Re: [PATCH v2 1/2] livepatch: Initialize shadow variables safely by a custom callback
From: Josh Poimboeuf
Date: Fri Apr 06 2018 - 18:36:19 EST
On Thu, Apr 05, 2018 at 02:23:14PM +0200, Petr Mladek wrote:
> @@ -150,6 +149,23 @@ static void *__klp_shadow_get_or_alloc(void *obj, unsigned long id, void *data,
> goto exists;
> }
>
> + new_shadow->obj = obj;
> + new_shadow->id = id;
> +
> + if (ctor) {
> + int err;
> +
> + err = ctor(obj, new_shadow->data, ctor_data);
> + if (err) {
> + spin_unlock_irqrestore(&klp_shadow_lock, flags);
> + kfree(new_shadow);
> + WARN(1,
> + "Failed to construct shadow variable <%p, %lx>\n",
> + obj, id);
> + return NULL;
> + }
> + }
> +
I'm not sure why a constructor would return an error, though I guess it
doesn't hurt to allow it.
The WARN seems excessive though, IMO. The constructor itself can warn
(or printk or whatever else) if it thinks its warranted.
Also I think the 'err' variable isn't really needed.
--
Josh