Previously we were loading kernel modules on all device events save
for "remove". With the introduction of KOBJ_BIND/KOBJ_UNBIND this causes
issues, as driver modules that have devices bound to their drivers get
immediately reloaded, and it appears to the user that module unloading
does not work.
Let's change the rules to only load modules on "add" events instead.
On Sat, Jul 20, 2013 at 12:56 PM, Rafael J. Wysocki <rjw@sisk.pl> wrote:
> After a recent change present in 3.11-rc1 there is a driver, called processor,
> that can be bound to the CPU devices whose sysfs directories are located under
> /sys/devices/system/cpu/. A side effect of this is that, after the driver has
> been bound to those devices, the kernel adds DRIVER=processor to ENV for CPU
> uevents and they don't match the default rule for autoloading modules matching
> MODALIAS:
>
> DRIVER!="?*", ENV{MODALIAS}=="?*", IMPORT{builtin}="kmod load $env{MODALIAS}"
>
> any more. However, there are some modules whose module aliases match specific
> CPU features through the modalias string and those modules should be loaded
> automatically if a compatible CPU is present. Yet, with the processor driver
> bound to the CPU devices the above rule is not sufficient for that, so we need
> a new default udev rule allowing those modules to be autoloaded even if the
> CPU devices have drivers.
The 'kmod' builtin, like the 'firmware' and 'uaccess' builtins, does not set
any variables, so don't use IMPORT.
Notice that this changes the behaviour slightly: the processing of subsequent
rules for the event that loads a module will no longer wait for the module
loading to finish. This is not expected to cause any problems, but we should
keep an eye on it.
Dmitry Torokhov