From:   Frederic Weisbecker <frederic@kernel.org>
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     LKML <linux-kernel@vger.kernel.org>,
        Frederic Weisbecker <frederic@kernel.org>,
        Tejun Heo <tj@kernel.org>, Juri Lelli <juri.lelli@redhat.com>,
        Alex Belits <abelits@marvell.com>,
        Nitesh Lal <nilal@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Nicolas Saenz <nsaenzju@redhat.com>,
        Christoph Lameter <cl@gentwo.de>,
        Marcelo Tosatti <mtosatti@redhat.com>,
        Zefan Li <lizefan.x@bytedance.com>,
        Paul Gortmaker <paul.gortmaker@windriver.com>,
        "Paul E . McKenney" <paulmck@kernel.org>
Subject: [PATCH 5/8] sched/isolation: Consolidate check for housekeeping minimum service
Date:   Tue,  4 Jan 2022 15:49:41 +0100
Message-Id: <20220104144944.1278663-6-frederic@kernel.org>
In-Reply-To: <20220104144944.1278663-1-frederic@kernel.org>
References: <20220104144944.1278663-1-frederic@kernel.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

There can be two subsequent calls to housekeeping_setup() due to
"nohz_full=" and "isolcpus=" that can mix up.  The two passes each have
their own way to deal with an empty housekeeping set of CPUs.
Consolidate this part and remove the awful "tmp" based naming.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Nitesh Lal <nilal@redhat.com>
Cc: Nicolas Saenz <nsaenzju@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Christoph Lameter <cl@gentwo.de>
Cc: Tejun Heo <tj@kernel.org>
Cc: Zefan Li <lizefan.x@bytedance.com>
Cc: Alex Belits <abelits@marvell.com>
---
 kernel/sched/isolation.c | 35 +++++++++++++++++------------------
 1 file changed, 17 insertions(+), 18 deletions(-)

diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
index a735d9e229dd..23085e665faa 100644
--- a/kernel/sched/isolation.c
+++ b/kernel/sched/isolation.c
@@ -91,8 +91,7 @@ void __init housekeeping_init(void)
 
 static int __init housekeeping_setup(char *str, enum hk_flags flags)
 {
-	cpumask_var_t non_housekeeping_mask;
-	cpumask_var_t tmp;
+	cpumask_var_t non_housekeeping_mask, housekeeping_staging;
 
 	alloc_bootmem_cpumask_var(&non_housekeeping_mask);
 	if (cpulist_parse(str, non_housekeeping_mask) < 0) {
@@ -101,32 +100,32 @@ static int __init housekeeping_setup(char *str, enum hk_flags flags)
 		return 0;
 	}
 
-	alloc_bootmem_cpumask_var(&tmp);
-	if (!housekeeping_flags) {
-		alloc_bootmem_cpumask_var(&housekeeping_mask);
-		cpumask_andnot(housekeeping_mask,
-			       cpu_possible_mask, non_housekeeping_mask);
+	alloc_bootmem_cpumask_var(&housekeeping_staging);
+	cpumask_andnot(housekeeping_staging,
+		       cpu_possible_mask, non_housekeeping_mask);
 
-		cpumask_andnot(tmp, cpu_present_mask, non_housekeeping_mask);
-		if (cpumask_empty(tmp)) {
+	if (!cpumask_intersects(cpu_present_mask, housekeeping_staging)) {
+		__cpumask_set_cpu(smp_processor_id(), housekeeping_staging);
+		__cpumask_clear_cpu(smp_processor_id(), non_housekeeping_mask);
+		if (!housekeeping_flags) {
 			pr_warn("Housekeeping: must include one present CPU, "
 				"using boot CPU:%d\n", smp_processor_id());
-			__cpumask_set_cpu(smp_processor_id(), housekeeping_mask);
-			__cpumask_clear_cpu(smp_processor_id(), non_housekeeping_mask);
 		}
+	}
+
+	if (!housekeeping_flags) {
+		alloc_bootmem_cpumask_var(&housekeeping_mask);
+		cpumask_copy(housekeeping_mask, housekeeping_staging);
 	} else {
-		cpumask_andnot(tmp, cpu_present_mask, non_housekeeping_mask);
-		if (cpumask_empty(tmp))
-			__cpumask_clear_cpu(smp_processor_id(), non_housekeeping_mask);
-		cpumask_andnot(tmp, cpu_possible_mask, non_housekeeping_mask);
-		if (!cpumask_equal(tmp, housekeeping_mask)) {
+		if (!cpumask_equal(housekeeping_staging, housekeeping_mask)) {
 			pr_warn("Housekeeping: nohz_full= must match isolcpus=\n");
-			free_bootmem_cpumask_var(tmp);
+			free_bootmem_cpumask_var(housekeeping_staging);
 			free_bootmem_cpumask_var(non_housekeeping_mask);
 			return 0;
 		}
 	}
-	free_bootmem_cpumask_var(tmp);
+
+	free_bootmem_cpumask_var(housekeeping_staging);
 
 	if ((flags & HK_FLAG_TICK) && !(housekeeping_flags & HK_FLAG_TICK)) {
 		if (IS_ENABLED(CONFIG_NO_HZ_FULL)) {
-- 
2.25.1