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 <[email protected]>
---
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
Hi Zhenzhong,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on pm/linux-next]
[cannot apply to v5.4-rc2 next-20191011]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]
url: https://github.com/0day-ci/linux/commits/Zhenzhong-Duan/cpuidle-cpu-hotplug-support/20191014-000932
base: https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git linux-next
config: mips-allmodconfig (attached as .config)
compiler: mips-linux-gcc (GCC) 7.4.0
reproduce:
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# save the attached .config to linux build tree
GCC_VERSION=7.4.0 make.cross ARCH=mips
If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <[email protected]>
All errors (new ones prefixed by >>):
drivers/cpuidle/cpuidle.c: In function 'cpuidle_cpu_online':
>> drivers/cpuidle/cpuidle.c:580:6: error: 'coupled_cpus' undeclared (first use in this function); did you mean 'total_cpus'?
if (coupled_cpus)
^~~~~~~~~~~~
total_cpus
drivers/cpuidle/cpuidle.c:580:6: note: each undeclared identifier is reported only once for each function it appears in
vim +580 drivers/cpuidle/cpuidle.c
560
561 static int cpuidle_cpu_online(unsigned int cpu)
562 {
563 int ret;
564 struct cpuidle_device *device;
565 struct cpuidle_driver *drv;
566
567 device = &per_cpu(cpuidle_dev, cpu);
568 device->cpu = cpu;
569
570 drv = cpuidle_get_cpu_driver(device);
571 if (!drv || !cpumask_test_cpu(cpu, drv->cpumask))
572 return 0;
573
574 #ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED
575 /*
576 * On multiplatform for ARM, the coupled idle states could be
577 * enabled in the kernel even if the cpuidle driver does not
578 * use it. Note, coupled_cpus is a struct copy.
579 */
> 580 if (coupled_cpus)
581 device->coupled_cpus = *coupled_cpus;
582 #endif
583 ret = cpuidle_register_device(device);
584 if (ret)
585 pr_err("Failed to register cpuidle device for cpu%d\n", cpu);
586
587 return ret;
588 }
589
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation