block/blk-mq-rdma.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (c) 2017 Sagi Grimberg.
   4  */
   5 #include <linux/blk-mq.h>
   6 #include <linux/blk-mq-rdma.h>
   7 #include <rdma/ib_verbs.h>
   8
   9 /**
  10  * blk_mq_rdma_map_queues - provide a default queue mapping for rdma device
  11  * @map:        CPU to hardware queue map.
  12  * @dev:        rdma device to provide a mapping for.
  13  * @first_vec:  first interrupt vectors to use for queues (usually 0)
  14  *
  15  * This function assumes the rdma device @dev has at least as many available
  16  * interrupt vetors as @set has queues.  It will then query it's affinity mask
  17  * and built queue mapping that maps a queue to the CPUs that have irq affinity
  18  * for the corresponding vector.
  19  *
  20  * In case either the driver passed a @dev with less vectors than
  21  * @set->nr_hw_queues, or @dev does not provide an affinity mask for a
  22  * vector, we fallback to the naive mapping.
  23  */
  24 int blk_mq_rdma_map_queues(struct blk_mq_queue_map *map,
  25                 struct ib_device *dev, int first_vec)
  26 {
  27         const struct cpumask *mask;
  28         unsigned int queue, cpu;
  29
  30         for (queue = 0; queue < map->nr_queues; queue++) {
  31                 mask = ib_get_vector_affinity(dev, first_vec + queue);
  32                 if (!mask)
  33                         goto fallback;
  34
  35                 for_each_cpu(cpu, mask)
  36                         map->mq_map[cpu] = map->queue_offset + queue;
  37         }
  38
  39         return 0;
  40
  41 fallback:
  42         return blk_mq_map_queues(map);
  43 }
  44 EXPORT_SYMBOL_GPL(blk_mq_rdma_map_queues);