linux-kernel - [PATCH] sched/topology: Remove redundant variable and fix incorrect type in build_sched

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Date:   Fri, 18 Feb 2022 21:57:43 +0530
From:   K Prateek Nayak <kprateek.nayak@....com>
To:     <peterz@...radead.org>
CC:     <aubrey.li@...ux.intel.com>, <efault@....de>,
        <gautham.shenoy@....com>, <linux-kernel@...r.kernel.org>,
        <mgorman@...hsingularity.net>, <mingo@...nel.org>,
        <song.bao.hua@...ilicon.com>, <srikar@...ux.vnet.ibm.com>,
        <valentin.schneider@....com>, <vincent.guittot@...aro.org>
Subject: [PATCH] sched/topology: Remove redundant variable and fix incorrect type in build_sched_domains

While investigating the sparse warning reported by the LKP bot [1],
observed that we have a redundant variable "top" in the function
build_sched_domains that was introduced in the recent commit
e496132ebedd ("sched/fair: Adjust the allowed NUMA imbalance when
SD_NUMA spans multiple LLCs")

The existing variable "sd" suffices which allows us to remove the
redundant variable "top" while annotating the other variable "top_p"
with the "__rcu" annotation to silence the sparse warning.

[1] https://lore.kernel.org/lkml/202202170853.9vofgC3O-lkp@intel.com/

Fixes: e496132ebedd ("sched/fair: Adjust the allowed NUMA imbalance when SD_NUMA spans multiple LLCs")
Reported-by: kernel test robot <lkp@...el.com>
Signed-off-by: K Prateek Nayak <kprateek.nayak@....com>
---
 kernel/sched/topology.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index e6cd55951304..4b757fb8f661 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -2255,7 +2255,7 @@ build_sched_domains(const struct cpumask *cpu_map, struct sched_domain_attr *att
 
 			if (!(sd->flags & SD_SHARE_PKG_RESOURCES) && child &&
 			    (child->flags & SD_SHARE_PKG_RESOURCES)) {
-				struct sched_domain *top, *top_p;
+				struct sched_domain __rcu *top_p;
 				unsigned int nr_llcs;
 
 				/*
@@ -2280,11 +2280,9 @@ build_sched_domains(const struct cpumask *cpu_map, struct sched_domain_attr *att
 				sd->imb_numa_nr = imb;
 
 				/* Set span based on the first NUMA domain. */
-				top = sd;
-				top_p = top->parent;
+				top_p = sd->parent;
 				while (top_p && !(top_p->flags & SD_NUMA)) {
-					top = top->parent;
-					top_p = top->parent;
+					top_p = top_p->parent;
 				}
 				imb_span = top_p ? top_p->span_weight : sd->span_weight;
 			} else {
-- 
2.25.1