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  */
  32 int blk_mq_rdma_map_queues(struct blk_mq_queue_map *map,
  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 < map->nr_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                         map->mq_map[cpu] = map->queue_offset + queue;
  45         }
  46
  47         return 0;
  48
  49 fallback:
  50         return blk_mq_map_queues(map);
  51 }
  52 EXPORT_SYMBOL_GPL(blk_mq_rdma_map_queues);