block/blk-mq-pci.c

   1 /*
   2  * Copyright (c) 2016 Christoph Hellwig.
   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/kobject.h>
  14 #include <linux/blkdev.h>
  15 #include <linux/blk-mq.h>
  16 #include <linux/blk-mq-pci.h>
  17 #include <linux/pci.h>
  18 #include <linux/module.h>
  19
  20 /**
  21  * blk_mq_pci_map_queues - provide a default queue mapping for PCI device
  22  * @set:        tagset to provide the mapping for
  23  * @pdev:       PCI device associated with @set.
  24  * @offset:     Offset to use for the pci irq vector
  25  *
  26  * This function assumes the PCI device @pdev has at least as many available
  27  * interrupt vectors as @set has queues.  It will then query the vector
  28  * corresponding to each queue for it's affinity mask and built queue mapping
  29  * that maps a queue to the CPUs that have irq affinity for the corresponding
  30  * vector.
  31  */
  32 int blk_mq_pci_map_queues(struct blk_mq_tag_set *set, struct pci_dev *pdev,
  33                             int offset)
  34 {
  35         const struct cpumask *mask;
  36         unsigned int queue, cpu;
  37
  38         for (queue = 0; queue < set->nr_hw_queues; queue++) {
  39                 mask = pci_irq_get_affinity(pdev, queue + offset);
  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
  49 fallback:
  50         WARN_ON_ONCE(set->nr_hw_queues > 1);
  51         for_each_possible_cpu(cpu)
  52                 set->mq_map[cpu] = 0;
  53         return 0;
  54 }
  55 EXPORT_SYMBOL_GPL(blk_mq_pci_map_queues);