From mboxrd@z Thu Jan 1 00:00:00 1970 From: Darren Hart Subject: Re: [PATCH] platform/x86: dell-*wmi*: Relay failed initial probe to dependent drivers Date: Thu, 2 Nov 2017 17:56:32 -0700 Message-ID: <20171103005632.GB7971@fury> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from bombadil.infradead.org ([65.50.211.133]:43702 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932398AbdKCA4e (ORCPT ); Thu, 2 Nov 2017 20:56:34 -0400 Content-Disposition: inline In-Reply-To: Sender: platform-driver-x86-owner@vger.kernel.org List-ID: To: Mario Limonciello Cc: Andy Shevchenko , LKML , platform-driver-x86@vger.kernel.org, pali.rohar@gmail.com On Wed, Nov 01, 2017 at 02:28:21PM -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 > should still be verified to return success values otherwise deferred > probing be used. > > Signed-off-by: Mario Limonciello > diff --git a/drivers/platform/x86/dell-wmi-descriptor.c b/drivers/platform/x86/dell-wmi-descriptor.c > index 3204c408e261..33c6c7d66f8c 100644 > --- a/drivers/platform/x86/dell-wmi-descriptor.c > +++ b/drivers/platform/x86/dell-wmi-descriptor.c > @@ -26,9 +26,16 @@ struct descriptor_priv { > u32 interface_version; > u32 size; > }; > +static int descriptor_valid; This initializes to 0, which I believe creates an odd race window between when this init is called and when the first driver calls dell_wmi_get_descriptor_valid(). Seems like initializing to -EPROBE_DEFER here in the declaration would be a better right approach. -- Darren Hart VMware Open Source Technology Center