Orange Pi5 kernel

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2010 Red Hat, Inc., Peter Zijlstra
 *
 * Provides a framework for enqueueing and running callbacks from hardirq
 * context. The enqueueing is NMI-safe.
 */
 
#include <linux/bug.h>
#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/irq_work.h>
#include <linux/percpu.h>
#include <linux/hardirq.h>
#include <linux/irqflags.h>
#include <linux/sched.h>
#include <linux/tick.h>
#include <linux/cpu.h>
#include <linux/notifier.h>
#include <linux/smp.h>
#include <asm/processor.h>
 
 
static DEFINE_PER_CPU(struct llist_head, raised_list);
static DEFINE_PER_CPU(struct llist_head, lazy_list);
 
/*
 * Claim the entry so that no one else will poke at it.
 */
static bool irq_work_claim(struct irq_work *work)
{
<------>int oflags;
 
<------>oflags = atomic_fetch_or(IRQ_WORK_CLAIMED | CSD_TYPE_IRQ_WORK, &work->flags);
<------>/*
<------> * If the work is already pending, no need to raise the IPI.
<------> * The pairing atomic_fetch_andnot() in irq_work_run() makes sure
<------> * everything we did before is visible.
<------> */
<------>if (oflags & IRQ_WORK_PENDING)
<------><------>return false;
<------>return true;
}
 
void __weak arch_irq_work_raise(void)
{
<------>/*
<------> * Lame architectures will get the timer tick callback
<------> */
}
 
/* Enqueue on current CPU, work must already be claimed and preempt disabled */
static void __irq_work_queue_local(struct irq_work *work)
{
<------>/* If the work is "lazy", handle it from next tick if any */
<------>if (atomic_read(&work->flags) & IRQ_WORK_LAZY) {
<------><------>if (llist_add(&work->llnode, this_cpu_ptr(&lazy_list)) &&
<------><------>    tick_nohz_tick_stopped())
<------><------><------>arch_irq_work_raise();
<------>} else {
<------><------>if (llist_add(&work->llnode, this_cpu_ptr(&raised_list)))
<------><------><------>arch_irq_work_raise();
<------>}
}
 
/* Enqueue the irq work @work on the current CPU */
bool irq_work_queue(struct irq_work *work)
{
<------>/* Only queue if not already pending */
<------>if (!irq_work_claim(work))
<------><------>return false;
 
<------>/* Queue the entry and raise the IPI if needed. */
<------>preempt_disable();
<------>__irq_work_queue_local(work);
<------>preempt_enable();
 
<------>return true;
}
EXPORT_SYMBOL_GPL(irq_work_queue);
 
/*
 * Enqueue the irq_work @work on @cpu unless it's already pending
 * somewhere.
 *
 * Can be re-enqueued while the callback is still in progress.
 */
bool irq_work_queue_on(struct irq_work *work, int cpu)
{
#ifndef CONFIG_SMP
<------>return irq_work_queue(work);
 
#else /* CONFIG_SMP: */
<------>/* All work should have been flushed before going offline */
<------>WARN_ON_ONCE(cpu_is_offline(cpu));
 
<------>/* Only queue if not already pending */
<------>if (!irq_work_claim(work))
<------><------>return false;
 
<------>preempt_disable();
<------>if (cpu != smp_processor_id()) {
<------><------>/* Arch remote IPI send/receive backend aren't NMI safe */
<------><------>WARN_ON_ONCE(in_nmi());
<------><------>__smp_call_single_queue(cpu, &work->llnode);
<------>} else {
<------><------>__irq_work_queue_local(work);
<------>}
<------>preempt_enable();
 
<------>return true;
#endif /* CONFIG_SMP */
}
EXPORT_SYMBOL_GPL(irq_work_queue_on);
 
bool irq_work_needs_cpu(void)
{
<------>struct llist_head *raised, *lazy;
 
<------>raised = this_cpu_ptr(&raised_list);
<------>lazy = this_cpu_ptr(&lazy_list);
 
<------>if (llist_empty(raised) || arch_irq_work_has_interrupt())
<------><------>if (llist_empty(lazy))
<------><------><------>return false;
 
<------>/* All work should have been flushed before going offline */
<------>WARN_ON_ONCE(cpu_is_offline(smp_processor_id()));
 
<------>return true;
}
 
void irq_work_single(void *arg)
{
<------>struct irq_work *work = arg;
<------>int flags;
 
<------>/*
<------> * Clear the PENDING bit, after this point the @work
<------> * can be re-used.
<------> * Make it immediately visible so that other CPUs trying
<------> * to claim that work don't rely on us to handle their data
<------> * while we are in the middle of the func.
<------> */
<------>flags = atomic_fetch_andnot(IRQ_WORK_PENDING, &work->flags);
 
<------>lockdep_irq_work_enter(work);
<------>work->func(work);
<------>lockdep_irq_work_exit(work);
<------>/*
<------> * Clear the BUSY bit and return to the free state if
<------> * no-one else claimed it meanwhile.
<------> */
<------>flags &= ~IRQ_WORK_PENDING;
<------>(void)atomic_cmpxchg(&work->flags, flags, flags & ~IRQ_WORK_BUSY);
}
 
static void irq_work_run_list(struct llist_head *list)
{
<------>struct irq_work *work, *tmp;
<------>struct llist_node *llnode;
 
<------>BUG_ON(!irqs_disabled());
 
<------>if (llist_empty(list))
<------><------>return;
 
<------>llnode = llist_del_all(list);
<------>llist_for_each_entry_safe(work, tmp, llnode, llnode)
<------><------>irq_work_single(work);
}
 
/*
 * hotplug calls this through:
 *  hotplug_cfd() -> flush_smp_call_function_queue()
 */
void irq_work_run(void)
{
<------>irq_work_run_list(this_cpu_ptr(&raised_list));
<------>irq_work_run_list(this_cpu_ptr(&lazy_list));
}
EXPORT_SYMBOL_GPL(irq_work_run);
 
void irq_work_tick(void)
{
<------>struct llist_head *raised = this_cpu_ptr(&raised_list);
 
<------>if (!llist_empty(raised) && !arch_irq_work_has_interrupt())
<------><------>irq_work_run_list(raised);
<------>irq_work_run_list(this_cpu_ptr(&lazy_list));
}
 
/*
 * Synchronize against the irq_work @entry, ensures the entry is not
 * currently in use.
 */
void irq_work_sync(struct irq_work *work)
{
<------>lockdep_assert_irqs_enabled();
 
<------>while (atomic_read(&work->flags) & IRQ_WORK_BUSY)
<------><------>cpu_relax();
}
EXPORT_SYMBOL_GPL(irq_work_sync);