RE: [PATCH] platform/x86: dell-wmi-sysman: correct an initialization failure

[Limonciello, Mario]

> -----Original Message-----
> From: mark gross <mgross@xxxxxxxxxxxxxxx>
> Sent: Thursday, February 18, 2021 16:49
> To: Limonciello, Mario
> Cc: Hans De Goede; Mark Gross; LKML; platform-driver-x86@xxxxxxxxxxxxxxx;
> Bharathi, Divya; Alexander Naumann
> Subject: Re: [PATCH] platform/x86: dell-wmi-sysman: correct an initialization
> failure
> 
> 
> [EXTERNAL EMAIL]
> 
> On Thu, Feb 18, 2021 at 01:17:23PM -0600, Mario Limonciello wrote:
> > On Dell systems that don't support this interface the module is
> > mistakingly returning error code "0", when it should be returning
> > -ENODEV.  Correct a logic error to guarantee the correct return code.
> >
> > Cc: Divya Bharathi <Divya_Bharathi@xxxxxxxx>
> > Reported-by: Alexander Naumann <alexandernaumann@xxxxxx>
> > Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxxx>
> > ---
> >  drivers/platform/x86/dell-wmi-sysman/biosattr-interface.c     | 4 +++-
> >  drivers/platform/x86/dell-wmi-sysman/passwordattr-interface.c | 4 +++-
> >  drivers/platform/x86/dell-wmi-sysman/sysman.c                 | 4 ++--
> >  3 files changed, 8 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/platform/x86/dell-wmi-sysman/biosattr-interface.c
> b/drivers/platform/x86/dell-wmi-sysman/biosattr-interface.c
> > index f95d8ddace5a..8d59f81f9db4 100644
> > --- a/drivers/platform/x86/dell-wmi-sysman/biosattr-interface.c
> > +++ b/drivers/platform/x86/dell-wmi-sysman/biosattr-interface.c
> > @@ -175,7 +175,9 @@ static struct wmi_driver bios_attr_set_interface_driver
> = {
> >
> >  int init_bios_attr_set_interface(void)
> >  {
> > -	return wmi_driver_register(&bios_attr_set_interface_driver);
> > +	int ret = wmi_driver_register(&bios_attr_set_interface_driver);
> I have to ask if the propper fix should be in wmi_driver_register

Do you mean something like this?

diff --git a/drivers/platform/x86/wmi.c b/drivers/platform/x86/wmi.c
index c669676ea8e8..89d04c5e3ab9 100644
--- a/drivers/platform/x86/wmi.c
+++ b/drivers/platform/x86/wmi.c
@@ -1415,6 +1415,11 @@ static int acpi_wmi_probe(struct platform_device *device)
 int __must_check __wmi_driver_register(struct wmi_driver *driver,
                                       struct module *owner)
 {
+       const struct wmi_device_id *id = driver->id_table;
+
+       if (!wmi_has_guid(id->guid_string))
+               return -ENODEV;
+
        driver->driver.owner = owner;
        driver->driver.bus = &wmi_bus_type;

> > +
> > +	return wmi_priv.bios_attr_wdev ? ret : -ENODEV;
> Also, is there any point to call wmi_driver_register if returning -ENODEV?
> i.e. should the call to driver register be wrapped in a test for
> bios_atter_wdev?

With some bus types it probably makes sense to register the driver whether or
not the device is present.  With the wmi bus it's fixed at bootup.

> 
> 
> >  }
> >
> >  void exit_bios_attr_set_interface(void)
> > diff --git a/drivers/platform/x86/dell-wmi-sysman/passwordattr-interface.c
> b/drivers/platform/x86/dell-wmi-sysman/passwordattr-interface.c
> > index 5780b4d94759..bf449dc5ff47 100644
> > --- a/drivers/platform/x86/dell-wmi-sysman/passwordattr-interface.c
> > +++ b/drivers/platform/x86/dell-wmi-sysman/passwordattr-interface.c
> > @@ -142,7 +142,9 @@ static struct wmi_driver bios_attr_pass_interface_driver
> = {
> >
> >  int init_bios_attr_pass_interface(void)
> >  {
> > -	return wmi_driver_register(&bios_attr_pass_interface_driver);
> > +	int ret = wmi_driver_register(&bios_attr_pass_interface_driver);
> > +
> > +	return wmi_priv.password_attr_wdev ? ret : -ENODEV;
> same comments as above only for password_atter_wdev.
> 
> --mark
> 
> >  }
> >
> >  void exit_bios_attr_pass_interface(void)
> > diff --git a/drivers/platform/x86/dell-wmi-sysman/sysman.c
> b/drivers/platform/x86/dell-wmi-sysman/sysman.c
> > index cb81010ba1a2..d9ad0e83b66f 100644
> > --- a/drivers/platform/x86/dell-wmi-sysman/sysman.c
> > +++ b/drivers/platform/x86/dell-wmi-sysman/sysman.c
> > @@ -513,13 +513,13 @@ static int __init sysman_init(void)
> >  	}
> >
> >  	ret = init_bios_attr_set_interface();
> > -	if (ret || !wmi_priv.bios_attr_wdev) {
> > +	if (ret) {
> >  		pr_debug("failed to initialize set interface\n");
> >  		goto fail_set_interface;
> >  	}
> >
> >  	ret = init_bios_attr_pass_interface();
> > -	if (ret || !wmi_priv.password_attr_wdev) {
> > +	if (ret) {
> >  		pr_debug("failed to initialize pass interface\n");
> >  		goto fail_pass_interface;
> >  	}
> > --
> > 2.25.1
> >