From: Rusty Russell <rusty@rustcorp.com.au>
To: "Frank Ch. Eigler" <fche@redhat.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: timing of module MODULE_STATE_COMING notifier
In-Reply-To: <20150831000642.GG29756@redhat.com>
References: <20150831000642.GG29756@redhat.com>
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Date: Mon, 31 Aug 2015 11:06:22 +0930
Message-ID: <87si70p7c9.fsf@rustcorp.com.au>
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"Frank Ch. Eigler" <fche@redhat.com> writes:
> Hi, Rusty -
>
> We just [1] came across your patch [2] from last year (merged into
> 3.17), wherein the RO/NX mapping settings for module sections were
> moved to an earlier point in the module-loading sequence.
>
> 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.

> 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.  This would seem to reinforce that preference...

Thanks,
Rusty.
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