padata: Convert to hotplug state machine

Install the callbacks via the state machine. CPU-hotplug multinstance support
is used with the nocalls() version. Maybe parts of padata_alloc() could be
moved into the online callback so that we could invoke ->startup callback for
instance and drop get_online_cpus().

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-crypto@vger.kernel.org
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160906170457.32393-14-bigeasy@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

2 files changed, 51 insertions, 39 deletions

diff --git a/include/linux/padata.h b/include/linux/padata.h
index 113ee626a4dc..0f9e567d5e15 100644
--- a/include/linux/padata.h
+++ b/include/linux/padata.h
@@ -151,7 +151,7 @@ struct parallel_data {
  * @flags: padata flags.
  */
 struct padata_instance {
-        struct notifier_block            cpu_notifier;
+        struct hlist_node                node;
         struct workqueue_struct         *wq;
         struct parallel_data            *pd;
         struct padata_cpumask           cpumask;
diff --git a/kernel/padata.c b/kernel/padata.c
index 993278895ccc..7848f0566403 100644
--- a/kernel/padata.c
+++ b/kernel/padata.c
@@ -30,6 +30,7 @@
 #include <linux/slab.h>
 #include <linux/sysfs.h>
 #include <linux/rcupdate.h>
+#include <linux/module.h>
 
 #define MAX_OBJ_NUM 1000
 
@@ -769,52 +770,43 @@ static inline int pinst_has_cpu(struct padata_instance *pinst, int cpu)
                 cpumask_test_cpu(cpu, pinst->cpumask.cbcpu);
 }
 
-
-static int padata_cpu_callback(struct notifier_block *nfb,
-                               unsigned long action, void *hcpu)
+static int padata_cpu_online(unsigned int cpu, struct hlist_node *node)
 {
-        int err;
         struct padata_instance *pinst;
-        int cpu = (unsigned long)hcpu;
+        int ret;
 
-        pinst = container_of(nfb, struct padata_instance, cpu_notifier);
+        pinst = hlist_entry_safe(node, struct padata_instance, node);
+        if (!pinst_has_cpu(pinst, cpu))
+                return 0;
 
-        switch (action) {
-        case CPU_ONLINE:
-        case CPU_ONLINE_FROZEN:
-        case CPU_DOWN_FAILED:
-        case CPU_DOWN_FAILED_FROZEN:
-                if (!pinst_has_cpu(pinst, cpu))
-                        break;
-                mutex_lock(&pinst->lock);
-                err = __padata_add_cpu(pinst, cpu);
-                mutex_unlock(&pinst->lock);
-                if (err)
-                        return notifier_from_errno(err);
-                break;
+        mutex_lock(&pinst->lock);
+        ret = __padata_add_cpu(pinst, cpu);
+        mutex_unlock(&pinst->lock);
+        return ret;
+}
 
-        case CPU_DOWN_PREPARE:
-        case CPU_DOWN_PREPARE_FROZEN:
-        case CPU_UP_CANCELED:
-        case CPU_UP_CANCELED_FROZEN:
-                if (!pinst_has_cpu(pinst, cpu))
-                        break;
-                mutex_lock(&pinst->lock);
-                err = __padata_remove_cpu(pinst, cpu);
-                mutex_unlock(&pinst->lock);
-                if (err)
-                        return notifier_from_errno(err);
-                break;
-        }
+static int padata_cpu_prep_down(unsigned int cpu, struct hlist_node *node)
+{
+        struct padata_instance *pinst;
+        int ret;
+
+        pinst = hlist_entry_safe(node, struct padata_instance, node);
+        if (!pinst_has_cpu(pinst, cpu))
+                return 0;
 
-        return NOTIFY_OK;
+        mutex_lock(&pinst->lock);
+        ret = __padata_remove_cpu(pinst, cpu);
+        mutex_unlock(&pinst->lock);
+        return ret;
 }
+
+static enum cpuhp_state hp_online;
 #endif
 
 static void __padata_free(struct padata_instance *pinst)
 {
 #ifdef CONFIG_HOTPLUG_CPU
-        unregister_hotcpu_notifier(&pinst->cpu_notifier);
+        cpuhp_state_remove_instance_nocalls(hp_online, &pinst->node);
 #endif
 
         padata_stop(pinst);
@@ -1012,11 +1004,8 @@ struct padata_instance *padata_alloc(struct workqueue_struct *wq,
         mutex_init(&pinst->lock);
 
 #ifdef CONFIG_HOTPLUG_CPU
-        pinst->cpu_notifier.notifier_call = padata_cpu_callback;
-        pinst->cpu_notifier.priority = 0;
-        register_hotcpu_notifier(&pinst->cpu_notifier);
+        cpuhp_state_add_instance_nocalls(hp_online, &pinst->node);
 #endif
-
         return pinst;
 
 err_free_masks:
@@ -1039,3 +1028,26 @@ void padata_free(struct padata_instance *pinst)
         kobject_put(&pinst->kobj);
 }
 EXPORT_SYMBOL(padata_free);
+
+#ifdef CONFIG_HOTPLUG_CPU
+
+static __init int padata_driver_init(void)
+{
+        int ret;
+
+        ret = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN, "padata:online",
+                                      padata_cpu_online,
+                                      padata_cpu_prep_down);
+        if (ret < 0)
+                return ret;
+        hp_online = ret;
+        return 0;
+}
+module_init(padata_driver_init);
+
+static __exit void padata_driver_exit(void)
+{
+        cpuhp_remove_multi_state(hp_online);
+}
+module_exit(padata_driver_exit);
+#endif