From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754367AbdKAITc (ORCPT ); Wed, 1 Nov 2017 04:19:32 -0400 Received: from mail-wr0-f194.google.com ([209.85.128.194]:54083 "EHLO mail-wr0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754333AbdKAIT2 (ORCPT ); Wed, 1 Nov 2017 04:19:28 -0400 X-Google-Smtp-Source: ABhQp+SWxBxvqU9wkiEgxKqAl6rtw8sULblqDyuF3uYx+XzTzw7hKkL+Ccy5uLgvT1wO6ylywFEvuw== Date: Wed, 1 Nov 2017 09:19:25 +0100 From: Pali =?utf-8?B?Um9ow6Fy?= To: Darren Hart Cc: Mario.Limonciello@dell.com, andy.shevchenko@gmail.com, linux-kernel@vger.kernel.org, platform-driver-x86@vger.kernel.org, luto@kernel.org, quasisec@google.com, rjw@rjwysocki.net, mjg59@google.com, hch@lst.de, greg@kroah.com, gnomes@lxorguk.ukuu.org.uk Subject: Re: [PATCH v11 05/15] platform/x86: dell-wmi-descriptor: split WMI descriptor into it's own driver Message-ID: <20171101081925.66gca5sqtqcnpksu@pali> References: <20171030114652.kopuffflshq2ates@pali> <27e2d166f2ce461fb025ebf06a284d01@ausx13mpc124.AMER.DELL.COM> <20171031233146.GA5787@fury> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20171031233146.GA5787@fury> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday 31 October 2017 16:31:46 Darren Hart wrote: > On Mon, Oct 30, 2017 at 01:32:57PM +0000, Mario.Limonciello@dell.com wrote: > > > > > > > -----Original Message----- > > > From: Pali Rohár [mailto:pali.rohar@gmail.com] > > > Sent: Monday, October 30, 2017 6:47 AM > > > To: Limonciello, Mario > > > Cc: dvhart@infradead.org; Andy Shevchenko ; > > > LKML ; platform-driver-x86@vger.kernel.org; Andy > > > Lutomirski ; quasisec@google.com; rjw@rjwysocki.net; > > > mjg59@google.com; hch@lst.de; Greg KH ; Alan Cox > > > > > > Subject: Re: [PATCH v11 05/15] platform/x86: dell-wmi-descriptor: split WMI > > > descriptor into it's own driver > > > > > > On Friday 20 October 2017 12:40:20 Mario Limonciello wrote: > > > > diff --git a/drivers/platform/x86/dell-wmi-descriptor.c > > > b/drivers/platform/x86/dell-wmi-descriptor.c > > > > new file mode 100644 > > > > index 000000000000..3204c408e261 > > > > --- /dev/null > > > > +++ b/drivers/platform/x86/dell-wmi-descriptor.c > > > > > > This dell-wmi-descriptor.c looks good now! > > > > > > > diff --git a/drivers/platform/x86/dell-wmi-descriptor.h > > > b/drivers/platform/x86/dell-wmi-descriptor.h > > > > new file mode 100644 > > > > index 000000000000..5f7b69c2c83a > > > > --- /dev/null > > > > +++ b/drivers/platform/x86/dell-wmi-descriptor.h > > > > @@ -721,7 +652,9 @@ static int dell_wmi_events_set_enabled(bool enable) > > > > static int dell_wmi_probe(struct wmi_device *wdev) > > > > { > > > > struct dell_wmi_priv *priv; > > > > - int err; > > > > + > > > > + if (!wmi_has_guid(DELL_WMI_DESCRIPTOR_GUID)) > > > > + return -ENODEV; > > > > > > > > priv = devm_kzalloc( > > > > &wdev->dev, sizeof(struct dell_wmi_priv), GFP_KERNEL); > > > > @@ -729,9 +662,8 @@ static int dell_wmi_probe(struct wmi_device *wdev) > > > > return -ENOMEM; > > > > dev_set_drvdata(&wdev->dev, priv); > > > > > > > > - err = dell_wmi_check_descriptor_buffer(wdev); > > > > - if (err) > > > > - return err; > > > > + if (!dell_wmi_get_interface_version(&priv->interface_version)) > > > > + return -EPROBE_DEFER; > > > > > > But here is still a problem. You added check that > > > DELL_WMI_DESCRIPTOR_GUID exists in APCI table, but it does not mean that > > > probe method of dell-wmi-descriptor cannot fail. > > > > > > With PROBE_DEFER, dell_wmi_probe function would be called later again > > > and again, even when probing dell-wmi-descriptor failed and so dell-wmi > > > in this case cannot work. > > > > > > > Yes it's possible that probe method can fail, but it depends on the reason for > > failure if it will fail again later. For example if not enough memory, it may work > > later. Or maybe user manually unbound from GUID, should continue to try until > > it's bound again. > > > > So in short, I believe this is the correct behavior to adopt. > > In this case, I believe the synchronous request_module("dell-wmi-descriptor") > would provide the desired result. The exit status doesn't even need to be > checked. If that is successful, and the interface_version still returns false, > then it can be considered an error and we can exit. If it fails, the > interface_version will return false, and it is also an error. > > This can be easily added as a single patch on top of this series: > > diff --git a/drivers/platform/x86/dell-wmi.c b/drivers/platform/x86/dell-wmi.c > index dcfa5de..964ca54 100644 > --- a/drivers/platform/x86/dell-wmi.c > +++ b/drivers/platform/x86/dell-wmi.c > @@ -665,8 +665,9 @@ static int dell_wmi_probe(struct wmi_device *wdev) > return -ENOMEM; > dev_set_drvdata(&wdev->dev, priv); > > + request_module("dell-wmi-descriptor"); > if (!dell_wmi_get_interface_version(&priv->interface_version)) > - return -EPROBE_DEFER; > + return -ENODEV; > > return dell_wmi_input_setup(wdev); > } > > Pali, I believe this addresses your concern? I'm not sure what happen if both drivers are statically linked into vmlinuz and dell-wmi probe method would be called before dell-wmi-descriptor method. What is doing request_module when requested module is statically linked into vmlinuz? -- Pali Rohár pali.rohar@gmail.com