From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932152AbdKDDZI (ORCPT ); Fri, 3 Nov 2017 23:25:08 -0400 Received: from esa2.dell-outbound.iphmx.com ([68.232.149.220]:33544 "EHLO esa2.dell-outbound.iphmx.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751216AbdKDDZG (ORCPT ); Fri, 3 Nov 2017 23:25:06 -0400 From: X-LoopCount0: from 10.166.132.189 X-IronPort-AV: E=Sophos;i="5.44,339,1505797200"; d="scan'208";a="83063753" X-DLP: DLP_GlobalPCIDSS To: CC: , , , Subject: RE: [PATCH 2/2] platform/x86: dell-*wmi*: Relay failed initial probe to dependent drivers Thread-Topic: [PATCH 2/2] platform/x86: dell-*wmi*: Relay failed initial probe to dependent drivers Thread-Index: AQHTVQdWDK9lNIlgV0eTe61C/swOtqMDjm+w Date: Sat, 4 Nov 2017 03:25:04 +0000 Message-ID: <41ef814bda1d41ab87880ab569aa48b3@ausx13mpc120.AMER.DELL.COM> References: <6312b76d08d3b6b5562c773fce8e13d85036ddd5.1509725778.git.mario.limonciello@dell.com> <20171104005327.GC24317@fury> In-Reply-To: <20171104005327.GC24317@fury> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.143.242.75] Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by nfs id vA43PGY8008507 > -----Original Message----- > From: Darren Hart [mailto:dvhart@infradead.org] > Sent: Friday, November 3, 2017 7:53 PM > To: Limonciello, Mario > Cc: Andy Shevchenko ; LKML kernel@vger.kernel.org>; platform-driver-x86@vger.kernel.org; > pali.rohar@gmail.com > Subject: Re: [PATCH 2/2] platform/x86: dell-*wmi*: Relay failed initial probe to > dependent drivers > > On Fri, Nov 03, 2017 at 11:27:22AM -0500, Mario Limonciello wrote: > > dell-wmi and dell-smbios-wmi are dependent upon dell-wmi-descriptor > > finishing probe successfully to probe themselves. > > > > Currently if dell-wmi-descriptor fails probing in a non-recoverable way > > (such as invalid header) dell-wmi and dell-smbios-wmi will continue to > > try to redo probing due to deferred probing. > > > > To solve this have the dependent drivers query the dell-wmi-descriptor > > driver whether the descriptor has been determined valid. The possible > > results are: > > -EPROBE_DEFER: Descriptor not yet probed, dependent driver should wait > > and use deferred probing > > < 0: Descriptor probed, invalid. Dependent driver should return an > > error. > > 0: Successful descriptor probe, dependent driver can continue > > > > Successful descriptor probe still doesn't mean that the descriptor driver > > is necessarily bound at the time of initialization of dependent driver. > > Userspace can unbind the driver, so all methods used from driver > > Userspace shouldn't be able to remove the dell-wmi-descriptor driver if a > dependent driver is loaded. It isn't clear to me in which scenario we encounter > this problem ?? Userspace can however unbind a bound GUID. When this happens getting the interface version and size will both fail. > > > > should still be verified to return success values otherwise deferred > > probing be used. > > The part after "otherwise" is breaking my English parser... > > Should this read: "Userspace can unbind the driver, so all methods used from the > driver should still be verified to return successful values, falling back to > deferred probing in case of failure." ?? Yeah that's clearer and correct. > > > diff --git a/drivers/platform/x86/dell-wmi-descriptor.h > b/drivers/platform/x86/dell-wmi-descriptor.h > > index 5f7b69c2c83a..776cddd5e135 100644 > > --- a/drivers/platform/x86/dell-wmi-descriptor.h > > +++ b/drivers/platform/x86/dell-wmi-descriptor.h > > @@ -15,6 +15,13 @@ > > > > #define DELL_WMI_DESCRIPTOR_GUID "8D9DDCBC-A997-11DA-B012- > B622A1EF5492" > > > > +/* possible return values: > > This should trigger a checkpatch error, but doesn't. Huh. For everything but > "net", comment blocks should start with /* and not following text. > OK. > /* > * First line. > * Second line. > */ > > A nit, and I can clean up if no changes are deemed necessary here. > > > + * -EPROBE_DEFER: probing for dell-wmi-descriptor not yet run > > + * 0: valid descriptor, successfully probed > > + * < 0: invalid descriptor, don't probe dependent devices > > + */ > > -- > Darren Hart > VMware Open Source Technology Center