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Subject[PATCH V3 18/39] x86/intel_rdt: Add utility to test if tasks assigned to resource group
Date
In considering changes to a resource group it becomes necessary to know
whether tasks have been assigned to the resource group in question.

Introduce a new utility that can be used to check if any tasks have been
assigned to a particular resource group.

Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
---
arch/x86/kernel/cpu/intel_rdt.h | 1 +
arch/x86/kernel/cpu/intel_rdt_rdtgroup.c | 26 ++++++++++++++++++++++++++
2 files changed, 27 insertions(+)

diff --git a/arch/x86/kernel/cpu/intel_rdt.h b/arch/x86/kernel/cpu/intel_rdt.h
index fa2aa7e8ad73..e33b1215f394 100644
--- a/arch/x86/kernel/cpu/intel_rdt.h
+++ b/arch/x86/kernel/cpu/intel_rdt.h
@@ -465,6 +465,7 @@ int rdtgroup_cbm_overlaps(struct rdt_resource *r, struct rdt_domain *d,
unsigned int rdtgroup_cbm_to_size(struct rdt_resource *r, struct rdt_domain *d,
u32 cbm);
enum rdtgrp_mode rdtgroup_mode_by_closid(int closid);
+int rdtgroup_tasks_assigned(struct rdtgroup *r);
struct rdt_domain *get_domain_from_cpu(int cpu, struct rdt_resource *r);
int update_domains(struct rdt_resource *r, int closid);
void closid_free(int closid);
diff --git a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
index 541103a2dea0..f2da6a2827c8 100644
--- a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
+++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
@@ -564,6 +564,32 @@ static int __rdtgroup_move_task(struct task_struct *tsk,
return ret;
}

+/**
+ * rdtgroup_tasks_assigned - Test if tasks have been assigned to resource group
+ * @r: Resource group
+ *
+ * Return: 1 if tasks have been assigned to @r, 0 otherwise
+ */
+int rdtgroup_tasks_assigned(struct rdtgroup *r)
+{
+ struct task_struct *p, *t;
+ int ret = 0;
+
+ lockdep_assert_held(&rdtgroup_mutex);
+
+ rcu_read_lock();
+ for_each_process_thread(p, t) {
+ if ((r->type == RDTCTRL_GROUP && t->closid == r->closid) ||
+ (r->type == RDTMON_GROUP && t->rmid == r->mon.rmid)) {
+ ret = 1;
+ break;
+ }
+ }
+ rcu_read_unlock();
+
+ return ret;
+}
+
static int rdtgroup_task_write_permission(struct task_struct *task,
struct kernfs_open_file *of)
{
--
2.13.6
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