Date: Wed, 2 Aug 2017 13:13:11 +0300 From: Andriy Gapon <avg@FreeBSD.org> To: FreeBSD Hackers <freebsd-hackers@FreeBSD.org>, FreeBSD Current <freebsd-current@FreeBSD.org> Subject: order of executing MOD_LOAD and registering module sysctl-s Message-ID: <62e7ab4d-8956-545e-b204-4fb63cfe5fbf@FreeBSD.org>
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As far as I understand a module initialization routine is executed via the
sysinit mechanism. Specifically, module_register_init is set up as the sysinit
function for every module and it calls MOD_EVENT(mod, MOD_LOAD) to invoke the
module event handler.
In linker_load_file() I see the following code:
linker_file_register_sysctls(lf);
linker_file_sysinit(lf);
I think that this means that any statically declared sysctl-s in the module
would be registered before the module receives the MOD_LOAD event.
It's possible that some of the sysctl-s could have procedures as handlers and
they might access data that is supposed to be initialized by the module event
handler.
So, for example, running sysctl -a at just the right moment during the loading
of a module might end up in an expected behavior (including a crash).
Is my interpretation of how the code works correct?
Can the order of linker_file_sysinit and linker_file_register_sysctls be changed
without a great risk?
Thank you!
P.S.
The same applies to:
linker_file_sysuninit(file);
linker_file_unregister_sysctls(file);
--
Andriy Gapon
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