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

   1/*
   2 * Copyright (c) 2017 Sagi Grimberg.
   3 *
   4 * This program is free software; you can redistribute it and/or modify it
   5 * under the terms and conditions of the GNU General Public License,
   6 * version 2, as published by the Free Software Foundation.
   7 *
   8 * This program is distributed in the hope it will be useful, but WITHOUT
   9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  11 * more details.
  12 */
  13#include <linux/blk-mq.h>
  14#include <linux/blk-mq-rdma.h>
  15#include <rdma/ib_verbs.h>
  16
  17/**
  18 * blk_mq_rdma_map_queues - provide a default queue mapping for rdma device
  19 * @set:        tagset to provide the mapping for
  20 * @dev:        rdma device associated with @set.
  21 * @first_vec:  first interrupt vectors to use for queues (usually 0)
  22 *
  23 * This function assumes the rdma device @dev has at least as many available
  24 * interrupt vetors as @set has queues.  It will then query it's affinity mask
  25 * and built queue mapping that maps a queue to the CPUs that have irq affinity
  26 * for the corresponding vector.
  27 *
  28 * In case either the driver passed a @dev with less vectors than
  29 * @set->nr_hw_queues, or @dev does not provide an affinity mask for a
  30 * vector, we fallback to the naive mapping.
  31 */
  32int blk_mq_rdma_map_queues(struct blk_mq_tag_set *set,
  33                struct ib_device *dev, int first_vec)
  34{
  35        const struct cpumask *mask;
  36        unsigned int queue, cpu;
  37
  38        for (queue = 0; queue < set->nr_hw_queues; queue++) {
  39                mask = ib_get_vector_affinity(dev, first_vec + queue);
  40                if (!mask)
  41                        goto fallback;
  42
  43                for_each_cpu(cpu, mask)
  44                        set->mq_map[cpu] = queue;
  45        }
  46
  47        return 0;
  48
  49fallback:
  50        return blk_mq_map_queues(set);
  51}
  52EXPORT_SYMBOL_GPL(blk_mq_rdma_map_queues);
  53