linux-kernel - [PATCH 12/25] drivers base/cacheinfo: Convert to hotplug state machine

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Date:   Thu,  3 Nov 2016 15:50:08 +0100
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     linux-kernel@...r.kernel.org
Cc:     rt@...utronix.de,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: [PATCH 12/25] drivers base/cacheinfo: Convert to hotplug state machine

Install the callbacks via the state machine and let the core invoke
the callbacks on the already online CPUs. No functional change.

Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
 drivers/base/cacheinfo.c | 57 +++++++++++++-----------------------------------
 1 file changed, 15 insertions(+), 42 deletions(-)

diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c
index e9fd32e91668..47983a2ba621 100644
--- a/drivers/base/cacheinfo.c
+++ b/drivers/base/cacheinfo.c
@@ -498,57 +498,30 @@ static int cache_add_dev(unsigned int cpu)
 	return rc;
 }
 
-static void cache_remove_dev(unsigned int cpu)
+static int cacheinfo_cpu_online(unsigned int cpu)
 {
-	if (!cpumask_test_cpu(cpu, &cache_dev_map))
-		return;
-	cpumask_clear_cpu(cpu, &cache_dev_map);
+	int rc = detect_cache_attributes(cpu);
 
-	cpu_cache_sysfs_exit(cpu);
+	if (rc)
+		return rc;
+	rc = cache_add_dev(cpu);
+	if (rc)
+		free_cache_attributes(cpu);
+	return rc;
 }
 
-static int cacheinfo_cpu_callback(struct notifier_block *nfb,
-				  unsigned long action, void *hcpu)
+static int cacheinfo_cpu_pre_down(unsigned int cpu)
 {
-	unsigned int cpu = (unsigned long)hcpu;
-	int rc = 0;
+	if (cpumask_test_and_clear_cpu(cpu, &cache_dev_map))
+		cpu_cache_sysfs_exit(cpu);
 
-	switch (action & ~CPU_TASKS_FROZEN) {
-	case CPU_ONLINE:
-		rc = detect_cache_attributes(cpu);
-		if (!rc)
-			rc = cache_add_dev(cpu);
-		break;
-	case CPU_DEAD:
-		cache_remove_dev(cpu);
-		free_cache_attributes(cpu);
-		break;
-	}
-	return notifier_from_errno(rc);
+	free_cache_attributes(cpu);
+	return 0;
 }
 
 static int __init cacheinfo_sysfs_init(void)
 {
-	int cpu, rc = 0;
-
-	cpu_notifier_register_begin();
-
-	for_each_online_cpu(cpu) {
-		rc = detect_cache_attributes(cpu);
-		if (rc)
-			goto out;
-		rc = cache_add_dev(cpu);
-		if (rc) {
-			free_cache_attributes(cpu);
-			pr_err("error populating cacheinfo..cpu%d\n", cpu);
-			goto out;
-		}
-	}
-	__hotcpu_notifier(cacheinfo_cpu_callback, 0);
-
-out:
-	cpu_notifier_register_done();
-	return rc;
+	return cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "base/cacheinfo:online",
+				 cacheinfo_cpu_online, cacheinfo_cpu_pre_down);
 }
-
 device_initcall(cacheinfo_sysfs_init);
-- 
2.10.2