LXR linux/block/blk-mq-pci.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Copyright (c) 2016 Christoph Hellwig.
   4 */
   5#include <linux/kobject.h>
   6#include <linux/blkdev.h>
   7#include <linux/blk-mq.h>
   8#include <linux/blk-mq-pci.h>
   9#include <linux/pci.h>
  10#include <linux/module.h>
  11
  12#include "blk-mq.h"
  13
  14/**
  15 * blk_mq_pci_map_queues - provide a default queue mapping for PCI device
  16 * @qmap:       CPU to hardware queue map.
  17 * @pdev:       PCI device associated with @set.
  18 * @offset:     Offset to use for the pci irq vector
  19 *
  20 * This function assumes the PCI device @pdev has at least as many available
  21 * interrupt vectors as @set has queues.  It will then query the vector
  22 * corresponding to each queue for it's affinity mask and built queue mapping
  23 * that maps a queue to the CPUs that have irq affinity for the corresponding
  24 * vector.
  25 */
  26int blk_mq_pci_map_queues(struct blk_mq_queue_map *qmap, struct pci_dev *pdev,
  27                            int offset)
  28{
  29        const struct cpumask *mask;
  30        unsigned int queue, cpu;
  31
  32        for (queue = 0; queue < qmap->nr_queues; queue++) {
  33                mask = pci_irq_get_affinity(pdev, queue + offset);
  34                if (!mask)
  35                        goto fallback;
  36
  37                for_each_cpu(cpu, mask)
  38                        qmap->mq_map[cpu] = qmap->queue_offset + queue;
  39        }
  40
  41        return 0;
  42
  43fallback:
  44        WARN_ON_ONCE(qmap->nr_queues > 1);
  45        blk_mq_clear_mq_map(qmap);
  46        return 0;
  47}
  48EXPORT_SYMBOL_GPL(blk_mq_pci_map_queues);
  49