1/* 2 * Functions related to softirq rq completions 3 */ 4#include <linux/kernel.h> 5#include <linux/module.h> 6#include <linux/init.h> 7#include <linux/bio.h> 8#include <linux/blkdev.h> 9#include <linux/interrupt.h> 10#include <linux/cpu.h> 11 12#include "blk.h" 13 14static DEFINE_PER_CPU(struct list_head, blk_cpu_done); 15 16/* 17 * Softirq action handler - move entries to local list and loop over them 18 * while passing them to the queue registered handler. 19 */ 20static void blk_done_softirq(struct softirq_action *h) 21{ 22 struct list_head *cpu_list, local_list; 23 24 local_irq_disable(); 25 cpu_list = &__get_cpu_var(blk_cpu_done); 26 list_replace_init(cpu_list, &local_list); 27 local_irq_enable(); 28 29 while (!list_empty(&local_list)) { 30 struct request *rq; 31 32 rq = list_entry(local_list.next, struct request, csd.list); 33 list_del_init(&rq->csd.list); 34 rq->q->softirq_done_fn(rq); 35 } 36} 37 38#if defined(CONFIG_SMP) && defined(CONFIG_USE_GENERIC_SMP_HELPERS) 39static void trigger_softirq(void *data) 40{ 41 struct request *rq = data; 42 unsigned long flags; 43 struct list_head *list; 44 45 local_irq_save(flags); 46 list = &__get_cpu_var(blk_cpu_done); 47 list_add_tail(&rq->csd.list, list); 48 49 if (list->next == &rq->csd.list) 50 raise_softirq_irqoff(BLOCK_SOFTIRQ); 51 52 local_irq_restore(flags); 53} 54 55/* 56 * Setup and invoke a run of 'trigger_softirq' on the given cpu. 57 */ 58static int raise_blk_irq(int cpu, struct request *rq) 59{ 60 if (cpu_online(cpu)) { 61 struct call_single_data *data = &rq->csd; 62 63 data->func = trigger_softirq; 64 data->info = rq; 65 data->flags = 0; 66 67 __smp_call_function_single(cpu, data, 0); 68 return 0; 69 } 70 71 return 1; 72} 73#else /* CONFIG_SMP && CONFIG_USE_GENERIC_SMP_HELPERS */ 74static int raise_blk_irq(int cpu, struct request *rq) 75{ 76 return 1; 77} 78#endif 79 80static int __cpuinit blk_cpu_notify(struct notifier_block *self, 81 unsigned long action, void *hcpu) 82{ 83 /* 84 * If a CPU goes away, splice its entries to the current CPU 85 * and trigger a run of the softirq 86 */ 87 if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) { 88 int cpu = (unsigned long) hcpu; 89 90 local_irq_disable(); 91 list_splice_init(&per_cpu(blk_cpu_done, cpu), 92 &__get_cpu_var(blk_cpu_done)); 93 raise_softirq_irqoff(BLOCK_SOFTIRQ); 94 local_irq_enable(); 95 } 96 97 return NOTIFY_OK; 98} 99 100static struct notifier_block __cpuinitdata blk_cpu_notifier = { 101 .notifier_call = blk_cpu_notify, 102}; 103 104void __blk_complete_request(struct request *req) 105{ 106 struct request_queue *q = req->q; 107 unsigned long flags; 108 int ccpu, cpu, group_cpu; 109 110 BUG_ON(!q->softirq_done_fn); 111 112 local_irq_save(flags); 113 cpu = smp_processor_id(); 114 group_cpu = blk_cpu_to_group(cpu); 115 116 /* 117 * Select completion CPU 118 */ 119 if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags) && req->cpu != -1) 120 ccpu = req->cpu; 121 else 122 ccpu = cpu; 123 124 if (ccpu == cpu || ccpu == group_cpu) { 125 struct list_head *list; 126do_local: 127 list = &__get_cpu_var(blk_cpu_done); 128 list_add_tail(&req->csd.list, list); 129 130 /* 131 * if the list only contains our just added request, 132 * signal a raise of the softirq. If there are already 133 * entries there, someone already raised the irq but it 134 * hasn't run yet. 135 */ 136 if (list->next == &req->csd.list) 137 raise_softirq_irqoff(BLOCK_SOFTIRQ); 138 } else if (raise_blk_irq(ccpu, req)) 139 goto do_local; 140 141 local_irq_restore(flags); 142} 143 144/** 145 * blk_complete_request - end I/O on a request 146 * @req: the request being processed 147 * 148 * Description: 149 * Ends all I/O on a request. It does not handle partial completions, 150 * unless the driver actually implements this in its completion callback 151 * through requeueing. The actual completion happens out-of-order, 152 * through a softirq handler. The user must have registered a completion 153 * callback through blk_queue_softirq_done(). 154 **/ 155void blk_complete_request(struct request *req) 156{ 157 if (unlikely(blk_should_fake_timeout(req->q))) 158 return; 159 if (!blk_mark_rq_complete(req)) 160 __blk_complete_request(req); 161} 162EXPORT_SYMBOL(blk_complete_request); 163 164static __init int blk_softirq_init(void) 165{ 166 int i; 167 168 for_each_possible_cpu(i) 169 INIT_LIST_HEAD(&per_cpu(blk_cpu_done, i)); 170 171 open_softirq(BLOCK_SOFTIRQ, blk_done_softirq); 172 register_hotcpu_notifier(&blk_cpu_notifier); 173 return 0; 174} 175subsys_initcall(blk_softirq_init); 176