On Tue, 11 Apr 2017, Petr Mladek wrote:
> klp_init_transition() does not set func->transition for immediate patches.
> Then klp_ftrace_handler() could use the new code immediately. As a result,
> it is not safe to put the livepatch module in klp_cancel_transition().
>
> This patch reverts most of the last minute changes klp_cancel_transition().
> It keeps the warning about a misuse because it still makes sense.
>
> Signed-off-by: Petr Mladek <pmla...@suse.com>
> ---
> Hi,
>
> I am afraid that Mirek was not right in the mail
> https://lkml.kernel.org/r/alpine.lsu.2.20.1702161504020.16...@pobox.suse.cz
> IMHO, it is not safe to put the module when the immediate
> patch cannot be applied.
>
> Best Regards,
> Petr
You're right, Petr. Thanks for fixing my fault.
If needed, we could still follow the idea - set func->transition even for
immediate patches/funcs. But for now, removing the code is the best.
Acked-by: Miroslav Benes <mbe...@suse.cz>
Jiri, this (obviously) needs to go to 4.12 with the patch set...
Miroslav
> kernel/livepatch/transition.c | 20 --------------------
> 1 file changed, 20 deletions(-)
>
> diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c
> index 2de09e0c4e5c..adc0cc64aa4b 100644
> --- a/kernel/livepatch/transition.c
> +++ b/kernel/livepatch/transition.c
> @@ -120,31 +120,11 @@ static void klp_complete_transition(void)
> */
> void klp_cancel_transition(void)
> {
> - struct klp_patch *patch = klp_transition_patch;
> - struct klp_object *obj;
> - struct klp_func *func;
> - bool immediate_func = false;
> -
> if (WARN_ON_ONCE(klp_target_state != KLP_PATCHED))
> return;
>
> klp_target_state = KLP_UNPATCHED;
> klp_complete_transition();
> -
> - /*
> - * In the enable error path, even immediate patches can be safely
> - * removed because the transition hasn't been started yet.
> - *
> - * klp_complete_transition() doesn't have a module_put() for immediate
> - * patches, so do it here.
> - */
> - klp_for_each_object(patch, obj)
> - klp_for_each_func(obj, func)
> - if (func->immediate)
> - immediate_func = true;
> -
> - if (patch->immediate || immediate_func)
> - module_put(patch->mod);
> }
>
> /*
> --
> 1.8.5.6
>
