Re: Plans for mISDN? Was: [PATCH 00/14] [ISDN] ...

[Bodo Eggert]

Andi Kleen <andi@xxxxxxxxxxxxxx> wrote:

>> we were talking about the load order. This will solve the load order,
>> but if we have races like the kind you described, then the whole mISDN
>> design is broken.
> 
> It's more a generic problem of the module code.

It's a problem of not enough synchronisation before a module load completes.

If a module provides an interface, but needs some time after being load to
initialize, it obviously MUST provide a way to wait for it. Since you'll
need some i-need-module-foo functions anyway, why not: (bar needs foo)

-foo.c---
DECLARE_COMPLETION(init_complete); /* static? */
module_foo_init_async() {
        ...
        void complete_all(&init_complete);
}

void usemod_foo()
{
        wait_for_completion(&init_complete);
}
EXPORT_SYMBOL(usemod_foo)

-bar.c---
DECLARE_COMPLETION(init_complete);
module_bar_init_async() {
        usemod_foo();
        ...
        void complete_all(&init_complete);
}

void usemod_bar()
{
        wait_for_completion(&init_complete);
}
EXPORT_SYMBOL(usemod_bar)


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