linux-kernel - [PATCH v4 2/8] sched: Move is_cpu

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Date:   Mon, 11 Dec 2023 18:31:35 -0600
From:   David Vernet <void@...ifault.com>
To:     linux-kernel@...r.kernel.org
Cc:     mingo@...hat.com, peterz@...radead.org, juri.lelli@...hat.com,
        bsegall@...gle.com, mgorman@...e.de, bristot@...hat.com,
        vschneid@...hat.com, youssefesmat@...gle.com, joelaf@...gle.com,
        roman.gushchin@...ux.dev, yu.c.chen@...el.com,
        kprateek.nayak@....com, gautham.shenoy@....com,
        aboorvad@...ux.vnet.ibm.com, wuyun.abel@...edance.com,
        tj@...nel.org, kernel-team@...a.com
Subject: [PATCH v4 2/8] sched: Move is_cpu_allowed() into sched.h

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@...ifault.com>
---
 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