Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 490 insertions, 0 deletions

diff --git a/kernel/smpboot.c b/kernel/smpboot.c
new file mode 100644
index 000000000..2c7396da4
--- /dev/null
+++ b/kernel/smpboot.c
@@ -0,0 +1,490 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Common SMP CPU bringup/teardown functions
+ */
+#include <linux/cpu.h>
+#include <linux/err.h>
+#include <linux/smp.h>
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include <linux/sched/task.h>
+#include <linux/export.h>
+#include <linux/percpu.h>
+#include <linux/kthread.h>
+#include <linux/smpboot.h>
+
+#include "smpboot.h"
+
+#ifdef CONFIG_SMP
+
+#ifdef CONFIG_GENERIC_SMP_IDLE_THREAD
+/*
+ * For the hotplug case we keep the task structs around and reuse
+ * them.
+ */
+static DEFINE_PER_CPU(struct task_struct *, idle_threads);
+
+struct task_struct *idle_thread_get(unsigned int cpu)
+{
+	struct task_struct *tsk = per_cpu(idle_threads, cpu);
+
+	if (!tsk)
+		return ERR_PTR(-ENOMEM);
+	return tsk;
+}
+
+void __init idle_thread_set_boot_cpu(void)
+{
+	per_cpu(idle_threads, smp_processor_id()) = current;
+}
+
+/**
+ * idle_init - Initialize the idle thread for a cpu
+ * @cpu:	The cpu for which the idle thread should be initialized
+ *
+ * Creates the thread if it does not exist.
+ */
+static __always_inline void idle_init(unsigned int cpu)
+{
+	struct task_struct *tsk = per_cpu(idle_threads, cpu);
+
+	if (!tsk) {
+		tsk = fork_idle(cpu);
+		if (IS_ERR(tsk))
+			pr_err("SMP: fork_idle() failed for CPU %u\n", cpu);
+		else
+			per_cpu(idle_threads, cpu) = tsk;
+	}
+}
+
+/**
+ * idle_threads_init - Initialize idle threads for all cpus
+ */
+void __init idle_threads_init(void)
+{
+	unsigned int cpu, boot_cpu;
+
+	boot_cpu = smp_processor_id();
+
+	for_each_possible_cpu(cpu) {
+		if (cpu != boot_cpu)
+			idle_init(cpu);
+	}
+}
+#endif
+
+#endif /* #ifdef CONFIG_SMP */
+
+static LIST_HEAD(hotplug_threads);
+static DEFINE_MUTEX(smpboot_threads_lock);
+
+struct smpboot_thread_data {
+	unsigned int			cpu;
+	unsigned int			status;
+	struct smp_hotplug_thread	*ht;
+};
+
+enum {
+	HP_THREAD_NONE = 0,
+	HP_THREAD_ACTIVE,
+	HP_THREAD_PARKED,
+};
+
+/**
+ * smpboot_thread_fn - percpu hotplug thread loop function
+ * @data:	thread data pointer
+ *
+ * Checks for thread stop and park conditions. Calls the necessary
+ * setup, cleanup, park and unpark functions for the registered
+ * thread.
+ *
+ * Returns 1 when the thread should exit, 0 otherwise.
+ */
+static int smpboot_thread_fn(void *data)
+{
+	struct smpboot_thread_data *td = data;
+	struct smp_hotplug_thread *ht = td->ht;
+
+	while (1) {
+		set_current_state(TASK_INTERRUPTIBLE);
+		preempt_disable();
+		if (kthread_should_stop()) {
+			__set_current_state(TASK_RUNNING);
+			preempt_enable();
+			/* cleanup must mirror setup */
+			if (ht->cleanup && td->status != HP_THREAD_NONE)
+				ht->cleanup(td->cpu, cpu_online(td->cpu));
+			kfree(td);
+			return 0;
+		}
+
+		if (kthread_should_park()) {
+			__set_current_state(TASK_RUNNING);
+			preempt_enable();
+			if (ht->park && td->status == HP_THREAD_ACTIVE) {
+				BUG_ON(td->cpu != smp_processor_id());
+				ht->park(td->cpu);
+				td->status = HP_THREAD_PARKED;
+			}
+			kthread_parkme();
+			/* We might have been woken for stop */
+			continue;
+		}
+
+		BUG_ON(td->cpu != smp_processor_id());
+
+		/* Check for state change setup */
+		switch (td->status) {
+		case HP_THREAD_NONE:
+			__set_current_state(TASK_RUNNING);
+			preempt_enable();
+			if (ht->setup)
+				ht->setup(td->cpu);
+			td->status = HP_THREAD_ACTIVE;
+			continue;
+
+		case HP_THREAD_PARKED:
+			__set_current_state(TASK_RUNNING);
+			preempt_enable();
+			if (ht->unpark)
+				ht->unpark(td->cpu);
+			td->status = HP_THREAD_ACTIVE;
+			continue;
+		}
+
+		if (!ht->thread_should_run(td->cpu)) {
+			preempt_enable_no_resched();
+			schedule();
+		} else {
+			__set_current_state(TASK_RUNNING);
+			preempt_enable();
+			ht->thread_fn(td->cpu);
+		}
+	}
+}
+
+static int
+__smpboot_create_thread(struct smp_hotplug_thread *ht, unsigned int cpu)
+{
+	struct task_struct *tsk = *per_cpu_ptr(ht->store, cpu);
+	struct smpboot_thread_data *td;
+
+	if (tsk)
+		return 0;
+
+	td = kzalloc_node(sizeof(*td), GFP_KERNEL, cpu_to_node(cpu));
+	if (!td)
+		return -ENOMEM;
+	td->cpu = cpu;
+	td->ht = ht;
+
+	tsk = kthread_create_on_cpu(smpboot_thread_fn, td, cpu,
+				    ht->thread_comm);
+	if (IS_ERR(tsk)) {
+		kfree(td);
+		return PTR_ERR(tsk);
+	}
+	kthread_set_per_cpu(tsk, cpu);
+	/*
+	 * Park the thread so that it could start right on the CPU
+	 * when it is available.
+	 */
+	kthread_park(tsk);
+	get_task_struct(tsk);
+	*per_cpu_ptr(ht->store, cpu) = tsk;
+	if (ht->create) {
+		/*
+		 * Make sure that the task has actually scheduled out
+		 * into park position, before calling the create
+		 * callback. At least the migration thread callback
+		 * requires that the task is off the runqueue.
+		 */
+		if (!wait_task_inactive(tsk, TASK_PARKED))
+			WARN_ON(1);
+		else
+			ht->create(cpu);
+	}
+	return 0;
+}
+
+int smpboot_create_threads(unsigned int cpu)
+{
+	struct smp_hotplug_thread *cur;
+	int ret = 0;
+
+	mutex_lock(&smpboot_threads_lock);
+	list_for_each_entry(cur, &hotplug_threads, list) {
+		ret = __smpboot_create_thread(cur, cpu);
+		if (ret)
+			break;
+	}
+	mutex_unlock(&smpboot_threads_lock);
+	return ret;
+}
+
+static void smpboot_unpark_thread(struct smp_hotplug_thread *ht, unsigned int cpu)
+{
+	struct task_struct *tsk = *per_cpu_ptr(ht->store, cpu);
+
+	if (!ht->selfparking)
+		kthread_unpark(tsk);
+}
+
+int smpboot_unpark_threads(unsigned int cpu)
+{
+	struct smp_hotplug_thread *cur;
+
+	mutex_lock(&smpboot_threads_lock);
+	list_for_each_entry(cur, &hotplug_threads, list)
+		smpboot_unpark_thread(cur, cpu);
+	mutex_unlock(&smpboot_threads_lock);
+	return 0;
+}
+
+static void smpboot_park_thread(struct smp_hotplug_thread *ht, unsigned int cpu)
+{
+	struct task_struct *tsk = *per_cpu_ptr(ht->store, cpu);
+
+	if (tsk && !ht->selfparking)
+		kthread_park(tsk);
+}
+
+int smpboot_park_threads(unsigned int cpu)
+{
+	struct smp_hotplug_thread *cur;
+
+	mutex_lock(&smpboot_threads_lock);
+	list_for_each_entry_reverse(cur, &hotplug_threads, list)
+		smpboot_park_thread(cur, cpu);
+	mutex_unlock(&smpboot_threads_lock);
+	return 0;
+}
+
+static void smpboot_destroy_threads(struct smp_hotplug_thread *ht)
+{
+	unsigned int cpu;
+
+	/* We need to destroy also the parked threads of offline cpus */
+	for_each_possible_cpu(cpu) {
+		struct task_struct *tsk = *per_cpu_ptr(ht->store, cpu);
+
+		if (tsk) {
+			kthread_stop(tsk);
+			put_task_struct(tsk);
+			*per_cpu_ptr(ht->store, cpu) = NULL;
+		}
+	}
+}
+
+/**
+ * smpboot_register_percpu_thread - Register a per_cpu thread related
+ * 					    to hotplug
+ * @plug_thread:	Hotplug thread descriptor
+ *
+ * Creates and starts the threads on all online cpus.
+ */
+int smpboot_register_percpu_thread(struct smp_hotplug_thread *plug_thread)
+{
+	unsigned int cpu;
+	int ret = 0;
+
+	cpus_read_lock();
+	mutex_lock(&smpboot_threads_lock);
+	for_each_online_cpu(cpu) {
+		ret = __smpboot_create_thread(plug_thread, cpu);
+		if (ret) {
+			smpboot_destroy_threads(plug_thread);
+			goto out;
+		}
+		smpboot_unpark_thread(plug_thread, cpu);
+	}
+	list_add(&plug_thread->list, &hotplug_threads);
+out:
+	mutex_unlock(&smpboot_threads_lock);
+	cpus_read_unlock();
+	return ret;
+}
+EXPORT_SYMBOL_GPL(smpboot_register_percpu_thread);
+
+/**
+ * smpboot_unregister_percpu_thread - Unregister a per_cpu thread related to hotplug
+ * @plug_thread:	Hotplug thread descriptor
+ *
+ * Stops all threads on all possible cpus.
+ */
+void smpboot_unregister_percpu_thread(struct smp_hotplug_thread *plug_thread)
+{
+	cpus_read_lock();
+	mutex_lock(&smpboot_threads_lock);
+	list_del(&plug_thread->list);
+	smpboot_destroy_threads(plug_thread);
+	mutex_unlock(&smpboot_threads_lock);
+	cpus_read_unlock();
+}
+EXPORT_SYMBOL_GPL(smpboot_unregister_percpu_thread);
+
+static DEFINE_PER_CPU(atomic_t, cpu_hotplug_state) = ATOMIC_INIT(CPU_POST_DEAD);
+
+/*
+ * Called to poll specified CPU's state, for example, when waiting for
+ * a CPU to come online.
+ */
+int cpu_report_state(int cpu)
+{
+	return atomic_read(&per_cpu(cpu_hotplug_state, cpu));
+}
+
+/*
+ * If CPU has died properly, set its state to CPU_UP_PREPARE and
+ * return success.  Otherwise, return -EBUSY if the CPU died after
+ * cpu_wait_death() timed out.  And yet otherwise again, return -EAGAIN
+ * if cpu_wait_death() timed out and the CPU still hasn't gotten around
+ * to dying.  In the latter two cases, the CPU might not be set up
+ * properly, but it is up to the arch-specific code to decide.
+ * Finally, -EIO indicates an unanticipated problem.
+ *
+ * Note that it is permissible to omit this call entirely, as is
+ * done in architectures that do no CPU-hotplug error checking.
+ */
+int cpu_check_up_prepare(int cpu)
+{
+	if (!IS_ENABLED(CONFIG_HOTPLUG_CPU)) {
+		atomic_set(&per_cpu(cpu_hotplug_state, cpu), CPU_UP_PREPARE);
+		return 0;
+	}
+
+	switch (atomic_read(&per_cpu(cpu_hotplug_state, cpu))) {
+
+	case CPU_POST_DEAD:
+
+		/* The CPU died properly, so just start it up again. */
+		atomic_set(&per_cpu(cpu_hotplug_state, cpu), CPU_UP_PREPARE);
+		return 0;
+
+	case CPU_DEAD_FROZEN:
+
+		/*
+		 * Timeout during CPU death, so let caller know.
+		 * The outgoing CPU completed its processing, but after
+		 * cpu_wait_death() timed out and reported the error. The
+		 * caller is free to proceed, in which case the state
+		 * will be reset properly by cpu_set_state_online().
+		 * Proceeding despite this -EBUSY return makes sense
+		 * for systems where the outgoing CPUs take themselves
+		 * offline, with no post-death manipulation required from
+		 * a surviving CPU.
+		 */
+		return -EBUSY;
+
+	case CPU_BROKEN:
+
+		/*
+		 * The most likely reason we got here is that there was
+		 * a timeout during CPU death, and the outgoing CPU never
+		 * did complete its processing.  This could happen on
+		 * a virtualized system if the outgoing VCPU gets preempted
+		 * for more than five seconds, and the user attempts to
+		 * immediately online that same CPU.  Trying again later
+		 * might return -EBUSY above, hence -EAGAIN.
+		 */
+		return -EAGAIN;
+
+	case CPU_UP_PREPARE:
+		/*
+		 * Timeout while waiting for the CPU to show up. Allow to try
+		 * again later.
+		 */
+		return 0;
+
+	default:
+
+		/* Should not happen.  Famous last words. */
+		return -EIO;
+	}
+}
+
+/*
+ * Mark the specified CPU online.
+ *
+ * Note that it is permissible to omit this call entirely, as is
+ * done in architectures that do no CPU-hotplug error checking.
+ */
+void cpu_set_state_online(int cpu)
+{
+	(void)atomic_xchg(&per_cpu(cpu_hotplug_state, cpu), CPU_ONLINE);
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+
+/*
+ * Wait for the specified CPU to exit the idle loop and die.
+ */
+bool cpu_wait_death(unsigned int cpu, int seconds)
+{
+	int jf_left = seconds * HZ;
+	int oldstate;
+	bool ret = true;
+	int sleep_jf = 1;
+
+	might_sleep();
+
+	/* The outgoing CPU will normally get done quite quickly. */
+	if (atomic_read(&per_cpu(cpu_hotplug_state, cpu)) == CPU_DEAD)
+		goto update_state_early;
+	udelay(5);
+
+	/* But if the outgoing CPU dawdles, wait increasingly long times. */
+	while (atomic_read(&per_cpu(cpu_hotplug_state, cpu)) != CPU_DEAD) {
+		schedule_timeout_uninterruptible(sleep_jf);
+		jf_left -= sleep_jf;
+		if (jf_left <= 0)
+			break;
+		sleep_jf = DIV_ROUND_UP(sleep_jf * 11, 10);
+	}
+update_state_early:
+	oldstate = atomic_read(&per_cpu(cpu_hotplug_state, cpu));
+update_state:
+	if (oldstate == CPU_DEAD) {
+		/* Outgoing CPU died normally, update state. */
+		smp_mb(); /* atomic_read() before update. */
+		atomic_set(&per_cpu(cpu_hotplug_state, cpu), CPU_POST_DEAD);
+	} else {
+		/* Outgoing CPU still hasn't died, set state accordingly. */
+		if (!atomic_try_cmpxchg(&per_cpu(cpu_hotplug_state, cpu),
+					&oldstate, CPU_BROKEN))
+			goto update_state;
+		ret = false;
+	}
+	return ret;
+}
+
+/*
+ * Called by the outgoing CPU to report its successful death.  Return
+ * false if this report follows the surviving CPU's timing out.
+ *
+ * A separate "CPU_DEAD_FROZEN" is used when the surviving CPU
+ * timed out.  This approach allows architectures to omit calls to
+ * cpu_check_up_prepare() and cpu_set_state_online() without defeating
+ * the next cpu_wait_death()'s polling loop.
+ */
+bool cpu_report_death(void)
+{
+	int oldstate;
+	int newstate;
+	int cpu = smp_processor_id();
+
+	oldstate = atomic_read(&per_cpu(cpu_hotplug_state, cpu));
+	do {
+		if (oldstate != CPU_BROKEN)
+			newstate = CPU_DEAD;
+		else
+			newstate = CPU_DEAD_FROZEN;
+	} while (!atomic_try_cmpxchg(&per_cpu(cpu_hotplug_state, cpu),
+				     &oldstate, newstate));
+	return newstate == CPU_DEAD;
+}
+
+#endif /* #ifdef CONFIG_HOTPLUG_CPU */