Re: [PATCH v4 3/4] ftrace/module: remove ftrace module notifier

[Miroslav Benes]

On Mon, 8 Feb 2016, Jessica Yu wrote:

> Remove the ftrace module notifier in favor of directly calling
> ftrace_module_enable() and ftrace_release_mod() in the module loader.
> Hard-coding the function calls directly in the module loader removes
> dependence on the module notifier call chain and provides better
> visibility and control over what gets called when, which is important
> to kernel utilities such as livepatch.
> 
> This fixes a notifier ordering issue in which the ftrace module notifier
> (and hence ftrace_module_enable()) for coming modules was being called
> after klp_module_notify(), which caused livepatch modules to initialize
> incorrectly. This patch removes dependence on the module notifier call
> chain in favor of hard coding the corresponding function calls in the
> module loader. This ensures that ftrace and livepatch code get called in
> the correct order on patch module load and unload.
> 
> Fixes: 5156dca34a3e ("ftrace: Fix the race between ftrace and insmod")
> Signed-off-by: Jessica Yu <jeyu@xxxxxxxxxx>
> Reviewed-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
> Reviewed-by: Petr Mladek <pmladek@xxxxxxx>
> Acked-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>

Reviewed-by: Miroslav Benes <mbenes@xxxxxxx>

Miroslav