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Merge branch 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

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Pull CPU hotplug updates from Ingo Molnar:
 "Two changes in this cycle:

   - Make the /sys/devices/system/cpu/smt/* files available on all
     arches, so user space has a consistent way to detect whether SMT is
     enabled.

   - Sparse annotation fix"

* 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  smpboot: Place the __percpu annotation correctly
  cpu/hotplug: Create SMT sysfs interface for all arches
This commit is contained in:
Linus Torvalds 2019-05-06 14:44:49 -07:00
commit 5a2bf1abbf
4 changed files with 48 additions and 31 deletions
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10
Documentation/ABI/testing/sysfs-devices-system-cpu
View File

@ -511,10 +511,12 @@ Description: Control Symetric Multi Threading (SMT)
control: Read/write interface to control SMT. Possible
values:
"on" SMT is enabled
"off" SMT is disabled
"forceoff" SMT is force disabled. Cannot be changed.
"notsupported" SMT is not supported by the CPU
"on" SMT is enabled
"off" SMT is disabled
"forceoff" SMT is force disabled. Cannot be changed.
"notsupported" SMT is not supported by the CPU
"notimplemented" SMT runtime toggling is not
implemented for the architecture
If control status is "forceoff" or "notsupported" writes
are rejected.

3
include/linux/cpu.h
View File

@ -192,6 +192,7 @@ enum cpuhp_smt_control {
CPU_SMT_DISABLED,
CPU_SMT_FORCE_DISABLED,
CPU_SMT_NOT_SUPPORTED,
CPU_SMT_NOT_IMPLEMENTED,
};
#if defined(CONFIG_SMP) && defined(CONFIG_HOTPLUG_SMT)
@ -199,7 +200,7 @@ extern enum cpuhp_smt_control cpu_smt_control;
extern void cpu_smt_disable(bool force);
extern void cpu_smt_check_topology(void);
#else
# define cpu_smt_control (CPU_SMT_ENABLED)
# define cpu_smt_control (CPU_SMT_NOT_IMPLEMENTED)
static inline void cpu_smt_disable(bool force) { }
static inline void cpu_smt_check_topology(void) { }
#endif

2
include/linux/smpboot.h
View File

@ -29,7 +29,7 @@ struct smpboot_thread_data;
* @thread_comm: The base name of the thread
*/
struct smp_hotplug_thread {
struct task_struct __percpu **store;
struct task_struct * __percpu *store;
struct list_head list;
int (*thread_should_run)(unsigned int cpu);
void (*thread_fn)(unsigned int cpu);

64
kernel/cpu.c
View File

@ -2041,19 +2041,6 @@ static const struct attribute_group cpuhp_cpu_root_attr_group = {
#ifdef CONFIG_HOTPLUG_SMT
static const char *smt_states[] = {
[CPU_SMT_ENABLED] = "on",
[CPU_SMT_DISABLED] = "off",
[CPU_SMT_FORCE_DISABLED] = "forceoff",
[CPU_SMT_NOT_SUPPORTED] = "notsupported",
};
static ssize_t
show_smt_control(struct device *dev, struct device_attribute *attr, char *buf)
{
return snprintf(buf, PAGE_SIZE - 2, "%s\n", smt_states[cpu_smt_control]);
}
static void cpuhp_offline_cpu_device(unsigned int cpu)
{
struct device *dev = get_cpu_device(cpu);
@ -2124,9 +2111,10 @@ static int cpuhp_smt_enable(void)
return ret;
}
static ssize_t
store_smt_control(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
__store_smt_control(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
int ctrlval, ret;
@ -2164,14 +2152,44 @@ store_smt_control(struct device *dev, struct device_attribute *attr,
unlock_device_hotplug();
return ret ? ret : count;
}
#else /* !CONFIG_HOTPLUG_SMT */
static ssize_t
__store_smt_control(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
return -ENODEV;
}
#endif /* CONFIG_HOTPLUG_SMT */
static const char *smt_states[] = {
[CPU_SMT_ENABLED] = "on",
[CPU_SMT_DISABLED] = "off",
[CPU_SMT_FORCE_DISABLED] = "forceoff",
[CPU_SMT_NOT_SUPPORTED] = "notsupported",
[CPU_SMT_NOT_IMPLEMENTED] = "notimplemented",
};
static ssize_t
show_smt_control(struct device *dev, struct device_attribute *attr, char *buf)
{
const char *state = smt_states[cpu_smt_control];
return snprintf(buf, PAGE_SIZE - 2, "%s\n", state);
}
static ssize_t
store_smt_control(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
return __store_smt_control(dev, attr, buf, count);
}
static DEVICE_ATTR(control, 0644, show_smt_control, store_smt_control);
static ssize_t
show_smt_active(struct device *dev, struct device_attribute *attr, char *buf)
{
bool active = topology_max_smt_threads() > 1;
return snprintf(buf, PAGE_SIZE - 2, "%d\n", active);
return snprintf(buf, PAGE_SIZE - 2, "%d\n", sched_smt_active());
}
static DEVICE_ATTR(active, 0444, show_smt_active, NULL);
@ -2187,21 +2205,17 @@ static const struct attribute_group cpuhp_smt_attr_group = {
NULL
};
static int __init cpu_smt_state_init(void)
static int __init cpu_smt_sysfs_init(void)
{
return sysfs_create_group(&cpu_subsys.dev_root->kobj,
&cpuhp_smt_attr_group);
}
#else
static inline int cpu_smt_state_init(void) { return 0; }
#endif
static int __init cpuhp_sysfs_init(void)
{
int cpu, ret;
ret = cpu_smt_state_init();
ret = cpu_smt_sysfs_init();
if (ret)
return ret;
@ -2222,7 +2236,7 @@ static int __init cpuhp_sysfs_init(void)
return 0;
}
device_initcall(cpuhp_sysfs_init);
#endif
#endif /* CONFIG_SYSFS && CONFIG_HOTPLUG_CPU */
/*
* cpu_bit_bitmap[] is a special, "compressed" data structure that