Commit 757c989b authored by Thomas Gleixner's avatar Thomas Gleixner

cpu/hotplug: Make target state writeable

Make it possible to write a target state to the per cpu state file, so we can
switch between states.
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: Rik van Riel <riel@redhat.com>
Cc: Rafael Wysocki <rafael.j.wysocki@intel.com>
Cc: "Srivatsa S. Bhat" <srivatsa@mit.edu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Turner <pjt@google.com>
Link: http://lkml.kernel.org/r/20160226182341.022814799@linutronix.deSigned-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 98f8cdce
...@@ -48,12 +48,14 @@ static DEFINE_PER_CPU(struct cpuhp_cpu_state, cpuhp_state); ...@@ -48,12 +48,14 @@ static DEFINE_PER_CPU(struct cpuhp_cpu_state, cpuhp_state);
* @teardown: Teardown function of the step * @teardown: Teardown function of the step
* @skip_onerr: Do not invoke the functions on error rollback * @skip_onerr: Do not invoke the functions on error rollback
* Will go away once the notifiers are gone * Will go away once the notifiers are gone
* @cant_stop: Bringup/teardown can't be stopped at this step
*/ */
struct cpuhp_step { struct cpuhp_step {
const char *name; const char *name;
int (*startup)(unsigned int cpu); int (*startup)(unsigned int cpu);
int (*teardown)(unsigned int cpu); int (*teardown)(unsigned int cpu);
bool skip_onerr; bool skip_onerr;
bool cant_stop;
}; };
static DEFINE_MUTEX(cpuhp_state_mutex); static DEFINE_MUTEX(cpuhp_state_mutex);
...@@ -558,7 +560,7 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen, ...@@ -558,7 +560,7 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen,
if (num_online_cpus() == 1) if (num_online_cpus() == 1)
return -EBUSY; return -EBUSY;
if (!cpu_online(cpu)) if (!cpu_present(cpu))
return -EINVAL; return -EINVAL;
cpu_hotplug_begin(); cpu_hotplug_begin();
...@@ -683,16 +685,25 @@ static int _cpu_up(unsigned int cpu, int tasks_frozen, enum cpuhp_state target) ...@@ -683,16 +685,25 @@ static int _cpu_up(unsigned int cpu, int tasks_frozen, enum cpuhp_state target)
cpu_hotplug_begin(); cpu_hotplug_begin();
if (cpu_online(cpu) || !cpu_present(cpu)) { if (!cpu_present(cpu)) {
ret = -EINVAL; ret = -EINVAL;
goto out; goto out;
} }
/* Let it fail before we try to bring the cpu up */ /*
idle = idle_thread_get(cpu); * The caller of do_cpu_up might have raced with another
if (IS_ERR(idle)) { * caller. Ignore it for now.
ret = PTR_ERR(idle); */
if (st->state >= target)
goto out; goto out;
if (st->state == CPUHP_OFFLINE) {
/* Let it fail before we try to bring the cpu up */
idle = idle_thread_get(cpu);
if (IS_ERR(idle)) {
ret = PTR_ERR(idle);
goto out;
}
} }
cpuhp_tasks_frozen = tasks_frozen; cpuhp_tasks_frozen = tasks_frozen;
...@@ -909,27 +920,32 @@ static struct cpuhp_step cpuhp_bp_states[] = { ...@@ -909,27 +920,32 @@ static struct cpuhp_step cpuhp_bp_states[] = {
.name = "threads:create", .name = "threads:create",
.startup = smpboot_create_threads, .startup = smpboot_create_threads,
.teardown = NULL, .teardown = NULL,
.cant_stop = true,
}, },
[CPUHP_NOTIFY_PREPARE] = { [CPUHP_NOTIFY_PREPARE] = {
.name = "notify:prepare", .name = "notify:prepare",
.startup = notify_prepare, .startup = notify_prepare,
.teardown = notify_dead, .teardown = notify_dead,
.skip_onerr = true, .skip_onerr = true,
.cant_stop = true,
}, },
[CPUHP_BRINGUP_CPU] = { [CPUHP_BRINGUP_CPU] = {
.name = "cpu:bringup", .name = "cpu:bringup",
.startup = bringup_cpu, .startup = bringup_cpu,
.teardown = NULL, .teardown = NULL,
.cant_stop = true,
}, },
[CPUHP_TEARDOWN_CPU] = { [CPUHP_TEARDOWN_CPU] = {
.name = "cpu:teardown", .name = "cpu:teardown",
.startup = NULL, .startup = NULL,
.teardown = takedown_cpu, .teardown = takedown_cpu,
.cant_stop = true,
}, },
[CPUHP_NOTIFY_ONLINE] = { [CPUHP_NOTIFY_ONLINE] = {
.name = "notify:online", .name = "notify:online",
.startup = notify_online, .startup = notify_online,
.teardown = notify_down_prepare, .teardown = notify_down_prepare,
.cant_stop = true,
}, },
#endif #endif
[CPUHP_ONLINE] = { [CPUHP_ONLINE] = {
...@@ -947,6 +963,7 @@ static struct cpuhp_step cpuhp_ap_states[] = { ...@@ -947,6 +963,7 @@ static struct cpuhp_step cpuhp_ap_states[] = {
.startup = notify_starting, .startup = notify_starting,
.teardown = notify_dying, .teardown = notify_dying,
.skip_onerr = true, .skip_onerr = true,
.cant_stop = true,
}, },
#endif #endif
[CPUHP_ONLINE] = { [CPUHP_ONLINE] = {
...@@ -979,6 +996,46 @@ static ssize_t show_cpuhp_state(struct device *dev, ...@@ -979,6 +996,46 @@ static ssize_t show_cpuhp_state(struct device *dev,
} }
static DEVICE_ATTR(state, 0444, show_cpuhp_state, NULL); static DEVICE_ATTR(state, 0444, show_cpuhp_state, NULL);
static ssize_t write_cpuhp_target(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);
struct cpuhp_step *sp;
int target, ret;
ret = kstrtoint(buf, 10, &target);
if (ret)
return ret;
#ifdef CONFIG_CPU_HOTPLUG_STATE_CONTROL
if (target < CPUHP_OFFLINE || target > CPUHP_ONLINE)
return -EINVAL;
#else
if (target != CPUHP_OFFLINE && target != CPUHP_ONLINE)
return -EINVAL;
#endif
ret = lock_device_hotplug_sysfs();
if (ret)
return ret;
mutex_lock(&cpuhp_state_mutex);
sp = cpuhp_get_step(target);
ret = !sp->name || sp->cant_stop ? -EINVAL : 0;
mutex_unlock(&cpuhp_state_mutex);
if (ret)
return ret;
if (st->state < target)
ret = do_cpu_up(dev->id, target);
else
ret = do_cpu_down(dev->id, target);
unlock_device_hotplug();
return ret ? ret : count;
}
static ssize_t show_cpuhp_target(struct device *dev, static ssize_t show_cpuhp_target(struct device *dev,
struct device_attribute *attr, char *buf) struct device_attribute *attr, char *buf)
{ {
...@@ -986,7 +1043,7 @@ static ssize_t show_cpuhp_target(struct device *dev, ...@@ -986,7 +1043,7 @@ static ssize_t show_cpuhp_target(struct device *dev,
return sprintf(buf, "%d\n", st->target); return sprintf(buf, "%d\n", st->target);
} }
static DEVICE_ATTR(target, 0444, show_cpuhp_target, NULL); static DEVICE_ATTR(target, 0644, show_cpuhp_target, write_cpuhp_target);
static struct attribute *cpuhp_cpu_attrs[] = { static struct attribute *cpuhp_cpu_attrs[] = {
&dev_attr_state.attr, &dev_attr_state.attr,
...@@ -1007,7 +1064,7 @@ static ssize_t show_cpuhp_states(struct device *dev, ...@@ -1007,7 +1064,7 @@ static ssize_t show_cpuhp_states(struct device *dev,
int i; int i;
mutex_lock(&cpuhp_state_mutex); mutex_lock(&cpuhp_state_mutex);
for (i = 0; i <= CPUHP_ONLINE; i++) { for (i = CPUHP_OFFLINE; i <= CPUHP_ONLINE; i++) {
struct cpuhp_step *sp = cpuhp_get_step(i); struct cpuhp_step *sp = cpuhp_get_step(i);
if (sp->name) { if (sp->name) {
......
...@@ -1442,6 +1442,19 @@ config DEBUG_BLOCK_EXT_DEVT ...@@ -1442,6 +1442,19 @@ config DEBUG_BLOCK_EXT_DEVT
Say N if you are unsure. Say N if you are unsure.
config CPU_HOTPLUG_STATE_CONTROL
bool "Enable CPU hotplug state control"
depends on DEBUG_KERNEL
depends on HOTPLUG_CPU
default n
help
Allows to write steps between "offline" and "online" to the CPUs
sysfs target file so states can be stepped granular. This is a debug
option for now as the hotplug machinery cannot be stopped and
restarted at arbitrary points yet.
Say N if your are unsure.
config NOTIFIER_ERROR_INJECTION config NOTIFIER_ERROR_INJECTION
tristate "Notifier error injection" tristate "Notifier error injection"
depends on DEBUG_KERNEL depends on DEBUG_KERNEL
......
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