linux-kernel - Re: [PATCH 6/8] livepatch: Remove Nop structures when unused

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Date:   Fri, 6 Apr 2018 17:07:23 -0500
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     Petr Mladek <pmladek@...e.com>
Cc:     Jiri Kosina <jikos@...nel.org>, Miroslav Benes <mbenes@...e.cz>,
        Jason Baron <jbaron@...mai.com>,
        Joe Lawrence <joe.lawrence@...hat.com>,
        Jessica Yu <jeyu@...nel.org>,
        Evgenii Shatokhin <eshatokhin@...tuozzo.com>,
        live-patching@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 6/8] livepatch: Remove Nop structures when unused

On Fri, Mar 23, 2018 at 01:00:26PM +0100, Petr Mladek wrote:
> Replaced patches are removed from the stack when the transition is
> finished. It means that Nop structures will never be needed again
> and can be removed. Why should we care?

Warning, grammar pedantry ahead.

"Nop" isn't a proper noun, so it shouldn't be capitalized (here and in
the patch subject).

Also, "NOP", used elsewhere, might be confused with x86 NOP
instructions.  I would vote for "nop" everywhere.

> @@ -146,6 +155,21 @@ static void klp_complete_transition(void)
>  	if (!klp_forced && klp_target_state == KLP_UNPATCHED)
>  		module_put(klp_transition_patch->mod);
>  
> +	if (klp_transition_patch->replace && klp_target_state == KLP_PATCHED) {
> +		/*
> +		 * We do not need to wait until the objects are really freed.
> +		 * We will never need them again because the patch must be on
> +		 * the bottom of the stack now.
> +		 */
> +		klp_free_objects_dynamic(klp_transition_patch);
> +		/*
> +		 * Replace behavior will not longer be needed. Avoid the related
> +		 * code when disabling and enabling again.

"not longer" -> "no longer"

-- 
Josh