linux/lib/cpu_rmap.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * cpu_rmap.c: CPU affinity reverse-map support
 * Copyright 2011 Solarflare Communications Inc.
 */

#include <linux/cpu_rmap.h>
#include <linux/interrupt.h>
#include <linux/export.h>

/*
 * These functions maintain a mapping from CPUs to some ordered set of
 * objects with CPU affinities.  This can be seen as a reverse-map of
 * CPU affinity.  However, we do not assume that the object affinities
 * cover all CPUs in the system.  For those CPUs not directly covered
 * by object affinities, we attempt to find a nearest object based on
 * CPU topology.
 */

/**
 * alloc_cpu_rmap - allocate CPU affinity reverse-map
 * @size: Number of objects to be mapped
 * @flags: Allocation flags e.g. %GFP_KERNEL
 */
struct cpu_rmap *alloc_cpu_rmap(unsigned int size, gfp_t flags)
{ … }
EXPORT_SYMBOL(…);

/**
 * cpu_rmap_release - internal reclaiming helper called from kref_put
 * @ref: kref to struct cpu_rmap
 */
static void cpu_rmap_release(struct kref *ref)
{ … }

/**
 * cpu_rmap_get - internal helper to get new ref on a cpu_rmap
 * @rmap: reverse-map allocated with alloc_cpu_rmap()
 */
static inline void cpu_rmap_get(struct cpu_rmap *rmap)
{ … }

/**
 * cpu_rmap_put - release ref on a cpu_rmap
 * @rmap: reverse-map allocated with alloc_cpu_rmap()
 */
int cpu_rmap_put(struct cpu_rmap *rmap)
{ … }
EXPORT_SYMBOL(…);

/* Reevaluate nearest object for given CPU, comparing with the given
 * neighbours at the given distance.
 */
static bool cpu_rmap_copy_neigh(struct cpu_rmap *rmap, unsigned int cpu,
				const struct cpumask *mask, u16 dist)
{ … }

#ifdef DEBUG
static void debug_print_rmap(const struct cpu_rmap *rmap, const char *prefix)
{
	unsigned index;
	unsigned int cpu;

	pr_info("cpu_rmap %p, %s:\n", rmap, prefix);

	for_each_possible_cpu(cpu) {
		index = rmap->near[cpu].index;
		pr_info("cpu %d -> obj %u (distance %u)\n",
			cpu, index, rmap->near[cpu].dist);
	}
}
#else
static inline void
debug_print_rmap(const struct cpu_rmap *rmap, const char *prefix)
{ … }
#endif

static int get_free_index(struct cpu_rmap *rmap)
{ … }

/**
 * cpu_rmap_add - add object to a rmap
 * @rmap: CPU rmap allocated with alloc_cpu_rmap()
 * @obj: Object to add to rmap
 *
 * Return index of object or -ENOSPC if no free entry was found
 */
int cpu_rmap_add(struct cpu_rmap *rmap, void *obj)
{ … }
EXPORT_SYMBOL(…);

/**
 * cpu_rmap_update - update CPU rmap following a change of object affinity
 * @rmap: CPU rmap to update
 * @index: Index of object whose affinity changed
 * @affinity: New CPU affinity of object
 */
int cpu_rmap_update(struct cpu_rmap *rmap, u16 index,
		    const struct cpumask *affinity)
{ … }
EXPORT_SYMBOL(…);

/* Glue between IRQ affinity notifiers and CPU rmaps */

struct irq_glue { … };

/**
 * free_irq_cpu_rmap - free a CPU affinity reverse-map used for IRQs
 * @rmap: Reverse-map allocated with alloc_irq_cpu_map(), or %NULL
 *
 * Must be called in process context, before freeing the IRQs.
 */
void free_irq_cpu_rmap(struct cpu_rmap *rmap)
{ … }
EXPORT_SYMBOL(…);

/**
 * irq_cpu_rmap_notify - callback for IRQ subsystem when IRQ affinity updated
 * @notify: struct irq_affinity_notify passed by irq/manage.c
 * @mask: cpu mask for new SMP affinity
 *
 * This is executed in workqueue context.
 */
static void
irq_cpu_rmap_notify(struct irq_affinity_notify *notify, const cpumask_t *mask)
{ … }

/**
 * irq_cpu_rmap_release - reclaiming callback for IRQ subsystem
 * @ref: kref to struct irq_affinity_notify passed by irq/manage.c
 */
static void irq_cpu_rmap_release(struct kref *ref)
{ … }

/**
 * irq_cpu_rmap_remove - remove an IRQ from a CPU affinity reverse-map
 * @rmap: The reverse-map
 * @irq: The IRQ number
 */
int irq_cpu_rmap_remove(struct cpu_rmap *rmap, int irq)
{ … }
EXPORT_SYMBOL(…);

/**
 * irq_cpu_rmap_add - add an IRQ to a CPU affinity reverse-map
 * @rmap: The reverse-map
 * @irq: The IRQ number
 *
 * This adds an IRQ affinity notifier that will update the reverse-map
 * automatically.
 *
 * Must be called in process context, after the IRQ is allocated but
 * before it is bound with request_irq().
 */
int irq_cpu_rmap_add(struct cpu_rmap *rmap, int irq)
{ … }
EXPORT_SYMBOL(…);