Commit 08403e21 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

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.
parents e4c3562e 7625eccd

Documentation/core-api/cpu_hotplug.rst

+1 −1
Original line number Diff line number Diff line
@@ -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.

Documentation/trace/ftrace.rst

+1 −1
Original line number Diff line number Diff line
@@ -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

  [...]

drivers/md/raid5.c

+2 −2
Original line number Diff line number Diff line
@@ -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;

include/linux/cpuhotplug.h

+1 −1
Original line number Diff line number Diff line
@@ -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.

 *

kernel/cpu.c

+52 −32
Original line number Diff line number Diff line
@@ -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

 */
@@ -2232,17 +2256,16 @@ int cpuhp_smt_enable(void) 
#endif



#if defined(CONFIG_SYSFS) && defined(CONFIG_HOTPLUG_CPU)

static ssize_t show_cpuhp_state(struct device *dev,

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,

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);
@@ -2281,18 +2304,16 @@ static ssize_t write_cpuhp_target(struct device *dev, 
	return ret ? ret : count;

}



static ssize_t show_cpuhp_target(struct device *dev,

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,

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);
@@ -2342,7 +2363,7 @@ static ssize_t write_cpuhp_fail(struct device *dev, 
	return count;

}



static ssize_t show_cpuhp_fail(struct device *dev,

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);
@@ -2350,7 +2371,7 @@ static ssize_t show_cpuhp_fail(struct device *dev, 
	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,

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,