Commit | Line | Data |
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b646fc59 JA |
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> | |
39be3501 | 11 | #include <linux/sched.h> |
b646fc59 JA |
12 | |
13 | #include "blk.h" | |
14 | ||
15 | static DEFINE_PER_CPU(struct list_head, blk_cpu_done); | |
16 | ||
c7c22e4d JA |
17 | /* |
18 | * Softirq action handler - move entries to local list and loop over them | |
19 | * while passing them to the queue registered handler. | |
20 | */ | |
21 | static void blk_done_softirq(struct softirq_action *h) | |
22 | { | |
23 | struct list_head *cpu_list, local_list; | |
24 | ||
25 | local_irq_disable(); | |
170d800a | 26 | cpu_list = this_cpu_ptr(&blk_cpu_done); |
c7c22e4d JA |
27 | list_replace_init(cpu_list, &local_list); |
28 | local_irq_enable(); | |
29 | ||
30 | while (!list_empty(&local_list)) { | |
31 | struct request *rq; | |
32 | ||
360f92c2 JA |
33 | rq = list_entry(local_list.next, struct request, ipi_list); |
34 | list_del_init(&rq->ipi_list); | |
c7c22e4d JA |
35 | rq->q->softirq_done_fn(rq); |
36 | } | |
37 | } | |
38 | ||
0a06ff06 | 39 | #ifdef CONFIG_SMP |
c7c22e4d JA |
40 | static 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); | |
170d800a | 47 | list = this_cpu_ptr(&blk_cpu_done); |
360f92c2 | 48 | list_add_tail(&rq->ipi_list, list); |
c7c22e4d | 49 | |
360f92c2 | 50 | if (list->next == &rq->ipi_list) |
c7c22e4d JA |
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 | */ | |
59 | static 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 | ||
c46fff2a | 68 | smp_call_function_single_async(cpu, data); |
c7c22e4d JA |
69 | return 0; |
70 | } | |
71 | ||
72 | return 1; | |
73 | } | |
0a06ff06 | 74 | #else /* CONFIG_SMP */ |
c7c22e4d JA |
75 | static int raise_blk_irq(int cpu, struct request *rq) |
76 | { | |
77 | return 1; | |
78 | } | |
79 | #endif | |
80 | ||
9a659f43 | 81 | static int blk_softirq_cpu_dead(unsigned int cpu) |
b646fc59 JA |
82 | { |
83 | /* | |
84 | * If a CPU goes away, splice its entries to the current CPU | |
85 | * and trigger a run of the softirq | |
86 | */ | |
9a659f43 SAS |
87 | local_irq_disable(); |
88 | list_splice_init(&per_cpu(blk_cpu_done, cpu), | |
89 | this_cpu_ptr(&blk_cpu_done)); | |
90 | raise_softirq_irqoff(BLOCK_SOFTIRQ); | |
91 | local_irq_enable(); | |
b646fc59 | 92 | |
9a659f43 | 93 | return 0; |
b646fc59 JA |
94 | } |
95 | ||
242f9dcb | 96 | void __blk_complete_request(struct request *req) |
b646fc59 | 97 | { |
39be3501 | 98 | int ccpu, cpu; |
c7c22e4d | 99 | struct request_queue *q = req->q; |
b646fc59 | 100 | unsigned long flags; |
39be3501 | 101 | bool shared = false; |
b646fc59 | 102 | |
c7c22e4d | 103 | BUG_ON(!q->softirq_done_fn); |
b646fc59 JA |
104 | |
105 | local_irq_save(flags); | |
c7c22e4d | 106 | cpu = smp_processor_id(); |
b646fc59 | 107 | |
c7c22e4d JA |
108 | /* |
109 | * Select completion CPU | |
110 | */ | |
8ad6a56f | 111 | if (req->cpu != -1) { |
c7c22e4d | 112 | ccpu = req->cpu; |
39be3501 PZ |
113 | if (!test_bit(QUEUE_FLAG_SAME_FORCE, &q->queue_flags)) |
114 | shared = cpus_share_cache(cpu, ccpu); | |
5757a6d7 | 115 | } else |
c7c22e4d JA |
116 | ccpu = cpu; |
117 | ||
bcf30e75 | 118 | /* |
39be3501 PZ |
119 | * If current CPU and requested CPU share a cache, run the softirq on |
120 | * the current CPU. One might concern this is just like | |
bcf30e75 SL |
121 | * QUEUE_FLAG_SAME_FORCE, but actually not. blk_complete_request() is |
122 | * running in interrupt handler, and currently I/O controller doesn't | |
123 | * support multiple interrupts, so current CPU is unique actually. This | |
124 | * avoids IPI sending from current CPU to the first CPU of a group. | |
125 | */ | |
39be3501 | 126 | if (ccpu == cpu || shared) { |
c7c22e4d JA |
127 | struct list_head *list; |
128 | do_local: | |
170d800a | 129 | list = this_cpu_ptr(&blk_cpu_done); |
360f92c2 | 130 | list_add_tail(&req->ipi_list, list); |
c7c22e4d JA |
131 | |
132 | /* | |
133 | * if the list only contains our just added request, | |
134 | * signal a raise of the softirq. If there are already | |
135 | * entries there, someone already raised the irq but it | |
136 | * hasn't run yet. | |
137 | */ | |
360f92c2 | 138 | if (list->next == &req->ipi_list) |
c7c22e4d JA |
139 | raise_softirq_irqoff(BLOCK_SOFTIRQ); |
140 | } else if (raise_blk_irq(ccpu, req)) | |
141 | goto do_local; | |
b646fc59 JA |
142 | |
143 | local_irq_restore(flags); | |
144 | } | |
242f9dcb JA |
145 | |
146 | /** | |
147 | * blk_complete_request - end I/O on a request | |
148 | * @req: the request being processed | |
149 | * | |
150 | * Description: | |
151 | * Ends all I/O on a request. It does not handle partial completions, | |
152 | * unless the driver actually implements this in its completion callback | |
153 | * through requeueing. The actual completion happens out-of-order, | |
154 | * through a softirq handler. The user must have registered a completion | |
155 | * callback through blk_queue_softirq_done(). | |
156 | **/ | |
157 | void blk_complete_request(struct request *req) | |
158 | { | |
581d4e28 JA |
159 | if (unlikely(blk_should_fake_timeout(req->q))) |
160 | return; | |
242f9dcb JA |
161 | if (!blk_mark_rq_complete(req)) |
162 | __blk_complete_request(req); | |
163 | } | |
b646fc59 JA |
164 | EXPORT_SYMBOL(blk_complete_request); |
165 | ||
3c18ce71 | 166 | static __init int blk_softirq_init(void) |
b646fc59 JA |
167 | { |
168 | int i; | |
169 | ||
170 | for_each_possible_cpu(i) | |
171 | INIT_LIST_HEAD(&per_cpu(blk_cpu_done, i)); | |
172 | ||
173 | open_softirq(BLOCK_SOFTIRQ, blk_done_softirq); | |
9a659f43 SAS |
174 | cpuhp_setup_state_nocalls(CPUHP_BLOCK_SOFTIRQ_DEAD, |
175 | "block/softirq:dead", NULL, | |
176 | blk_softirq_cpu_dead); | |
b646fc59 JA |
177 | return 0; |
178 | } | |
179 | subsys_initcall(blk_softirq_init); |