[PATCH 3/3] lib/group_cpus.c: honor housekeeping config when grouping CPUs

[Daniel Wagner <dwagner@xxxxxxx>]

group_cpus_evenly distributes all present CPUs into groups. This
ignores the isolcpus configuration and assigns isolated CPUs into the
groups.

Make group_cpus_evenly aware of isolcpus configuration and use the
housekeeping CPU mask as base for distributing the available CPUs into
groups.

Signed-off-by: Daniel Wagner <dwagner@xxxxxxx>
---
 lib/group_cpus.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 62 insertions(+), 2 deletions(-)

diff --git a/lib/group_cpus.c b/lib/group_cpus.c
index ee272c4cefcc..f1517a44abc9 100644
--- a/lib/group_cpus.c
+++ b/lib/group_cpus.c
@@ -8,6 +8,7 @@
 #include <linux/cpu.h>
 #include <linux/sort.h>
 #include <linux/group_cpus.h>
+#include <linux/sched/isolation.h>
 
 #ifdef CONFIG_SMP
 
@@ -330,7 +331,7 @@ static int __group_cpus_evenly(unsigned int startgrp, unsigned int numgrps,
 }
 
 /**
- * group_cpus_evenly - Group all CPUs evenly per NUMA/CPU locality
+ * group_possible_cpus_evenly - Group all CPUs evenly per NUMA/CPU locality
  * @numgrps: number of groups
  *
  * Return: cpumask array if successful, NULL otherwise. And each element
@@ -344,7 +345,7 @@ static int __group_cpus_evenly(unsigned int startgrp, unsigned int numgrps,
  * We guarantee in the resulted grouping that all CPUs are covered, and
  * no same CPU is assigned to multiple groups
  */
-struct cpumask *group_cpus_evenly(unsigned int numgrps)
+static struct cpumask *group_possible_cpus_evenly(unsigned int numgrps)
 {
 	unsigned int curgrp = 0, nr_present = 0, nr_others = 0;
 	cpumask_var_t *node_to_cpumask;
@@ -423,6 +424,65 @@ struct cpumask *group_cpus_evenly(unsigned int numgrps)
 	}
 	return masks;
 }
+
+static struct cpumask *group_mask_cpus_evenly(unsigned int numgrps,
+					      const struct cpumask *cpu_mask)
+{
+	cpumask_var_t *node_to_cpumask;
+	cpumask_var_t nmsk;
+	int ret = -ENOMEM;
+	struct cpumask *masks = NULL;
+
+	if (!zalloc_cpumask_var(&nmsk, GFP_KERNEL))
+		return NULL;
+
+	node_to_cpumask = alloc_node_to_cpumask();
+	if (!node_to_cpumask)
+		goto fail_nmsk;
+
+	masks = kcalloc(numgrps, sizeof(*masks), GFP_KERNEL);
+	if (!masks)
+		goto fail_node_to_cpumask;
+
+	build_node_to_cpumask(node_to_cpumask);
+
+	ret = __group_cpus_evenly(0, numgrps, node_to_cpumask, cpu_mask, nmsk,
+				  masks);
+
+fail_node_to_cpumask:
+	free_node_to_cpumask(node_to_cpumask);
+
+fail_nmsk:
+	free_cpumask_var(nmsk);
+	if (ret < 0) {
+		kfree(masks);
+		return NULL;
+	}
+	return masks;
+}
+
+/**
+ * group_cpus_evenly - Group all CPUs evenly per NUMA/CPU locality
+ * @numgrps: number of groups
+ *
+ * Return: cpumask array if successful, NULL otherwise. And each element
+ * includes CPUs assigned to this group
+ *
+ * @group_possible_cpus_evently is used for distributing the cpus
+ * on all possible cpus in absence of isolcpus command line argument.
+ * If the isolcpus argument is used with io_queue option only
+ * the housekeeping CPUs are considered.
+ */
+struct cpumask *group_cpus_evenly(unsigned int numgrps)
+{
+	const struct cpumask *io_queue_mask;
+
+	io_queue_mask = housekeeping_cpumask(HK_TYPE_IO_QUEUE);
+	if (!cpumask_empty(io_queue_mask))
+		return group_mask_cpus_evenly(numgrps, io_queue_mask);
+	else
+		return group_possible_cpus_evenly(numgrps);
+}
 #else /* CONFIG_SMP */
 struct cpumask *group_cpus_evenly(unsigned int numgrps)
 {

-- 
2.45.2