From: <Mario.Limonciello@dell.com> To: <dvhart@infradead.org> Cc: <andy.shevchenko@gmail.com>, <linux-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 Date: Sat, 4 Nov 2017 03:25:04 +0000 [thread overview] Message-ID: <41ef814bda1d41ab87880ab569aa48b3@ausx13mpc120.AMER.DELL.COM> (raw) In-Reply-To: <20171104005327.GC24317@fury> > -----Original Message----- > From: Darren Hart [mailto:dvhart@infradead.org] > Sent: Friday, November 3, 2017 7:53 PM > To: Limonciello, Mario <Mario_Limonciello@Dell.com> > Cc: Andy Shevchenko <andy.shevchenko@gmail.com>; LKML <linux- > 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
WARNING: multiple messages have this Message-ID (diff)
From: <Mario.Limonciello@dell.com> To: dvhart@infradead.org Cc: andy.shevchenko@gmail.com, linux-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 Date: Sat, 4 Nov 2017 03:25:04 +0000 [thread overview] Message-ID: <41ef814bda1d41ab87880ab569aa48b3@ausx13mpc120.AMER.DELL.COM> (raw) In-Reply-To: <20171104005327.GC24317@fury> > -----Original Message----- > From: Darren Hart [mailto:dvhart@infradead.org] > Sent: Friday, November 3, 2017 7:53 PM > To: Limonciello, Mario <Mario_Limonciello@Dell.com> > Cc: Andy Shevchenko <andy.shevchenko@gmail.com>; LKML <linux- > 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
next prev parent reply other threads:[~2017-11-04 3:25 UTC|newest] Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-11-03 16:27 [PATCH 0/2] Account for uncorrectable failures in probing Mario Limonciello 2017-11-03 16:27 ` [PATCH 1/2] platform/x86: dell-wmi-descriptor: check if memory was allocated Mario Limonciello 2017-11-09 12:07 ` Pali Rohár 2017-11-03 16:27 ` [PATCH 2/2] platform/x86: dell-*wmi*: Relay failed initial probe to dependent drivers Mario Limonciello 2017-11-04 0:53 ` Darren Hart 2017-11-04 3:25 ` Mario.Limonciello [this message] 2017-11-04 3:25 ` Mario.Limonciello 2017-11-09 16:02 ` Pali Rohár 2017-11-09 16:13 ` Mario.Limonciello 2017-11-09 16:13 ` Mario.Limonciello 2017-11-09 17:28 ` Pali Rohár 2017-11-09 17:34 ` Mario.Limonciello 2017-11-09 17:34 ` Mario.Limonciello 2017-11-09 17:52 ` Darren Hart 2017-11-07 16:17 ` [PATCH 0/2] Account for uncorrectable failures in probing Mario.Limonciello 2017-11-07 16:17 ` Mario.Limonciello
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