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cpu/hotplug: Create SMT sysfs interface for all arches

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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.

The 'control' file now shows 'notimplemented' for architectures which
don't yet have CONFIG_HOTPLUG_SMT.

[ tglx: Make notimplemented a real state ]

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Waiman Long <longman@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Jiri Kosina <jikos@kernel.org>
Link: https://lkml.kernel.org/r/469c2b98055f2c41e75748e06447d592a64080c9.1553635520.git.jpoimboe@redhat.com
This commit is contained in:
Josh Poimboeuf
2019-03-27 07:00:29 -05:00
committed by Thomas Gleixner
parent 79a3aaa7b8
commit de7b77e5bb
3 changed files with 47 additions and 30 deletions
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64
kernel/cpu.c
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@@ -2033,19 +2033,6 @@ 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);
@@ -2116,9 +2103,10 @@ 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;
@@ -2156,14 +2144,44 @@ 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);
@@ -2179,21 +2197,17 @@ 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;
@@ -2214,7 +2228,7 @@ 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