blob: ec9e60636f4335c8e6af0617f9fbc61335c9fea5 [file] [log] [blame]
Jens Axboeb646fc52008-07-28 13:06:00 +02001/*
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>
Peter Zijlstra39be3502012-01-26 12:44:34 +010011#include <linux/sched.h>
Jens Axboeb646fc52008-07-28 13:06:00 +020012
13#include "blk.h"
14
15static DEFINE_PER_CPU(struct list_head, blk_cpu_done);
16
Jens Axboec7c22e42008-09-13 20:26:01 +020017/*
18 * Softirq action handler - move entries to local list and loop over them
19 * while passing them to the queue registered handler.
20 */
21static void blk_done_softirq(struct softirq_action *h)
22{
23 struct list_head *cpu_list, local_list;
24
25 local_irq_disable();
26 cpu_list = &__get_cpu_var(blk_cpu_done);
27 list_replace_init(cpu_list, &local_list);
28 local_irq_enable();
29
30 while (!list_empty(&local_list)) {
31 struct request *rq;
32
33 rq = list_entry(local_list.next, struct request, csd.list);
34 list_del_init(&rq->csd.list);
35 rq->q->softirq_done_fn(rq);
36 }
37}
38
39#if defined(CONFIG_SMP) && defined(CONFIG_USE_GENERIC_SMP_HELPERS)
40static void trigger_softirq(void *data)
41{
42 struct request *rq = data;
43 unsigned long flags;
44 struct list_head *list;
45
46 local_irq_save(flags);
47 list = &__get_cpu_var(blk_cpu_done);
48 list_add_tail(&rq->csd.list, list);
49
50 if (list->next == &rq->csd.list)
51 raise_softirq_irqoff(BLOCK_SOFTIRQ);
52
53 local_irq_restore(flags);
54}
55
56/*
57 * Setup and invoke a run of 'trigger_softirq' on the given cpu.
58 */
59static int raise_blk_irq(int cpu, struct request *rq)
60{
61 if (cpu_online(cpu)) {
62 struct call_single_data *data = &rq->csd;
63
64 data->func = trigger_softirq;
65 data->info = rq;
66 data->flags = 0;
67
Peter Zijlstra6e275632009-02-25 13:59:48 +010068 __smp_call_function_single(cpu, data, 0);
Jens Axboec7c22e42008-09-13 20:26:01 +020069 return 0;
70 }
71
72 return 1;
73}
74#else /* CONFIG_SMP && CONFIG_USE_GENERIC_SMP_HELPERS */
75static int raise_blk_irq(int cpu, struct request *rq)
76{
77 return 1;
78}
79#endif
80
Paul Gortmaker0b776b02013-06-19 15:26:23 -040081static int blk_cpu_notify(struct notifier_block *self, unsigned long action,
82 void *hcpu)
Jens Axboeb646fc52008-07-28 13:06:00 +020083{
84 /*
85 * If a CPU goes away, splice its entries to the current CPU
86 * and trigger a run of the softirq
87 */
88 if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) {
89 int cpu = (unsigned long) hcpu;
90
91 local_irq_disable();
92 list_splice_init(&per_cpu(blk_cpu_done, cpu),
93 &__get_cpu_var(blk_cpu_done));
94 raise_softirq_irqoff(BLOCK_SOFTIRQ);
95 local_irq_enable();
96 }
97
98 return NOTIFY_OK;
99}
100
Paul Gortmaker0b776b02013-06-19 15:26:23 -0400101static struct notifier_block blk_cpu_notifier = {
Jens Axboeb646fc52008-07-28 13:06:00 +0200102 .notifier_call = blk_cpu_notify,
103};
104
Jens Axboe242f9dc2008-09-14 05:55:09 -0700105void __blk_complete_request(struct request *req)
Jens Axboeb646fc52008-07-28 13:06:00 +0200106{
Peter Zijlstra39be3502012-01-26 12:44:34 +0100107 int ccpu, cpu;
Jens Axboec7c22e42008-09-13 20:26:01 +0200108 struct request_queue *q = req->q;
Jens Axboeb646fc52008-07-28 13:06:00 +0200109 unsigned long flags;
Peter Zijlstra39be3502012-01-26 12:44:34 +0100110 bool shared = false;
Jens Axboeb646fc52008-07-28 13:06:00 +0200111
Jens Axboec7c22e42008-09-13 20:26:01 +0200112 BUG_ON(!q->softirq_done_fn);
Jens Axboeb646fc52008-07-28 13:06:00 +0200113
114 local_irq_save(flags);
Jens Axboec7c22e42008-09-13 20:26:01 +0200115 cpu = smp_processor_id();
Jens Axboeb646fc52008-07-28 13:06:00 +0200116
Jens Axboec7c22e42008-09-13 20:26:01 +0200117 /*
118 * Select completion CPU
119 */
Tao Ma8ad6a562011-09-14 09:31:01 +0200120 if (req->cpu != -1) {
Jens Axboec7c22e42008-09-13 20:26:01 +0200121 ccpu = req->cpu;
Peter Zijlstra39be3502012-01-26 12:44:34 +0100122 if (!test_bit(QUEUE_FLAG_SAME_FORCE, &q->queue_flags))
123 shared = cpus_share_cache(cpu, ccpu);
Dan Williams5757a6d2011-07-23 20:44:25 +0200124 } else
Jens Axboec7c22e42008-09-13 20:26:01 +0200125 ccpu = cpu;
126
Shaohua Libcf30e72011-08-11 10:39:04 +0200127 /*
Peter Zijlstra39be3502012-01-26 12:44:34 +0100128 * If current CPU and requested CPU share a cache, run the softirq on
129 * the current CPU. One might concern this is just like
Shaohua Libcf30e72011-08-11 10:39:04 +0200130 * QUEUE_FLAG_SAME_FORCE, but actually not. blk_complete_request() is
131 * running in interrupt handler, and currently I/O controller doesn't
132 * support multiple interrupts, so current CPU is unique actually. This
133 * avoids IPI sending from current CPU to the first CPU of a group.
134 */
Peter Zijlstra39be3502012-01-26 12:44:34 +0100135 if (ccpu == cpu || shared) {
Jens Axboec7c22e42008-09-13 20:26:01 +0200136 struct list_head *list;
137do_local:
138 list = &__get_cpu_var(blk_cpu_done);
139 list_add_tail(&req->csd.list, list);
140
141 /*
142 * if the list only contains our just added request,
143 * signal a raise of the softirq. If there are already
144 * entries there, someone already raised the irq but it
145 * hasn't run yet.
146 */
147 if (list->next == &req->csd.list)
148 raise_softirq_irqoff(BLOCK_SOFTIRQ);
149 } else if (raise_blk_irq(ccpu, req))
150 goto do_local;
Jens Axboeb646fc52008-07-28 13:06:00 +0200151
152 local_irq_restore(flags);
153}
Jens Axboe242f9dc2008-09-14 05:55:09 -0700154
155/**
156 * blk_complete_request - end I/O on a request
157 * @req: the request being processed
158 *
159 * Description:
160 * Ends all I/O on a request. It does not handle partial completions,
161 * unless the driver actually implements this in its completion callback
162 * through requeueing. The actual completion happens out-of-order,
163 * through a softirq handler. The user must have registered a completion
164 * callback through blk_queue_softirq_done().
165 **/
166void blk_complete_request(struct request *req)
167{
Jens Axboe581d4e22008-09-14 05:56:33 -0700168 if (unlikely(blk_should_fake_timeout(req->q)))
169 return;
Jens Axboe242f9dc2008-09-14 05:55:09 -0700170 if (!blk_mark_rq_complete(req))
171 __blk_complete_request(req);
172}
Jens Axboeb646fc52008-07-28 13:06:00 +0200173EXPORT_SYMBOL(blk_complete_request);
174
Roel Kluin3c18ce72008-12-10 15:47:33 +0100175static __init int blk_softirq_init(void)
Jens Axboeb646fc52008-07-28 13:06:00 +0200176{
177 int i;
178
179 for_each_possible_cpu(i)
180 INIT_LIST_HEAD(&per_cpu(blk_cpu_done, i));
181
182 open_softirq(BLOCK_SOFTIRQ, blk_done_softirq);
183 register_hotcpu_notifier(&blk_cpu_notifier);
184 return 0;
185}
186subsys_initcall(blk_softirq_init);