From: Frederic Weisbecker <frederic@kernel.org>
Date: Mon, 7 Feb 2022 15:59:07 +0000 (+0100)
Subject: sched/isolation: Consolidate check for housekeeping minimum service
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=6367b600e31c6b211eadee7bf7f4ed8c755e9176;p=linux.git

sched/isolation: Consolidate check for housekeeping minimum service

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>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juri Lelli <juri.lelli@redhat.com>
Reviewed-by: Phil Auld <pauld@redhat.com>
Link: https://lore.kernel.org/r/20220207155910.527133-6-frederic@kernel.org
---

diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
index a735d9e229dde..23085e665faac 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)) {