On 08/02/17 12:13, Andriy Gapon wrote:

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:

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

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!

The same applies to:


Not sure if this answers your question.

If a SYSCTL() is TUNABLE, it's procedure can be called when the sysctl is created. Else the SYSCTL() procedure callback might be called right after it's registered. I think there is an own subsystem in sys/kernel.h which takes care of the actual SYSCTL() creation/destruction - after the linker is involved.

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