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); 56