linux-kernel - [tip:smp/hotplug] fault-injection/cpu: Convert to hotplug state machine

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Date:   Mon, 19 Sep 2016 12:57:48 -0700
From:   tip-bot for Sebastian Andrzej Siewior <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     peterz@...radead.org, linux-kernel@...r.kernel.org,
        mingo@...nel.org, akinobu.mita@...il.com, bigeasy@...utronix.de,
        tglx@...utronix.de, hpa@...or.com
Subject: [tip:smp/hotplug] fault-injection/cpu: Convert to hotplug state
 machine

Commit-ID:  8c58898b3ecb213ad7c52aa0c7c9d3201e559be1
Gitweb:     http://git.kernel.org/tip/8c58898b3ecb213ad7c52aa0c7c9d3201e559be1
Author:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>
AuthorDate: Tue, 6 Sep 2016 19:04:50 +0200
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Mon, 19 Sep 2016 21:44:31 +0200

fault-injection/cpu: Convert to hotplug state machine

Install the callbacks via the state machine.

This is just a temporary vehicle to keep the interface working for now,
It'll be replaced by the sysfs interface which allows to step through the
hotplug state machine step by step.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Akinobu Mita <akinobu.mita@...il.com>
Cc: rt@...utronix.de
Link: http://lkml.kernel.org/r/20160906170457.32393-15-bigeasy@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>

---
 include/linux/cpuhotplug.h      |  1 +
 lib/cpu-notifier-error-inject.c | 46 +++++++++++++++++++++++++++++++++++------
 2 files changed, 41 insertions(+), 6 deletions(-)

diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 7706987..bb6231d 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -43,6 +43,7 @@ enum cpuhp_state {
 	CPUHP_ARM_SHMOBILE_SCU_PREPARE,
 	CPUHP_SH_SH3X_PREPARE,
 	CPUHP_TIMERS_DEAD,
+	CPUHP_NOTF_ERR_INJ_PREPARE,
 	CPUHP_BRINGUP_CPU,
 	CPUHP_AP_IDLE_DEAD,
 	CPUHP_AP_OFFLINE,
diff --git a/lib/cpu-notifier-error-inject.c b/lib/cpu-notifier-error-inject.c
index 707ca24..0e2c9a1 100644
--- a/lib/cpu-notifier-error-inject.c
+++ b/lib/cpu-notifier-error-inject.c
@@ -8,16 +8,47 @@ static int priority;
 module_param(priority, int, 0);
 MODULE_PARM_DESC(priority, "specify cpu notifier priority");
 
+#define UP_PREPARE 0
+#define UP_PREPARE_FROZEN 0
+#define DOWN_PREPARE 0
+#define DOWN_PREPARE_FROZEN 0
+
 static struct notifier_err_inject cpu_notifier_err_inject = {
 	.actions = {
-		{ NOTIFIER_ERR_INJECT_ACTION(CPU_UP_PREPARE) },
-		{ NOTIFIER_ERR_INJECT_ACTION(CPU_UP_PREPARE_FROZEN) },
-		{ NOTIFIER_ERR_INJECT_ACTION(CPU_DOWN_PREPARE) },
-		{ NOTIFIER_ERR_INJECT_ACTION(CPU_DOWN_PREPARE_FROZEN) },
+		{ NOTIFIER_ERR_INJECT_ACTION(UP_PREPARE) },
+		{ NOTIFIER_ERR_INJECT_ACTION(UP_PREPARE_FROZEN) },
+		{ NOTIFIER_ERR_INJECT_ACTION(DOWN_PREPARE) },
+		{ NOTIFIER_ERR_INJECT_ACTION(DOWN_PREPARE_FROZEN) },
 		{}
 	}
 };
 
+static int notf_err_handle(struct notifier_err_inject_action *action)
+{
+	int ret;
+
+	ret = action->error;
+	if (ret)
+		pr_info("Injecting error (%d) to %s\n", ret, action->name);
+	return ret;
+}
+
+static int notf_err_inj_up_prepare(unsigned int cpu)
+{
+	if (!cpuhp_tasks_frozen)
+		return notf_err_handle(&cpu_notifier_err_inject.actions[0]);
+	else
+		return notf_err_handle(&cpu_notifier_err_inject.actions[1]);
+}
+
+static int notf_err_inj_dead(unsigned int cpu)
+{
+	if (!cpuhp_tasks_frozen)
+		return notf_err_handle(&cpu_notifier_err_inject.actions[2]);
+	else
+		return notf_err_handle(&cpu_notifier_err_inject.actions[3]);
+}
+
 static struct dentry *dir;
 
 static int err_inject_init(void)
@@ -29,7 +60,10 @@ static int err_inject_init(void)
 	if (IS_ERR(dir))
 		return PTR_ERR(dir);
 
-	err = register_hotcpu_notifier(&cpu_notifier_err_inject.nb);
+	err = cpuhp_setup_state_nocalls(CPUHP_NOTF_ERR_INJ_PREPARE,
+					"cpu-err-notif:prepare",
+					notf_err_inj_up_prepare,
+					notf_err_inj_dead);
 	if (err)
 		debugfs_remove_recursive(dir);
 
@@ -38,7 +72,7 @@ static int err_inject_init(void)
 
 static void err_inject_exit(void)
 {
-	unregister_hotcpu_notifier(&cpu_notifier_err_inject.nb);
+	cpuhp_remove_state_nocalls(CPUHP_NOTF_ERR_INJ_PREPARE);
 	debugfs_remove_recursive(dir);
 }