Currently cpuidle driver doesn't support cpu hotplug. When
cpus != maxcpus cpuidle_register() will fail to register all cpus
past the online ones and thus fail to register the idle driver.
This is because cpuidle_add_sysfs() will return with -ENODEV as a
consequence from get_cpu_device() return no device for a non-existing
CPU.
At least cpuidle-haltpoll and intel_idle are making their own custom
code to support cpu hotplug.
This patch ease the work if we need to write a cpuidle driver with cpu
hotplug support in the future.
Signed-off-by: Zhenzhong Duan <zhenzhong.d...@oracle.com>
---
drivers/cpuidle/cpuidle.c | 76 ++++++++++++++++++++++++++++++++---------------
1 file changed, 52 insertions(+), 24 deletions(-)
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index 0895b98..3ce6d2d 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -558,6 +558,51 @@ static void __cpuidle_device_init(struct cpuidle_device
*dev)
dev->next_hrtimer = 0;
}
+static int cpuidle_cpu_online(unsigned int cpu)
+{
+ int ret;
+ struct cpuidle_device *device;
+ struct cpuidle_driver *drv;
+
+ device = &per_cpu(cpuidle_dev, cpu);
+ device->cpu = cpu;
+
+ drv = cpuidle_get_cpu_driver(device);
+ if (!drv || !cpumask_test_cpu(cpu, drv->cpumask))
+ return 0;
+
+#ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED
+ /*
+ * On multiplatform for ARM, the coupled idle states could be
+ * enabled in the kernel even if the cpuidle driver does not
+ * use it. Note, coupled_cpus is a struct copy.
+ */
+ if (coupled_cpus)
+ device->coupled_cpus = *coupled_cpus;
+#endif
+ ret = cpuidle_register_device(device);
+ if (ret)
+ pr_err("Failed to register cpuidle device for cpu%d\n", cpu);
+
+ return ret;
+}
+
+static int cpuidle_cpu_offline(unsigned int cpu)
+{
+ struct cpuidle_device *device;
+ struct cpuidle_driver *drv;
+
+ device = &per_cpu(cpuidle_dev, cpu);
+
+ drv = cpuidle_get_cpu_driver(device);
+ if (!drv || !cpumask_test_cpu(cpu, drv->cpumask))
+ return 0;
+
+ cpuidle_unregister_device(device);
+
+ return 0;
+}
+
/**
* __cpuidle_register_device - internal register function called before
register
* and enable routines
@@ -690,8 +735,8 @@ void cpuidle_unregister(struct cpuidle_driver *drv)
int cpuidle_register(struct cpuidle_driver *drv,
const struct cpumask *const coupled_cpus)
{
- int ret, cpu;
- struct cpuidle_device *device;
+ int ret;
+ char cb_name[64];
ret = cpuidle_register_driver(drv);
if (ret) {
@@ -699,28 +744,11 @@ int cpuidle_register(struct cpuidle_driver *drv,
return ret;
}
- for_each_cpu(cpu, drv->cpumask) {
- device = &per_cpu(cpuidle_dev, cpu);
- device->cpu = cpu;
-
-#ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED
- /*
- * On multiplatform for ARM, the coupled idle states could be
- * enabled in the kernel even if the cpuidle driver does not
- * use it. Note, coupled_cpus is a struct copy.
- */
- if (coupled_cpus)
- device->coupled_cpus = *coupled_cpus;
-#endif
- ret = cpuidle_register_device(device);
- if (!ret)
- continue;
-
- pr_err("Failed to register cpuidle device for cpu%d\n", cpu);
-
- cpuidle_unregister(drv);
- break;
- }
+ sprintf(cb_name, "cpuidle/%s:online", drv->name);
+ ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, cb_name,
+ cpuidle_cpu_online, cpuidle_cpu_offline);
+ if (ret < 0)
+ cpuidle_unregister_driver(drv);
return ret;
}
--
1.8.3.1
