[PATCH 16/16] powerpc: mmu nohash: Convert to hotplug state machine

[Sebastian Andrzej Siewior]

Install the callbacks via the state machine.

Cc: Benjamin Herrenschmidt <b...@kernel.crashing.org>
Cc: Paul Mackerras <pau...@samba.org>
Cc: Michael Ellerman <m...@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Sebastian Andrzej Siewior <bige...@linutronix.de>
---
 arch/powerpc/mm/mmu_context_nohash.c | 54 +++++++++++++++---------------------
 include/linux/cpuhotplug.h           |  1 +
 2 files changed, 24 insertions(+), 31 deletions(-)

diff --git a/arch/powerpc/mm/mmu_context_nohash.c 
b/arch/powerpc/mm/mmu_context_nohash.c
index 7d95bc402dba..f7755fcbe1f8 100644
--- a/arch/powerpc/mm/mmu_context_nohash.c
+++ b/arch/powerpc/mm/mmu_context_nohash.c
@@ -369,44 +369,34 @@ void destroy_context(struct mm_struct *mm)
 }
 
 #ifdef CONFIG_SMP
-
-static int mmu_context_cpu_notify(struct notifier_block *self,
-                                 unsigned long action, void *hcpu)
+static int mmu_ctx_cpu_prepare(unsigned int cpu)
 {
-       unsigned int cpu = (unsigned int)(long)hcpu;
-
        /* We don't touch CPU 0 map, it's allocated at aboot and kept
         * around forever
         */
        if (cpu == boot_cpuid)
-               return NOTIFY_OK;
+               return 0;
 
-       switch (action) {
-       case CPU_UP_PREPARE:
-       case CPU_UP_PREPARE_FROZEN:
-               pr_devel("MMU: Allocating stale context map for CPU %d\n", cpu);
-               stale_map[cpu] = kzalloc(CTX_MAP_SIZE, GFP_KERNEL);
-               break;
-#ifdef CONFIG_HOTPLUG_CPU
-       case CPU_UP_CANCELED:
-       case CPU_UP_CANCELED_FROZEN:
-       case CPU_DEAD:
-       case CPU_DEAD_FROZEN:
-               pr_devel("MMU: Freeing stale context map for CPU %d\n", cpu);
-               kfree(stale_map[cpu]);
-               stale_map[cpu] = NULL;
-
-               /* We also clear the cpu_vm_mask bits of CPUs going away */
-               clear_tasks_mm_cpumask(cpu);
-       break;
-#endif /* CONFIG_HOTPLUG_CPU */
-       }
-       return NOTIFY_OK;
+       pr_devel("MMU: Allocating stale context map for CPU %d\n", cpu);
+       stale_map[cpu] = kzalloc(CTX_MAP_SIZE, GFP_KERNEL);
+       return 0;
 }
 
-static struct notifier_block mmu_context_cpu_nb = {
-       .notifier_call  = mmu_context_cpu_notify,
-};
+static int mmu_ctx_cpu_dead(unsigned int cpu)
+{
+#ifdef CONFIG_HOTPLUG_CPU
+       if (cpu == boot_cpuid)
+               return 0;
+
+       pr_devel("MMU: Freeing stale context map for CPU %d\n", cpu);
+       kfree(stale_map[cpu]);
+       stale_map[cpu] = NULL;
+
+       /* We also clear the cpu_vm_mask bits of CPUs going away */
+       clear_tasks_mm_cpumask(cpu);
+#endif
+       return 0;
+}
 
 #endif /* CONFIG_SMP */
 
@@ -469,7 +459,9 @@ void __init mmu_context_init(void)
 #else
        stale_map[boot_cpuid] = memblock_virt_alloc(CTX_MAP_SIZE, 0);
 
-       register_cpu_notifier(&mmu_context_cpu_nb);
+       cpuhp_setup_state_nocalls(CPUHP_POWER_MMU_CTX_PREPARE,
+                                 "POWER_MMU_CTX_PREPARE", mmu_ctx_cpu_prepare,
+                                 mmu_ctx_cpu_dead);
 #endif
 
        printk(KERN_INFO
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 4974c9fdbf9a..92b9cf3271b2 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -33,6 +33,7 @@ enum cpuhp_state {
        CPUHP_MD_RAID5_PREPARE,
        CPUHP_CPUIDLE_COUPLED_PREPARE,
        CPUHP_POWER_PMAC_PREPARE,
+       CPUHP_POWER_MMU_CTX_PREPARE,
        CPUHP_NOTIFY_PREPARE,
        CPUHP_TIMERS_DEAD,
        CPUHP_BRINGUP_CPU,
-- 
2.9.3