Re: [PATCH] libkmod-module: Remove directory existence check for KMOD_MODULE_BUILTIN

From: Rusty Russell
Date: Wed Feb 18 2015 - 19:57:56 EST

Lucas De Marchi <> writes:
> On Wed, Feb 18, 2015 at 2:07 AM, Rusty Russell <rusty@xxxxxxxxxxxxxxx> wrote:
> Yeah, I just thought (an wanted that) the attributes were being
> created first and then hooked up in the sysfs tree under
> /sys/module/<modulename>. I.e. if the directory exists and there's no
> initstate this is because it's a builtin module. I don't want to
> wait/sleep on the file to appear because users of
> kmod_module_get_initstate() may not tolerate this behavior.
> Looking up at the old module-init-tools, it used an ugly loop with
> usleep() before trying to read the file again :-/
> Can we change kernel side guaranteeing the initstate file appears
> together with the directory?

Greg? The core problem is that kmod looks for
/sys/module/<name>/initstate; if it's not there, it assumes a builtin

However, this is racy when a module is being inserted. Is there a way
to create this sysfs file and dir atomically?

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