sched/hotplug: Convert cpu_[in]active notifiers to state machine

Now that we reduced everything into single notifiers, it's simple to move them
into the hotplug state machine space.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: rt@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index 1701705..b22b000 100644 (file)
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -59,18 +59,6 @@ struct notifier_block;
  * CPU notifier priorities.
  */
 enum {
-       /*
-        * SCHED_ACTIVE marks a cpu which is coming up active during
-        * CPU_ONLINE and CPU_DOWN_FAILED and must be the first notifier.  Is
-        * also cpuset according to cpu_active mask right after activating the
-        * cpu. During CPU_DOWN_PREPARE, SCHED_INACTIVE reversed the operation.
-        *
-        * This ordering guarantees consistent cpu_active mask and
-        * migration behavior to all cpu notifiers.
-        */
-       CPU_PRI_SCHED_ACTIVE    = INT_MAX,
-       CPU_PRI_SCHED_INACTIVE  = INT_MIN,
-
        /* migration should happen before other stuff but after perf */
        CPU_PRI_PERF            = 20,
        CPU_PRI_MIGRATION       = 10,

diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 99fd1d2..9e07468 100644 (file)
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -13,6 +13,7 @@ enum cpuhp_state {
        CPUHP_AP_ONLINE,
        CPUHP_TEARDOWN_CPU,
        CPUHP_AP_ONLINE_IDLE,
+       CPUHP_AP_ACTIVE,
        CPUHP_AP_SMPBOOT_THREADS,
        CPUHP_AP_NOTIFY_ONLINE,
        CPUHP_AP_ONLINE_DYN,

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 39597d0..1e5f961 100644 (file)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -373,6 +373,8 @@ extern void trap_init(void);
 extern void update_process_times(int user);
 extern void scheduler_tick(void);
 extern int sched_cpu_starting(unsigned int cpu);
+extern int sched_cpu_activate(unsigned int cpu);
+extern int sched_cpu_deactivate(unsigned int cpu);
 
 extern void sched_show_task(struct task_struct *p);
 

diff --git a/kernel/cpu.c b/kernel/cpu.c
index f46d02b..15402b7 100644 (file)
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -923,8 +923,6 @@ void cpuhp_online_idle(enum cpuhp_state state)
 
        st->state = CPUHP_AP_ONLINE_IDLE;
 
-       /* The cpu is marked online, set it active now */
-       set_cpu_active(cpu, true);
        /* Unpark the stopper thread and the hotplug thread of this cpu */
        stop_machine_unpark(cpu);
        kthread_unpark(st->thread);
@@ -1259,6 +1257,12 @@ static struct cpuhp_step cpuhp_ap_states[] = {
        [CPUHP_AP_ONLINE] = {
                .name                   = "ap:online",
        },
+       /* First state is scheduler control. Interrupts are enabled */
+       [CPUHP_AP_ACTIVE] = {
+               .name                   = "sched:active",
+               .startup                = sched_cpu_activate,
+               .teardown               = sched_cpu_deactivate,
+       },
        /* Handle smpboot threads park/unpark */
        [CPUHP_AP_SMPBOOT_THREADS] = {
                .name                   = "smpboot:threads",

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 541f9ab..73bcd93 100644 (file)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6634,9 +6634,6 @@ static void sched_domains_numa_masks_set(unsigned int cpu)
        int node = cpu_to_node(cpu);
        int i, j;
 
-       if (!sched_smp_initialized)
-               return;
-
        for (i = 0; i < sched_domains_numa_levels; i++) {
                for (j = 0; j < nr_node_ids; j++) {
                        if (node_distance(j, node) <= sched_domains_numa_distance[i])
@@ -6649,9 +6646,6 @@ static void sched_domains_numa_masks_clear(unsigned int cpu)
 {
        int i, j;
 
-       if (!sched_smp_initialized)
-               return;
-
        for (i = 0; i < sched_domains_numa_levels; i++) {
                for (j = 0; j < nr_node_ids; j++)
                        cpumask_clear_cpu(cpu, sched_domains_numa_masks[i][j]);
@@ -7051,12 +7045,9 @@ static int num_cpus_frozen;      /* used to mark begin/end of suspend/resume */
  * If we come here as part of a suspend/resume, don't touch cpusets because we
  * want to restore it back to its original state upon resume anyway.
  */
-static void cpuset_cpu_active(bool frozen)
+static void cpuset_cpu_active(void)
 {
-       if (!sched_smp_initialized)
-               return;
-
-       if (frozen) {
+       if (cpuhp_tasks_frozen) {
                /*
                 * num_cpus_frozen tracks how many CPUs are involved in suspend
                 * resume sequence. As long as this is not the last online
@@ -7077,17 +7068,14 @@ static void cpuset_cpu_active(bool frozen)
        cpuset_update_active_cpus(true);
 }
 
-static int cpuset_cpu_inactive(unsigned int cpu, bool frozen)
+static int cpuset_cpu_inactive(unsigned int cpu)
 {
        unsigned long flags;
        struct dl_bw *dl_b;
        bool overflow;
        int cpus;
 
-       if (!sched_smp_initialized)
-               return 0;
-
-       if (!frozen) {
+       if (!cpuhp_tasks_frozen) {
                rcu_read_lock_sched();
                dl_b = dl_bw_of(cpu);
 
@@ -7108,42 +7096,33 @@ static int cpuset_cpu_inactive(unsigned int cpu, bool frozen)
        return 0;
 }
 
-static int sched_cpu_active(struct notifier_block *nfb, unsigned long action,
-                           void *hcpu)
+int sched_cpu_activate(unsigned int cpu)
 {
-       unsigned int cpu = (unsigned long)hcpu;
+       set_cpu_active(cpu, true);
 
-       switch (action & ~CPU_TASKS_FROZEN) {
-       case CPU_DOWN_FAILED:
-       case CPU_ONLINE:
-               set_cpu_active(cpu, true);
+       if (sched_smp_initialized) {
                sched_domains_numa_masks_set(cpu);
-               cpuset_cpu_active(action & CPU_TASKS_FROZEN);
-               return NOTIFY_OK;
-       default:
-               return NOTIFY_DONE;
+               cpuset_cpu_active();
        }
+       return 0;
 }
 
-static int sched_cpu_inactive(struct notifier_block *nfb,
-                                       unsigned long action, void *hcpu)
+int sched_cpu_deactivate(unsigned int cpu)
 {
-       unsigned int cpu = (unsigned long)hcpu;
        int ret;
 
-       switch (action & ~CPU_TASKS_FROZEN) {
-       case CPU_DOWN_PREPARE:
-               set_cpu_active(cpu, false);
-               ret = cpuset_cpu_inactive(cpu, action & CPU_TASKS_FROZEN);
-               if (ret) {
-                       set_cpu_active(cpu, true);
-                       return notifier_from_errno(ret);
-               }
-               sched_domains_numa_masks_clear(cpu);
-               return NOTIFY_OK;
-       default:
-               return NOTIFY_DONE;
+       set_cpu_active(cpu, false);
+
+       if (!sched_smp_initialized)
+               return 0;
+
+       ret = cpuset_cpu_inactive(cpu);
+       if (ret) {
+               set_cpu_active(cpu, true);
+               return ret;
        }
+       sched_domains_numa_masks_clear(cpu);
+       return 0;
 }
 
 int sched_cpu_starting(unsigned int cpu)
@@ -7197,10 +7176,6 @@ static int __init migration_init(void)
        migration_call(&migration_notifier, CPU_ONLINE, cpu);
        register_cpu_notifier(&migration_notifier);
 
-       /* Register cpu active notifiers */
-       cpu_notifier(sched_cpu_active, CPU_PRI_SCHED_ACTIVE);
-       cpu_notifier(sched_cpu_inactive, CPU_PRI_SCHED_INACTIVE);
-
        return 0;
 }
 early_initcall(migration_init);