Re: timing of module MODULE_STATE_COMING notifier

From: Frank Ch. Eigler
Date: Mon Aug 31 2015 - 08:53:31 EST


Hi, Rusty -

Thanks for your response!

> [...]
> > That patch also moved the MODULE_STATE_COMING notifier call to
> > complete_formation(), which is relatively early to its former
> > do_init_module() call site. It now precedes the parse_args(),
> > mod_sysfs_setup(), and trace_module_load() steps.
>
> Yes, parse_args() can enter the module, so you really want it before
> then.

Understood. (Perhaps mod_sysfs_setup() could sneak in ahead.)


> > Was the latter part of the change intended & necessary? It is
> > negatively impacting systemtap, which was relying on
> > MODULE_STATE_COMING being called from a fairly complete module
> > state - just before the actual initializer function call.

> Notifiers suck for stuff like this :( Module state has many steps,
> so my preference has been to open-code explicit hooks. [...]

You mean something like the trace_module_load()? (We will probably
experiment with hooking into that tracepoint instead of the notifier.)
A more hard-coded one with an in-kernel callee probably wouldn't help
module-resident clients like us.


- FChE
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