> -----Original Message----- > From: Darren Hart [mailto:dvhart@xxxxxxxxxxxxx] > Sent: Thursday, November 2, 2017 7:57 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] platform/x86: dell-*wmi*: Relay failed initial probe to > dependent drivers > > 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 <mario.limonciello@xxxxxxxx> > > > 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. > > -- Thanks, good catch. I'll adjust.
