> -----Original Message----- > From: Pali Rohár [mailto:pali.rohar@xxxxxxxxx] > Sent: Tuesday, October 10, 2017 3:18 AM > To: Limonciello, Mario <Mario_Limonciello@xxxxxxxx> > Cc: dvhart@xxxxxxxxxxxxx; Andy Shevchenko <andy.shevchenko@xxxxxxxxx>; > LKML <linux-kernel@xxxxxxxxxxxxxxx>; platform-driver-x86@xxxxxxxxxxxxxxx; > Andy Lutomirski <luto@xxxxxxxxxx>; quasisec@xxxxxxxxxx; rjw@xxxxxxxxxxxxx; > mjg59@xxxxxxxxxx; hch@xxxxxx; Greg KH <greg@xxxxxxxxx> > 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 > pali.rohar@xxxxxxxxx
