clarifying the use of try_module_get()

[John S O'Sullivan]

Hi,

I have read the FAQ at
http://people.redhat.com/zaitcev/notes/rusty_mod_faq.news and looked at a
lot of drivers in the kernel but I am still confused about the use of
try_module_get() and exported symbols.

As I understand it try_module_get() should be used in place of the
depreciated MOD_COUNTS so if I have a module moduleA. I use
try_module_get(THIS_MODULE) in the open function and module_put(THIS_MODULE)
in the release funtion.

What do I need to do in the following scenario:

moduleA has a function foo() which I export with EXPORT_SYMBOL(foo). I now
want to call that function foo() from a second module moduleB.

Do I have to wrap the call with try_module_get(moduleA) for example

moduleB_calling_foo_in_moduleA
{
if (try_module_get(moduleA))
foo();

}

If so how do I get a reference to moduleA from within moduleB?




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[Arjan van de Ven]

Post by John S O'Sullivan
As I understand it try_module_get() should be used in place of the
depreciated MOD_COUNTS so if I have a module moduleA. I use
try_module_get(THIS_MODULE) in the open function and module_put(THIS_MODULE)
in the release funtion.

not really; you're supposed to have a .owner set, so that the middle
layers can keep that counts for you.




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Archive: http://mail.nl.linux.org/kernelnewbies/
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