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SubjectRe: [PATCH V4 8/9] jump_label: Batch updates if arch supports it
On Mon,  4 Feb 2019 20:59:01 +0100
Daniel Bristot de Oliveira <bristot@redhat.com> wrote:

> --- a/kernel/jump_label.c
> +++ b/kernel/jump_label.c
> @@ -407,6 +407,7 @@ bool jump_label_can_update_check(struct jump_entry *entry, bool init)
> return 0;
> }
>
> +#ifndef HAVE_JUMP_LABEL_BATCH
> static void __jump_label_update(struct static_key *key,
> struct jump_entry *entry,
> struct jump_entry *stop,
> @@ -419,6 +420,34 @@ static void __jump_label_update(struct static_key *key,
> }
> }
> }
> +#else
> +static void __jump_label_update(struct static_key *key,
> + struct jump_entry *entry,
> + struct jump_entry *stop,
> + bool init)
> +{
> + for_each_label_entry(key, entry, stop) {
> +
> + if (!jump_label_can_update_check(entry, init))
> + continue;
> +
> + if (arch_jump_label_transform_queue(entry,
> + jump_label_type(entry)))
> + continue;
> +
> + /*
> + * Queue's overflow: Apply the current queue, and then
> + * queue again. If it stills not possible to queue, BUG!
> + */
> + arch_jump_label_transform_apply();
> + if (!arch_jump_label_transform_queue(entry,
> + jump_label_type(entry))) {
> + BUG();

Please do not relay on BUG(), since in both case (applied or not),
jump_label is not critical for normal operation. I think you should use
WARN_ONCE() here and lock the jump_label so that root user can report it
to us :)

Thank you,


--
Masami Hiramatsu <mhiramat@kernel.org>

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