> I was going through try_module_get function in include/linux/module.h file
> (2.6.22 stock kernel) - which is like:
>
> -----
> static inline int try_module_get(struct module *module){
> int ret = 1; <--- error case when !module
> if (module) {
> unsigned int cpu = get_cpu();
> if (likely(module_is_live(module)))
> local_inc(&module->ref[cpu].count);
> else
> ret = 0; <--- error case
> put_cpu();
> }
> return ret; <----
> }
> ----
>
> What I understand about the code flow is:
> -- module live would return the flag stating that this module can be reference
> and is NOT being removed currently.
>
> 1. In case the module pointer passed is invalid (NULL) this function would
> return 1 (error case)
> 2. In case the module pointer is OK, and module is currently not being removed,
> reference count would be incremented and 1 returned (non error case)
> 3. In case the module pointer is OK, and module reference count can NOT be
> increased, 0 would be returned (error case).
>
> As you can observe from above points, 0 and 1 are returned for error cases. I am
> a little confused and wondering if there is something which I am missing in this
> code??.
>
> Can anyone help me out with this? Any help would be highly appreciated.
Somewhere in module.h you have:
#ifdef MODULE
#define THIS_MODULE (&__this_module)
#else /* !MODULE */
#define THIS_MODULE ((struct module *)0)
#endif
So this just means, that THIS_MODULE is NULL for compiled in modules
and therefore try_module_get(NULL) succeeds. It's not an error case.
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