> -----Original Message----- > From: Darren Hart [mailto:dvhart@xxxxxxxxxxxxx] > Sent: Friday, November 3, 2017 7:53 PM > To: Limonciello, Mario <Mario_Limonciello@xxxxxxxx> > Cc: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>; LKML <linux- > kernel@xxxxxxxxxxxxxxx>; platform-driver-x86@xxxxxxxxxxxxxxx; > pali.rohar@xxxxxxxxx > 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
