linux-kernel - [PATCH 14/21] fault-injection: cpu: Convert to hotplug state machine

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Date:   Tue,  6 Sep 2016 19:04:50 +0200
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     linux-kernel@...r.kernel.org
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>, rt@...utronix.de,
        tglx@...utronix.de,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Akinobu Mita <akinobu.mita@...il.com>
Subject: [PATCH 14/21] fault-injection: cpu: Convert to hotplug state machine

Install the callbacks via the state machine.
This is just temporary. The longterm plan is to create a debugfs interface
where we can put the CPUs up and down from any given point to any given
point. So even if the conversations is not the prettiest - it is just
temporary.

Cc: Akinobu Mita <akinobu.mita@...il.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...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 0c33668d1626..4cbf88c955d6 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_X86_MICRCODE_PREPARE,
+	CPUHP_NOTF_ERR_INJ_PREPARE,
 	CPUHP_TIMERS_DEAD,
 	CPUHP_BRINGUP_CPU,
 	CPUHP_AP_IDLE_DEAD,
diff --git a/lib/cpu-notifier-error-inject.c b/lib/cpu-notifier-error-inject.c
index 707ca24f7b18..0e2c9a1e958a 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);
 }
 
-- 
2.9.3