[PATCH v4 2/8] sched: Move is_cpu_allowed() into sched.h

From: David Vernet
Date: Mon Dec 11 2023 - 19:32:05 EST


is_cpu_allowed() exists as a static inline function in core.c. The
functionality offered by is_cpu_allowed() is useful to scheduling
policies as well, e.g. to determine whether a runnable task can be
migrated to another core that would otherwise go idle.

Let's move it to sched.h.

Signed-off-by: David Vernet <void@xxxxxxxxxxxxx>
---
kernel/sched/core.c | 31 -------------------------------
kernel/sched/sched.h | 31 +++++++++++++++++++++++++++++++
2 files changed, 31 insertions(+), 31 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index fb6f505d5792..9ad7f0255e14 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -48,7 +48,6 @@
#include <linux/kcov.h>
#include <linux/kprobes.h>
#include <linux/llist_api.h>
-#include <linux/mmu_context.h>
#include <linux/mmzone.h>
#include <linux/mutex_api.h>
#include <linux/nmi.h>
@@ -2469,36 +2468,6 @@ static inline bool rq_has_pinned_tasks(struct rq *rq)
return rq->nr_pinned;
}

-/*
- * Per-CPU kthreads are allowed to run on !active && online CPUs, see
- * __set_cpus_allowed_ptr() and select_fallback_rq().
- */
-static inline bool is_cpu_allowed(struct task_struct *p, int cpu)
-{
- /* When not in the task's cpumask, no point in looking further. */
- if (!cpumask_test_cpu(cpu, p->cpus_ptr))
- return false;
-
- /* migrate_disabled() must be allowed to finish. */
- if (is_migration_disabled(p))
- return cpu_online(cpu);
-
- /* Non kernel threads are not allowed during either online or offline. */
- if (!(p->flags & PF_KTHREAD))
- return cpu_active(cpu) && task_cpu_possible(cpu, p);
-
- /* KTHREAD_IS_PER_CPU is always allowed. */
- if (kthread_is_per_cpu(p))
- return cpu_online(cpu);
-
- /* Regular kernel threads don't get to stay during offline. */
- if (cpu_dying(cpu))
- return false;
-
- /* But are allowed during online. */
- return cpu_online(cpu);
-}
-
/*
* This is how migration works:
*
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 5afdbd7e2381..53fe2294eec7 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -44,6 +44,7 @@
#include <linux/lockdep.h>
#include <linux/minmax.h>
#include <linux/mm.h>
+#include <linux/mmu_context.h>
#include <linux/module.h>
#include <linux/mutex_api.h>
#include <linux/plist.h>
@@ -1206,6 +1207,36 @@ static inline bool is_migration_disabled(struct task_struct *p)
#endif
}

+/*
+ * Per-CPU kthreads are allowed to run on !active && online CPUs, see
+ * __set_cpus_allowed_ptr() and select_fallback_rq().
+ */
+static inline bool is_cpu_allowed(struct task_struct *p, int cpu)
+{
+ /* When not in the task's cpumask, no point in looking further. */
+ if (!cpumask_test_cpu(cpu, p->cpus_ptr))
+ return false;
+
+ /* migrate_disabled() must be allowed to finish. */
+ if (is_migration_disabled(p))
+ return cpu_online(cpu);
+
+ /* Non kernel threads are not allowed during either online or offline. */
+ if (!(p->flags & PF_KTHREAD))
+ return cpu_active(cpu) && task_cpu_possible(cpu, p);
+
+ /* KTHREAD_IS_PER_CPU is always allowed. */
+ if (kthread_is_per_cpu(p))
+ return cpu_online(cpu);
+
+ /* Regular kernel threads don't get to stay during offline. */
+ if (cpu_dying(cpu))
+ return false;
+
+ /* But are allowed during online. */
+ return cpu_online(cpu);
+}
+
DECLARE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);

#define cpu_rq(cpu) (&per_cpu(runqueues, (cpu)))
--
2.42.1