> -----Original Message-----
> From: Pali Rohár [mailto:[email protected]]
> Sent: Tuesday, October 10, 2017 3:18 AM
> To: Limonciello, Mario <[email protected]>
> Cc: [email protected]; Andy Shevchenko <[email protected]>;
> LKML <[email protected]>; [email protected];
> Andy Lutomirski <[email protected]>; [email protected]; [email protected];
> [email protected]; [email protected]; Greg KH <[email protected]>
> Subject: Re: [PATCH v6 05/14] platform/x86: dell-wmi-descriptor: split WMI
> descriptor into it's own driver
>
> On Monday 09 October 2017 17:51:43 Mario Limonciello wrote:
> > +bool dell_wmi_get_interface_version(u32 *version)
> > +{
> > + struct descriptor_priv *priv;
> > +
> > + priv = list_first_entry_or_null(&wmi_list,
> > + struct descriptor_priv,
> > + list);
> > + if (!priv)
> > + return false;
>
> This introduce race condition. In case callee of this function is
> executed before binding 8D9DDCBC-A997-11DA-B012-B622A1EF5492 WMI device
> into this dell-wmi-descriptor driver, then this function
> dell_wmi_get_interface_version() returns false. Even it is running on
> supported machine.
>
> Loading of modulus and also binding devices to drivers (registered by
> modules) is is asynchronous.
>
I suppose you're right, module dependency ordering doesn't necessarily
guarantee binding. I'll add in some deferred probing and binding checking.
> In case everything is linked into vmlinux binary, this problem could
> happen too. Binding & initialization of WMI device to this driver can be
> postponed and callee (dell-wmi) would get false.
>
> > + *version = priv->interface_version;
> > + return true;
> > +}
> > +EXPORT_SYMBOL_GPL(dell_wmi_get_interface_version);
> > +
> > +bool dell_wmi_get_size(u32 *size)
> > +{
> > + struct descriptor_priv *priv;
> > +
> > + priv = list_first_entry_or_null(&wmi_list,
> > + struct descriptor_priv,
> > + list);
> > + if (!priv)
> > + return false;
>
> And same there.
>
> > + *size = priv->size;
> > + return true;
> > +}
> > +EXPORT_SYMBOL_GPL(dell_wmi_get_size);
>
> --
> Pali Rohár
> [email protected]
