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SMP core updates: 

- Replace get/put_online_cpus() in various places. The final removal will
     happen shortly before v5.15-rc1 when the rest of the patches have been
     merged.
 
   - Add debug code to help the analysis of CPU hotplug failures
 
   - A set of kernel doc updates
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Merge tag 'smp-core-2021-08-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull SMP core updates from Thomas Gleixner:

 - Replace get/put_online_cpus() in various places. The final removal
   will happen shortly before v5.15-rc1 when the rest of the patches
   have been merged.

 - Add debug code to help the analysis of CPU hotplug failures

 - A set of kernel doc updates

* tag 'smp-core-2021-08-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  mm: Replace deprecated CPU-hotplug functions.
  md/raid5: Replace deprecated CPU-hotplug functions.
  Documentation: Replace deprecated CPU-hotplug functions.
  smp: Fix all kernel-doc warnings
  cpu/hotplug: Add debug printks for hotplug callback failures
  cpu/hotplug: Use DEVICE_ATTR_*() macro
  cpu/hotplug: Eliminate all kernel-doc warnings
  cpu/hotplug: Fix kernel doc warnings for __cpuhp_setup_state_cpuslocked()
  cpu/hotplug: Fix comment typo
  smpboot: Replace deprecated CPU-hotplug functions.
This commit is contained in:
Linus Torvalds 2021-08-30 14:10:07 -07:00
parent e4c3562e1b 7625eccd18
commit 08403e2174
9 changed files with 80 additions and 52 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
Documentation/core-api/cpu_hotplug.rst
View File

@ -220,7 +220,7 @@ goes online (offline) and during initial setup (shutdown) of the driver. However
each registration and removal function is also available with a ``_nocalls``
suffix which does not invoke the provided callbacks if the invocation of the
callbacks is not desired. During the manual setup (or teardown) the functions
``get_online_cpus()`` and ``put_online_cpus()`` should be used to inhibit CPU
``cpus_read_lock()`` and ``cpus_read_unlock()`` should be used to inhibit CPU
hotplug operations.

2
Documentation/trace/ftrace.rst
View File

@ -2762,7 +2762,7 @@ listed in:
put_prev_task_idle
kmem_cache_create
pick_next_task_rt
get_online_cpus
cpus_read_lock
pick_next_task_fair
mutex_lock
[...]

4
drivers/md/raid5.c
View File

@ -2437,7 +2437,7 @@ static int resize_chunks(struct r5conf *conf, int new_disks, int new_sectors)
conf->scribble_sectors >= new_sectors)
return 0;
mddev_suspend(conf->mddev);
get_online_cpus();
cpus_read_lock();
for_each_present_cpu(cpu) {
struct raid5_percpu *percpu;
@ -2449,7 +2449,7 @@ static int resize_chunks(struct r5conf *conf, int new_disks, int new_sectors)
break;
}
put_online_cpus();
cpus_read_unlock();
mddev_resume(conf->mddev);
if (!err) {
conf->scribble_disks = new_disks;

2
include/linux/cpuhotplug.h
View File

@ -399,7 +399,7 @@ static inline int cpuhp_state_remove_instance(enum cpuhp_state state,
/**
* cpuhp_state_remove_instance_nocalls - Remove hotplug instance from state
* without invoking the reatdown callback
* without invoking the teardown callback
* @state: The state from which the instance is removed
* @node: The node for this individual state.
*

84
kernel/cpu.c
View File

@ -41,14 +41,19 @@
#include "smpboot.h"
/**
* cpuhp_cpu_state - Per cpu hotplug state storage
* struct cpuhp_cpu_state - Per cpu hotplug state storage
* @state: The current cpu state
* @target: The target state
* @fail: Current CPU hotplug callback state
* @thread: Pointer to the hotplug thread
* @should_run: Thread should execute
* @rollback: Perform a rollback
* @single: Single callback invocation
* @bringup: Single callback bringup or teardown selector
* @cpu: CPU number
* @node: Remote CPU node; for multi-instance, do a
* single entry callback for install/remove
* @last: For multi-instance rollback, remember how far we got
* @cb_state: The state for a single callback (install/uninstall)
* @result: Result of the operation
* @done_up: Signal completion to the issuer of the task for cpu-up
@ -106,11 +111,12 @@ static inline void cpuhp_lock_release(bool bringup) { }
#endif
/**
* cpuhp_step - Hotplug state machine step
* struct cpuhp_step - Hotplug state machine step
* @name: Name of the step
* @startup: Startup function of the step
* @teardown: Teardown function of the step
* @cant_stop: Bringup/teardown can't be stopped at this step
* @multi_instance: State has multiple instances which get added afterwards
*/
struct cpuhp_step {
const char *name;
@ -124,7 +130,9 @@ struct cpuhp_step {
int (*multi)(unsigned int cpu,
struct hlist_node *node);
} teardown;
/* private: */
struct hlist_head list;
/* public: */
bool cant_stop;
bool multi_instance;
};
@ -143,7 +151,7 @@ static bool cpuhp_step_empty(bool bringup, struct cpuhp_step *step)
}
/**
* cpuhp_invoke_callback _ Invoke the callbacks for a given state
* cpuhp_invoke_callback - Invoke the callbacks for a given state
* @cpu: The cpu for which the callback should be invoked
* @state: The state to do callbacks for
* @bringup: True if the bringup callback should be invoked
@ -151,6 +159,8 @@ static bool cpuhp_step_empty(bool bringup, struct cpuhp_step *step)
* @lastp: For multi-instance rollback, remember how far we got
*
* Called from cpu hotplug and from the state register machinery.
*
* Return: %0 on success or a negative errno code
*/
static int cpuhp_invoke_callback(unsigned int cpu, enum cpuhp_state state,
bool bringup, struct hlist_node *node,
@ -682,6 +692,10 @@ static int cpuhp_up_callbacks(unsigned int cpu, struct cpuhp_cpu_state *st,
ret = cpuhp_invoke_callback_range(true, cpu, st, target);
if (ret) {
pr_debug("CPU UP failed (%d) CPU %u state %s (%d)\n",
ret, cpu, cpuhp_get_step(st->state)->name,
st->state);
cpuhp_reset_state(st, prev_state);
if (can_rollback_cpu(st))
WARN_ON(cpuhp_invoke_callback_range(false, cpu, st,
@ -1081,6 +1095,9 @@ static int cpuhp_down_callbacks(unsigned int cpu, struct cpuhp_cpu_state *st,
ret = cpuhp_invoke_callback_range(false, cpu, st, target);
if (ret) {
pr_debug("CPU DOWN failed (%d) CPU %u state %s (%d)\n",
ret, cpu, cpuhp_get_step(st->state)->name,
st->state);
cpuhp_reset_state(st, prev_state);
@ -1183,6 +1200,8 @@ static int cpu_down(unsigned int cpu, enum cpuhp_state target)
* This function is meant to be used by device core cpu subsystem only.
*
* Other subsystems should use remove_cpu() instead.
*
* Return: %0 on success or a negative errno code
*/
int cpu_device_down(struct device *dev)
{
@ -1395,6 +1414,8 @@ static int cpu_up(unsigned int cpu, enum cpuhp_state target)
* This function is meant to be used by device core cpu subsystem only.
*
* Other subsystems should use add_cpu() instead.
*
* Return: %0 on success or a negative errno code
*/
int cpu_device_up(struct device *dev)
{
@ -1420,6 +1441,8 @@ EXPORT_SYMBOL_GPL(add_cpu);
* On some architectures like arm64, we can hibernate on any CPU, but on
* wake up the CPU we hibernated on might be offline as a side effect of
* using maxcpus= for example.
*
* Return: %0 on success or a negative errno code
*/
int bringup_hibernate_cpu(unsigned int sleep_cpu)
{
@ -1976,6 +1999,7 @@ EXPORT_SYMBOL_GPL(__cpuhp_state_add_instance);
/**
* __cpuhp_setup_state_cpuslocked - Setup the callbacks for an hotplug machine state
* @state: The state to setup
* @name: Name of the step
* @invoke: If true, the startup function is invoked for cpus where
* cpu state >= @state
* @startup: startup callback function
@ -1984,9 +2008,9 @@ EXPORT_SYMBOL_GPL(__cpuhp_state_add_instance);
* added afterwards.
*
* The caller needs to hold cpus read locked while calling this function.
* Returns:
* Return:
* On success:
* Positive state number if @state is CPUHP_AP_ONLINE_DYN
* Positive state number if @state is CPUHP_AP_ONLINE_DYN;
* 0 for all other states
* On failure: proper (negative) error code
*/
@ -2232,18 +2256,17 @@ int cpuhp_smt_enable(void)
#endif
#if defined(CONFIG_SYSFS) && defined(CONFIG_HOTPLUG_CPU)
static ssize_t show_cpuhp_state(struct device *dev,
struct device_attribute *attr, char *buf)
static ssize_t state_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);
return sprintf(buf, "%d\n", st->state);
}
static DEVICE_ATTR(state, 0444, show_cpuhp_state, NULL);
static DEVICE_ATTR_RO(state);
static ssize_t write_cpuhp_target(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
static ssize_t target_store(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;
@ -2281,19 +2304,17 @@ static ssize_t write_cpuhp_target(struct device *dev,
return ret ? ret : count;
}
static ssize_t show_cpuhp_target(struct device *dev,
struct device_attribute *attr, char *buf)
static ssize_t target_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);
return sprintf(buf, "%d\n", st->target);
}
static DEVICE_ATTR(target, 0644, show_cpuhp_target, write_cpuhp_target);
static DEVICE_ATTR_RW(target);
static ssize_t write_cpuhp_fail(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
static ssize_t fail_store(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;
@ -2342,15 +2363,15 @@ static ssize_t write_cpuhp_fail(struct device *dev,
return count;
}
static ssize_t show_cpuhp_fail(struct device *dev,
struct device_attribute *attr, char *buf)
static ssize_t fail_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);
return sprintf(buf, "%d\n", st->fail);
}
static DEVICE_ATTR(fail, 0644, show_cpuhp_fail, write_cpuhp_fail);
static DEVICE_ATTR_RW(fail);
static struct attribute *cpuhp_cpu_attrs[] = {
&dev_attr_state.attr,
@ -2365,7 +2386,7 @@ static const struct attribute_group cpuhp_cpu_attr_group = {
NULL
};
static ssize_t show_cpuhp_states(struct device *dev,
static ssize_t states_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
ssize_t cur, res = 0;
@ -2384,7 +2405,7 @@ static ssize_t show_cpuhp_states(struct device *dev,
mutex_unlock(&cpuhp_state_mutex);
return res;
}
static DEVICE_ATTR(states, 0444, show_cpuhp_states, NULL);
static DEVICE_ATTR_RO(states);
static struct attribute *cpuhp_cpu_root_attrs[] = {
&dev_attr_states.attr,
@ -2457,28 +2478,27 @@ static const char *smt_states[] = {
[CPU_SMT_NOT_IMPLEMENTED] = "notimplemented",
};
static ssize_t
show_smt_control(struct device *dev, struct device_attribute *attr, char *buf)
static ssize_t control_show(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)
static ssize_t control_store(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 DEVICE_ATTR_RW(control);
static ssize_t
show_smt_active(struct device *dev, struct device_attribute *attr, char *buf)
static ssize_t active_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
return snprintf(buf, PAGE_SIZE - 2, "%d\n", sched_smt_active());
}
static DEVICE_ATTR(active, 0444, show_smt_active, NULL);
static DEVICE_ATTR_RO(active);
static struct attribute *cpuhp_smt_attrs[] = {
&dev_attr_control.attr,

14
kernel/smp.c
View File

@ -764,7 +764,7 @@ int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
EXPORT_SYMBOL(smp_call_function_single);
/**
* smp_call_function_single_async(): Run an asynchronous function on a
* smp_call_function_single_async() - Run an asynchronous function on a
* specific CPU.
* @cpu: The CPU to run on.
* @csd: Pre-allocated and setup data structure
@ -783,6 +783,8 @@ EXPORT_SYMBOL(smp_call_function_single);
*
* NOTE: Be careful, there is unfortunately no current debugging facility to
* validate the correctness of this serialization.
*
* Return: %0 on success or negative errno value on error
*/
int smp_call_function_single_async(int cpu, struct __call_single_data *csd)
{
@ -974,7 +976,7 @@ static void smp_call_function_many_cond(const struct cpumask *mask,
* @mask: The set of cpus to run on (only runs on online subset).
* @func: The function to run. This must be fast and non-blocking.
* @info: An arbitrary pointer to pass to the function.
* @flags: Bitmask that controls the operation. If %SCF_WAIT is set, wait
* @wait: Bitmask that controls the operation. If %SCF_WAIT is set, wait
* (atomically) until function has completed on other CPUs. If
* %SCF_RUN_LOCAL is set, the function will also be run locally
* if the local CPU is set in the @cpumask.
@ -1180,7 +1182,13 @@ void wake_up_all_idle_cpus(void)
EXPORT_SYMBOL_GPL(wake_up_all_idle_cpus);
/**
* smp_call_on_cpu - Call a function on a specific cpu
* struct smp_call_on_cpu_struct - Call a function on a specific CPU
* @work: &work_struct
* @done: &completion to signal
* @func: function to call
* @data: function's data argument
* @ret: return value from @func
* @cpu: target CPU (%-1 for any CPU)
*
* Used to call a function on a specific cpu and wait for it to return.
* Optionally make sure the call is done on a specified physical cpu via vcpu

8
kernel/smpboot.c
View File

@ -291,7 +291,7 @@ int smpboot_register_percpu_thread(struct smp_hotplug_thread *plug_thread)
unsigned int cpu;
int ret = 0;
get_online_cpus();
cpus_read_lock();
mutex_lock(&smpboot_threads_lock);
for_each_online_cpu(cpu) {
ret = __smpboot_create_thread(plug_thread, cpu);
@ -304,7 +304,7 @@ int smpboot_register_percpu_thread(struct smp_hotplug_thread *plug_thread)
list_add(&plug_thread->list, &hotplug_threads);
out:
mutex_unlock(&smpboot_threads_lock);
put_online_cpus();
cpus_read_unlock();
return ret;
}
EXPORT_SYMBOL_GPL(smpboot_register_percpu_thread);
@ -317,12 +317,12 @@ EXPORT_SYMBOL_GPL(smpboot_register_percpu_thread);
*/
void smpboot_unregister_percpu_thread(struct smp_hotplug_thread *plug_thread)
{
get_online_cpus();
cpus_read_lock();
mutex_lock(&smpboot_threads_lock);
list_del(&plug_thread->list);
smpboot_destroy_threads(plug_thread);
mutex_unlock(&smpboot_threads_lock);
put_online_cpus();
cpus_read_unlock();
}
EXPORT_SYMBOL_GPL(smpboot_unregister_percpu_thread);

4
mm/swap_slots.c
View File

@ -70,9 +70,9 @@ void disable_swap_slots_cache_lock(void)
swap_slot_cache_enabled = false;
if (swap_slot_cache_initialized) {
/* serialize with cpu hotplug operations */
get_online_cpus();
cpus_read_lock();
__drain_swap_slots_cache(SLOTS_CACHE|SLOTS_CACHE_RET);
put_online_cpus();
cpus_read_unlock();
}
}

12
mm/vmstat.c
View File

@ -129,9 +129,9 @@ static void sum_vm_events(unsigned long *ret)
*/
void all_vm_events(unsigned long *ret)
{
get_online_cpus();
cpus_read_lock();
sum_vm_events(ret);
put_online_cpus();
cpus_read_unlock();
}
EXPORT_SYMBOL_GPL(all_vm_events);
@ -1948,7 +1948,7 @@ static void vmstat_shepherd(struct work_struct *w)
{
int cpu;
get_online_cpus();
cpus_read_lock();
/* Check processors whose vmstat worker threads have been disabled */
for_each_online_cpu(cpu) {
struct delayed_work *dw = &per_cpu(vmstat_work, cpu);
@ -1958,7 +1958,7 @@ static void vmstat_shepherd(struct work_struct *w)
cond_resched();
}
put_online_cpus();
cpus_read_unlock();
schedule_delayed_work(&shepherd,
round_jiffies_relative(sysctl_stat_interval));
@ -2037,9 +2037,9 @@ void __init init_mm_internals(void)
if (ret < 0)
pr_err("vmstat: failed to register 'online' hotplug state\n");
get_online_cpus();
cpus_read_lock();
init_cpu_node_state();
put_online_cpus();
cpus_read_unlock();
start_shepherd_timer();
#endif