc5+; KDE/4.11.5; x86_64; ; ) In-Reply-To: References: <1434548543-22949-1-git-send-email-tomeu.vizoso@collabora.com> <2834968.DlsDAmbXkG@vostro.rjw.lan> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Friday, June 19, 2015 03:36:46 PM Tomeu Vizoso wrote: > On 18 June 2015 at 23:50, Rafael J. Wysocki wrote: > > On Wednesday, June 17, 2015 03:42:12 PM Tomeu Vizoso wrote: > >> To decrease the chances of devices deferring their probes because of > >> dependencies not having probed yet because of their drivers not having > >> registered yet, delay all probing until the late initcall level. > >> > >> This will allow us to avoid deferred probes completely later by probing > >> dependencies on demand, or by probing them in dependency order. > >> > >> Signed-off-by: Tomeu Vizoso > >> --- > >> drivers/base/dd.c | 8 +++++++- > >> 1 file changed, 7 insertions(+), 1 deletion(-) > >> > >> diff --git a/drivers/base/dd.c b/drivers/base/dd.c > >> index a638bbb..18438aa 100644 > >> --- a/drivers/base/dd.c > >> +++ b/drivers/base/dd.c > >> @@ -407,6 +407,12 @@ int driver_probe_device(struct device_driver *drv, struct device *dev) > >> if (!device_is_registered(dev)) > >> return -ENODEV; > >> > >> + /* Defer all probes until we start processing the queue */ > >> + if (!driver_deferred_probe_enable) { > >> + driver_deferred_probe_add(dev); > > > > Do I think correctly that this will effectively force everybody to use deferred > > probing? > > Guess it depends on the meaning of "using deferred probing". It will > defer the probe of the first device to late_initcall (which will > happen much earlier in time than before), but afterwards all built-in > drivers will be available and depending on the order in which we try > to probe devices, none may actually ask to defer its probe. So this will break things like the PNP system driver which relies on probing stuff at the fs_initcall stage for correctness. It may also break other things with similar assumptions. -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in Please read the FAQ at http://www.tux.org/lkml/ From mboxrd@z Thu Jan 1 00:00:00 1970 From: rjw@rjwysocki.net (Rafael J. Wysocki) Date: Sat, 20 Jun 2015 01:20:46 +0200 Subject: [PATCH 02/13] driver-core: defer all probes until late_initcall In-Reply-To: References: <1434548543-22949-1-git-send-email-tomeu.vizoso@collabora.com> <2834968.DlsDAmbXkG@vostro.rjw.lan> Message-ID: <1585940.7Lfuk0LdBK@vostro.rjw.lan> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Friday, June 19, 2015 03:36:46 PM Tomeu Vizoso wrote: > On 18 June 2015 at 23:50, Rafael J. Wysocki wrote: > > On Wednesday, June 17, 2015 03:42:12 PM Tomeu Vizoso wrote: > >> To decrease the chances of devices deferring their probes because of > >> dependencies not having probed yet because of their drivers not having > >> registered yet, delay all probing until the late initcall level. > >> > >> This will allow us to avoid deferred probes completely later by probing > >> dependencies on demand, or by probing them in dependency order. > >> > >> Signed-off-by: Tomeu Vizoso > >> --- > >> drivers/base/dd.c | 8 +++++++- > >> 1 file changed, 7 insertions(+), 1 deletion(-) > >> > >> diff --git a/drivers/base/dd.c b/drivers/base/dd.c > >> index a638bbb..18438aa 100644 > >> --- a/drivers/base/dd.c > >> +++ b/drivers/base/dd.c > >> @@ -407,6 +407,12 @@ int driver_probe_device(struct device_driver *drv, struct device *dev) > >> if (!device_is_registered(dev)) > >> return -ENODEV; > >> > >> + /* Defer all probes until we start processing the queue */ > >> + if (!driver_deferred_probe_enable) { > >> + driver_deferred_probe_add(dev); > > > > Do I think correctly that this will effectively force everybody to use deferred > > probing? > > Guess it depends on the meaning of "using deferred probing". It will > defer the probe of the first device to late_initcall (which will > happen much earlier in time than before), but afterwards all built-in > drivers will be available and depending on the order in which we try > to probe devices, none may actually ask to defer its probe. So this will break things like the PNP system driver which relies on probing stuff at the fs_initcall stage for correctness. It may also break other things with similar assumptions. -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center.