/* * cpu_rmap.c: CPU affinity reverse-map support * Copyright 2011 Solarflare Communications Inc. * * This program is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 as published * by the Free Software Foundation, incorporated herein by reference. */ #include <linux/cpu_rmap.h>#ifdef CONFIG_GENERIC_HARDIRQS#include <linux/interrupt.h>#endif#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){	struct cpu_rmap *rmap;	unsigned int cpu;	size_t obj_offset; 	/* This is a silly number of objects, and we use u16 indices. */	if (size > 0xffff)		return NULL; 	/* Offset of object pointer array from base structure */	obj_offset = ALIGN(offsetof(struct cpu_rmap, near[nr_cpu_ids]),			   sizeof(void *)); 	rmap = kzalloc(obj_offset + size * sizeof(rmap->obj[0]), flags);	if (!rmap)		return NULL; 	kref_init(&rmap->refcount);	rmap->obj = (void **)((char *)rmap + obj_offset); 	/* Initially assign CPUs to objects on a rota, since we have	 * no idea where the objects are.  Use infinite distance, so	 * any object with known distance is preferable.  Include the	 * CPUs that are not present/online, since we definitely want	 * any newly-hotplugged CPUs to have some object assigned.	 */	for_each_possible_cpu(cpu) {		rmap->near[cpu].index = cpu % size;		rmap->near[cpu].dist = CPU_RMAP_DIST_INF;	} 	rmap->size = size;	return rmap;}EXPORT_SYMBOL(alloc_cpu_rmap); /** * cpu_rmap_release - internal reclaiming helper called from kref_put * @ref: kref to struct cpu_rmap */static void cpu_rmap_release(struct kref *ref){	struct cpu_rmap *rmap = container_of(ref, struct cpu_rmap, refcount);	kfree(rmap);} /** * 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){	kref_get(&rmap->refcount);} /** * 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){	return kref_put(&rmap->refcount, cpu_rmap_release);}EXPORT_SYMBOL(cpu_rmap_put); /* 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){	int neigh; 	for_each_cpu(neigh, mask) {		if (rmap->near[cpu].dist > dist &&		    rmap->near[neigh].dist <= dist) {			rmap->near[cpu].index = rmap->near[neigh].index;			rmap->near[cpu].dist = dist;			return true;		}	}	return false;} #ifdef DEBUGstatic 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);	}}#elsestatic inline voiddebug_print_rmap(const struct cpu_rmap *rmap, const char *prefix){}#endif /** * 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. */int cpu_rmap_add(struct cpu_rmap *rmap, void *obj){	u16 index; 	BUG_ON(rmap->used >= rmap->size);	index = rmap->used++;	rmap->obj[index] = obj;	return index;}EXPORT_SYMBOL(cpu_rmap_add); /** * 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){	cpumask_var_t update_mask;	unsigned int cpu; 	if (unlikely(!zalloc_cpumask_var(&update_mask, GFP_KERNEL)))		return -ENOMEM; 	/* Invalidate distance for all CPUs for which this used to be	 * the nearest object.  Mark those CPUs for update.	 */	for_each_online_cpu(cpu) {		if (rmap->near[cpu].index == index) {			rmap->near[cpu].dist = CPU_RMAP_DIST_INF;			cpumask_set_cpu(cpu, update_mask);		}	} 	debug_print_rmap(rmap, "after invalidating old distances"); 	/* Set distance to 0 for all CPUs in the new affinity mask.	 * Mark all CPUs within their NUMA nodes for update.	 */	for_each_cpu(cpu, affinity) {		rmap->near[cpu].index = index;		rmap->near[cpu].dist = 0;		cpumask_or(update_mask, update_mask,			   cpumask_of_node(cpu_to_node(cpu)));	} 	debug_print_rmap(rmap, "after updating neighbours"); 	/* Update distances based on topology */	for_each_cpu(cpu, update_mask) {		if (cpu_rmap_copy_neigh(rmap, cpu,					topology_thread_cpumask(cpu), 1))			continue;		if (cpu_rmap_copy_neigh(rmap, cpu,					topology_core_cpumask(cpu), 2))			continue;		if (cpu_rmap_copy_neigh(rmap, cpu,					cpumask_of_node(cpu_to_node(cpu)), 3))			continue;		/* We could continue into NUMA node distances, but for now		 * we give up.		 */	} 	debug_print_rmap(rmap, "after copying neighbours"); 	free_cpumask_var(update_mask);	return 0;}EXPORT_SYMBOL(cpu_rmap_update); #ifdef CONFIG_GENERIC_HARDIRQS /* Glue between IRQ affinity notifiers and CPU rmaps */ struct irq_glue {	struct irq_affinity_notify notify;	struct cpu_rmap *rmap;	u16 index;}; /** * 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){	struct irq_glue *glue;	u16 index; 	if (!rmap)		return; 	for (index = 0; index < rmap->used; index++) {		glue = rmap->obj[index];		irq_set_affinity_notifier(glue->notify.irq, NULL);	} 	cpu_rmap_put(rmap);}EXPORT_SYMBOL(free_irq_cpu_rmap); /** * 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 voidirq_cpu_rmap_notify(struct irq_affinity_notify *notify, const cpumask_t *mask){	struct irq_glue *glue =		container_of(notify, struct irq_glue, notify);	int rc; 	rc = cpu_rmap_update(glue->rmap, glue->index, mask);	if (rc)		pr_warning("irq_cpu_rmap_notify: update failed: %d\n", rc);} /** * 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){	struct irq_glue *glue =		container_of(ref, struct irq_glue, notify.kref); 	cpu_rmap_put(glue->rmap);	kfree(glue);} /** * 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){	struct irq_glue *glue = kzalloc(sizeof(*glue), GFP_KERNEL);	int rc; 	if (!glue)		return -ENOMEM;	glue->notify.notify = irq_cpu_rmap_notify;	glue->notify.release = irq_cpu_rmap_release;	glue->rmap = rmap;	cpu_rmap_get(rmap);	glue->index = cpu_rmap_add(rmap, glue);	rc = irq_set_affinity_notifier(irq, &glue->notify);	if (rc) {		cpu_rmap_put(glue->rmap);		kfree(glue);	}	return rc;}EXPORT_SYMBOL(irq_cpu_rmap_add); #endif /* CONFIG_GENERIC_HARDIRQS */