sched: Consolidate the notifier maze

We can maintain the ordering of the scheduler cpu hotplug functionality nicely
in one notifer. Get rid of the maze.

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 f9b1fab..1701705 100644 (file)
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -61,19 +61,15 @@ struct notifier_block;
 enum {
        /*
         * SCHED_ACTIVE marks a cpu which is coming up active during
-        * CPU_ONLINE and CPU_DOWN_FAILED and must be the first
-        * notifier.  CPUSET_ACTIVE adjusts cpuset according to
-        * cpu_active mask right after SCHED_ACTIVE.  During
-        * CPU_DOWN_PREPARE, SCHED_INACTIVE and CPUSET_INACTIVE are
-        * ordered in the similar way.
+        * 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_CPUSET_ACTIVE   = INT_MAX - 1,
-       CPU_PRI_SCHED_INACTIVE  = INT_MIN + 1,
-       CPU_PRI_CPUSET_INACTIVE = INT_MIN,
+       CPU_PRI_SCHED_INACTIVE  = INT_MIN,
 
        /* migration should happen before other stuff but after perf */
        CPU_PRI_PERF            = 20,

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 328502c..8a03a04 100644 (file)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5482,39 +5482,6 @@ static void set_cpu_rq_start_time(unsigned int cpu)
        rq->age_stamp = sched_clock_cpu(cpu);
 }
 
-static int sched_cpu_active(struct notifier_block *nfb,
-                                     unsigned long action, void *hcpu)
-{
-       int cpu = (long)hcpu;
-
-       switch (action & ~CPU_TASKS_FROZEN) {
-       case CPU_DOWN_FAILED:
-               set_cpu_active(cpu, true);
-               return NOTIFY_OK;
-
-       default:
-               return NOTIFY_DONE;
-       }
-}
-
-static int sched_cpu_inactive(struct notifier_block *nfb,
-                                       unsigned long action, void *hcpu)
-{
-       switch (action & ~CPU_TASKS_FROZEN) {
-       case CPU_DOWN_PREPARE:
-               set_cpu_active((long)hcpu, false);
-               return NOTIFY_OK;
-       default:
-               return NOTIFY_DONE;
-       }
-}
-
-int sched_cpu_starting(unsigned int cpu)
-{
-       set_cpu_rq_start_time(cpu);
-       return 0;
-}
-
 static cpumask_var_t sched_domains_tmpmask; /* sched_domains_mutex */
 
 #ifdef CONFIG_SCHED_DEBUG
@@ -6662,10 +6629,13 @@ static void sched_init_numa(void)
        init_numa_topology_type();
 }
 
-static void sched_domains_numa_masks_set(int cpu)
+static void sched_domains_numa_masks_set(unsigned int cpu)
 {
-       int i, j;
        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++) {
@@ -6675,54 +6645,23 @@ static void sched_domains_numa_masks_set(int cpu)
        }
 }
 
-static void sched_domains_numa_masks_clear(int cpu)
+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]);
        }
 }
 
-/*
- * Update sched_domains_numa_masks[level][node] array when new cpus
- * are onlined.
- */
-static int sched_domains_numa_masks_update(struct notifier_block *nfb,
-                                          unsigned long action,
-                                          void *hcpu)
-{
-       int cpu = (long)hcpu;
-
-       if (!sched_smp_initialized)
-               return NOTIFY_DONE;
-
-       switch (action & ~CPU_TASKS_FROZEN) {
-       case CPU_ONLINE:
-               sched_domains_numa_masks_set(cpu);
-               break;
-
-       case CPU_DEAD:
-               sched_domains_numa_masks_clear(cpu);
-               break;
-
-       default:
-               return NOTIFY_DONE;
-       }
-
-       return NOTIFY_OK;
-}
 #else
-static inline void sched_init_numa(void)
-{
-}
-
-static int sched_domains_numa_masks_update(struct notifier_block *nfb,
-                                          unsigned long action,
-                                          void *hcpu)
-{
-       return 0;
-}
+static inline void sched_init_numa(void) { }
+static void sched_domains_numa_masks_set(unsigned int cpu) { }
+static void sched_domains_numa_masks_clear(unsigned int cpu) { }
 #endif /* CONFIG_NUMA */
 
 static int __sdt_alloc(const struct cpumask *cpu_map)
@@ -7112,16 +7051,12 @@ 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 int cpuset_cpu_active(struct notifier_block *nfb, unsigned long action,
-                            void *hcpu)
+static void cpuset_cpu_active(bool frozen)
 {
        if (!sched_smp_initialized)
-               return NOTIFY_DONE;
-
-       switch (action) {
-       case CPU_ONLINE_FROZEN:
-       case CPU_DOWN_FAILED_FROZEN:
+               return;
 
+       if (frozen) {
                /*
                 * num_cpus_frozen tracks how many CPUs are involved in suspend
                 * resume sequence. As long as this is not the last online
@@ -7131,38 +7066,28 @@ static int cpuset_cpu_active(struct notifier_block *nfb, unsigned long action,
                num_cpus_frozen--;
                if (likely(num_cpus_frozen)) {
                        partition_sched_domains(1, NULL, NULL);
-                       break;
+                       return;
                }
-
                /*
                 * This is the last CPU online operation. So fall through and
                 * restore the original sched domains by considering the
                 * cpuset configurations.
                 */
-
-       case CPU_ONLINE:
-               cpuset_update_active_cpus(true);
-               break;
-       default:
-               return NOTIFY_DONE;
        }
-       return NOTIFY_OK;
+       cpuset_update_active_cpus(true);
 }
 
-static int cpuset_cpu_inactive(struct notifier_block *nfb, unsigned long action,
-                              void *hcpu)
+static int cpuset_cpu_inactive(unsigned int cpu, bool frozen)
 {
        unsigned long flags;
-       long cpu = (long)hcpu;
        struct dl_bw *dl_b;
        bool overflow;
        int cpus;
 
        if (!sched_smp_initialized)
-               return NOTIFY_DONE;
+               return 0;
 
-       switch (action) {
-       case CPU_DOWN_PREPARE:
+       if (!frozen) {
                rcu_read_lock_sched();
                dl_b = dl_bw_of(cpu);
 
@@ -7174,17 +7099,60 @@ static int cpuset_cpu_inactive(struct notifier_block *nfb, unsigned long action,
                rcu_read_unlock_sched();
 
                if (overflow)
-                       return notifier_from_errno(-EBUSY);
+                       return -EBUSY;
                cpuset_update_active_cpus(false);
-               break;
-       case CPU_DOWN_PREPARE_FROZEN:
+       } else {
                num_cpus_frozen++;
                partition_sched_domains(1, NULL, NULL);
-               break;
+       }
+       return 0;
+}
+
+static int sched_cpu_active(struct notifier_block *nfb, unsigned long action,
+                           void *hcpu)
+{
+       unsigned int cpu = (unsigned long)hcpu;
+
+       switch (action & ~CPU_TASKS_FROZEN) {
+       case CPU_DOWN_FAILED:
+       case CPU_ONLINE:
+               set_cpu_active(cpu, true);
+               sched_domains_numa_masks_set(cpu);
+               cpuset_cpu_active(action & CPU_TASKS_FROZEN);
+               return NOTIFY_OK;
        default:
                return NOTIFY_DONE;
        }
-       return NOTIFY_OK;
+}
+
+static int sched_cpu_inactive(struct notifier_block *nfb,
+                                       unsigned long action, void *hcpu)
+{
+       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);
+               }
+               return NOTIFY_OK;
+
+       case CPU_DEAD:
+               sched_domains_numa_masks_clear(cpu);
+               return NOTIFY_OK;
+       default:
+               return NOTIFY_DONE;
+       }
+}
+
+int sched_cpu_starting(unsigned int cpu)
+{
+       set_cpu_rq_start_time(cpu);
+       return 0;
 }
 
 void __init sched_init_smp(void)
@@ -7236,10 +7204,6 @@ static int __init migration_init(void)
        cpu_notifier(sched_cpu_active, CPU_PRI_SCHED_ACTIVE);
        cpu_notifier(sched_cpu_inactive, CPU_PRI_SCHED_INACTIVE);
 
-       hotcpu_notifier(sched_domains_numa_masks_update, CPU_PRI_SCHED_ACTIVE);
-       hotcpu_notifier(cpuset_cpu_active, CPU_PRI_CPUSET_ACTIVE);
-       hotcpu_notifier(cpuset_cpu_inactive, CPU_PRI_CPUSET_INACTIVE);
-
        return 0;
 }
 early_initcall(migration_init);