linux-kernel - [PATCH] sched/isolcpus: Show isolated cpu map

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Message-ID: <1486979039-17874-1-git-send-email-wangkefeng.wang@huawei.com>
Date:   Mon, 13 Feb 2017 17:43:59 +0800
From:   Kefeng Wang <wangkefeng.wang@...wei.com>
To:     Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        <linux-kernel@...r.kernel.org>
CC:     <guohanjun@...wei.com>, Kefeng Wang <wangkefeng.wang@...wei.com>,
        "Prarit Bhargava" <prarit@...hat.com>
Subject: [PATCH] sched/isolcpus: Show isolated cpu map

The commit a6e4491c682a ("sched/isolcpus: Output warning when the
'isolcpus=' kernel parameter is invalid") adds an error message
when specified cpu bigger than nr_cpu_ids, but nr_cpumask_bits in
cpulist_parse() could be nr_cpu_ids or NR_CPUS.

eg, NR_CPUS=64, nr_cpu_ids=8 in ARM64, cpulist_parse() won't return
-ERANGE if isolcpus=1-10;

Let's show the isolated cpu map and drop the improper error message.

Cc: Prarit Bhargava <prarit@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Ingo Molnar <mingo@...nel.org>
Signed-off-by: Kefeng Wang <wangkefeng.wang@...wei.com>
---
 kernel/sched/core.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index c56fb57..13a122d 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6076,13 +6076,16 @@ static void update_top_cache_domain(int cpu)
 /* Setup the mask of cpus configured for isolated domains */
 static int __init isolated_cpu_setup(char *str)
 {
-	int ret;
+	int cpu;
 
 	alloc_bootmem_cpumask_var(&cpu_isolated_map);
-	ret = cpulist_parse(str, cpu_isolated_map);
-	if (ret) {
-		pr_err("sched: Error, all isolcpus= values must be between 0 and %d\n", nr_cpu_ids);
-		return 0;
+	cpulist_parse(str, cpu_isolated_map);
+
+	if (!cpumask_empty(cpu_isolated_map)) {
+		pr_cont("sched: isolated cpus [ ");
+		for_each_cpu(cpu, cpu_isolated_map)
+			pr_cont("%d ", cpu);
+		pr_cont("]\n");
 	}
 	return 1;
 }
-- 
1.7.12.4