linux-kernel - Re: [PATCH] mm/page_alloc.c: Clean code by removing unnecessary initialization

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Date:   Fri, 4 Sep 2020 11:12:47 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     mateusznosek0@...il.com
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm/page_alloc.c: Clean code by removing unnecessary
 initialization

On Fri,  4 Sep 2020 15:24:22 +0200 mateusznosek0@...il.com wrote:

> From: Mateusz Nosek <mateusznosek0@...il.com>
> 
> Previously variable 'tmp' was initialized, but was not read later
> before reassigning. So the initialization can be removed.
> 
> ...
>
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -5637,7 +5637,7 @@ static int find_next_best_node(int node, nodemask_t *used_node_mask)
>  	int n, val;
>  	int min_val = INT_MAX;
>  	int best_node = NUMA_NO_NODE;
> -	const struct cpumask *tmp = cpumask_of_node(0);
> +	const struct cpumask *tmp;
>  
>  	/* Use the local node if we haven't already */
>  	if (!node_isset(node, *used_node_mask)) {

OK.   But we may as well kill tmp altogether?

--- a/mm/page_alloc.c~mm-page_allocc-clean-code-by-removing-unnecessary-initialization-fix
+++ a/mm/page_alloc.c
@@ -5637,7 +5637,6 @@ static int find_next_best_node(int node,
 	int n, val;
 	int min_val = INT_MAX;
 	int best_node = NUMA_NO_NODE;
-	const struct cpumask *tmp;
 
 	/* Use the local node if we haven't already */
 	if (!node_isset(node, *used_node_mask)) {
@@ -5658,8 +5657,7 @@ static int find_next_best_node(int node,
 		val += (n < node);
 
 		/* Give preference to headless and unused nodes */
-		tmp = cpumask_of_node(n);
-		if (!cpumask_empty(tmp))
+		if (!cpumask_empty(cpumask_of_node(n)))
 			val += PENALTY_FOR_NODE_WITH_CPUS;
 
 		/* Slight preference for less loaded node */
_