the-tree/block/blk-mq-rdma.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  * Copyright (c) 2017 Sagi Grimberg.
0004  */
0005 #include <linux/blk-mq.h>
0006 #include <linux/blk-mq-rdma.h>
0007 #include <rdma/ib_verbs.h>
0008
0009 /**
0010  * blk_mq_rdma_map_queues - provide a default queue mapping for rdma device
0011  * @map:    CPU to hardware queue map.
0012  * @dev:    rdma device to provide a mapping for.
0013  * @first_vec:  first interrupt vectors to use for queues (usually 0)
0014  *
0015  * This function assumes the rdma device @dev has at least as many available
0016  * interrupt vetors as @set has queues.  It will then query it's affinity mask
0017  * and built queue mapping that maps a queue to the CPUs that have irq affinity
0018  * for the corresponding vector.
0019  *
0020  * In case either the driver passed a @dev with less vectors than
0021  * @set->nr_hw_queues, or @dev does not provide an affinity mask for a
0022  * vector, we fallback to the naive mapping.
0023  */
0024 int blk_mq_rdma_map_queues(struct blk_mq_queue_map *map,
0025         struct ib_device *dev, int first_vec)
0026 {
0027     const struct cpumask *mask;
0028     unsigned int queue, cpu;
0029
0030     for (queue = 0; queue < map->nr_queues; queue++) {
0031         mask = ib_get_vector_affinity(dev, first_vec + queue);
0032         if (!mask)
0033             goto fallback;
0034
0035         for_each_cpu(cpu, mask)
0036             map->mq_map[cpu] = map->queue_offset + queue;
0037     }
0038
0039     return 0;
0040
0041 fallback:
0042     return blk_mq_map_queues(map);
0043 }
0044 EXPORT_SYMBOL_GPL(blk_mq_rdma_map_queues);