cregit-Linux how code gets into the kernel

Release 4.7 lib/cpu_rmap.c

Directory: lib
 * 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>
#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) { 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; }


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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); }


david decotignydavid decotigny31100.00%1100.00%

/** * 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); }


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/** * 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); }


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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; }


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#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); } }


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static inline void debug_print_rmap(const struct cpu_rmap *rmap, const char *prefix) { }


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#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; }


ben hutchingsben hutchings47100.00%1100.00%

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_sibling_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; }


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bartosz golaszewskibartosz golaszewski10.45%150.00%

EXPORT_SYMBOL(cpu_rmap_update); /* 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); }


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david decotignydavid decotigny11.52%150.00%

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 void irq_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); }


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/** * 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); }


ben hutchingsben hutchings3382.50%150.00%
david decotignydavid decotigny717.50%150.00%

/** * 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; }


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Overall Contributors

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Directory: lib
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