On 7/31/20 3:56 PM, Barnabás Pőcze wrote:
2020. július 31., péntek 22:21 keltezéssel, Daniel Dadap <ddadap@xxxxxxxxxx> írta:If a driver registers with WMI, and none of the GUIDs in its ID table is present on the system, then that driver will not be probed and automatically loaded. However, it is still possible to load such a driver explicitly on a system which doesn't include the relevant hardware. Update wmi_driver_register to test for the presence of at least one GUID from the driver's ID table at driver registration time, and fail registration if none are found. Signed-off-by: Daniel Dadap <ddadap@xxxxxxxxxx> --- drivers/platform/x86/wmi.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/drivers/platform/x86/wmi.c b/drivers/platform/x86/wmi.c index 941739db7199..19aa23d1cf8e 100644 --- a/drivers/platform/x86/wmi.c +++ b/drivers/platform/x86/wmi.c @@ -130,6 +130,21 @@ static bool find_guid(const char *guid_string, struct wmi_block **out) return false; } +static bool find_driver_guid(const struct wmi_driver *wdriver) +{ + const struct wmi_device_id *id; + + if (wdriver == NULL) + return false; + + for (id = wdriver->id_table; *id->guid_string; id++) { + if (find_guid(id->guid_string, NULL)) + return true; + } + + return false; +} + static const void *find_guid_context(struct wmi_block *wblock, struct wmi_driver *wdriver) { @@ -1419,6 +1434,9 @@ static int acpi_wmi_probe(struct platform_device *device) int __must_check __wmi_driver_register(struct wmi_driver *driver, struct module *owner) { + if (!find_driver_guid(driver)) + return -ENODEV; + driver->driver.owner = owner; driver->driver.bus = &wmi_bus_type; -- 2.18.4Can you elaborate as to why this change in behaviour of the wmi driver is needed? If I understand it correctly you want to prevent WMI drivers from successfully loading when there are no matching GUIDs. Is that correct?
Currently, a driver that registers with WMI can be explicitly loaded, even on a system that lacks the relevant hardware. It's not a huge deal if this happens, since most people won't bother explicitly loading a driver their system can't use, and since the probe routine will never be called, the module just sits around uselessly loaded into the kernel. I discovered this behavior when testing the version of the patch reworked to register with WMI, and thought it would be nice to not allow useless modules to be loaded, but if anybody disagrees with this change, it's certainly not essential, and I'm happy to leave the behavior the way it currently is.
Barnabás Pőcze
