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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 | ||
14 | static DEFINE_PER_CPU(struct list_head, blk_cpu_done); | |
15 | ||
16 | static int __cpuinit blk_cpu_notify(struct notifier_block *self, | |
17 | unsigned long action, void *hcpu) | |
18 | { | |
19 | /* | |
20 | * If a CPU goes away, splice its entries to the current CPU | |
21 | * and trigger a run of the softirq | |
22 | */ | |
23 | if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) { | |
24 | int cpu = (unsigned long) hcpu; | |
25 | ||
26 | local_irq_disable(); | |
27 | list_splice_init(&per_cpu(blk_cpu_done, cpu), | |
28 | &__get_cpu_var(blk_cpu_done)); | |
29 | raise_softirq_irqoff(BLOCK_SOFTIRQ); | |
30 | local_irq_enable(); | |
31 | } | |
32 | ||
33 | return NOTIFY_OK; | |
34 | } | |
35 | ||
36 | ||
37 | static struct notifier_block blk_cpu_notifier __cpuinitdata = { | |
38 | .notifier_call = blk_cpu_notify, | |
39 | }; | |
40 | ||
41 | /* | |
42 | * splice the completion data to a local structure and hand off to | |
43 | * process_completion_queue() to complete the requests | |
44 | */ | |
45 | static void blk_done_softirq(struct softirq_action *h) | |
46 | { | |
47 | struct list_head *cpu_list, local_list; | |
48 | ||
49 | local_irq_disable(); | |
50 | cpu_list = &__get_cpu_var(blk_cpu_done); | |
51 | list_replace_init(cpu_list, &local_list); | |
52 | local_irq_enable(); | |
53 | ||
54 | while (!list_empty(&local_list)) { | |
55 | struct request *rq; | |
56 | ||
57 | rq = list_entry(local_list.next, struct request, donelist); | |
58 | list_del_init(&rq->donelist); | |
59 | rq->q->softirq_done_fn(rq); | |
60 | } | |
61 | } | |
62 | ||
63 | /** | |
64 | * blk_complete_request - end I/O on a request | |
65 | * @req: the request being processed | |
66 | * | |
67 | * Description: | |
68 | * Ends all I/O on a request. It does not handle partial completions, | |
69 | * unless the driver actually implements this in its completion callback | |
70 | * through requeueing. The actual completion happens out-of-order, | |
71 | * through a softirq handler. The user must have registered a completion | |
72 | * callback through blk_queue_softirq_done(). | |
73 | **/ | |
74 | ||
75 | void blk_complete_request(struct request *req) | |
76 | { | |
77 | struct list_head *cpu_list; | |
78 | unsigned long flags; | |
79 | ||
80 | BUG_ON(!req->q->softirq_done_fn); | |
81 | ||
82 | local_irq_save(flags); | |
83 | ||
84 | cpu_list = &__get_cpu_var(blk_cpu_done); | |
85 | list_add_tail(&req->donelist, cpu_list); | |
86 | raise_softirq_irqoff(BLOCK_SOFTIRQ); | |
87 | ||
88 | local_irq_restore(flags); | |
89 | } | |
90 | EXPORT_SYMBOL(blk_complete_request); | |
91 | ||
92 | int __init blk_softirq_init(void) | |
93 | { | |
94 | int i; | |
95 | ||
96 | for_each_possible_cpu(i) | |
97 | INIT_LIST_HEAD(&per_cpu(blk_cpu_done, i)); | |
98 | ||
99 | open_softirq(BLOCK_SOFTIRQ, blk_done_softirq); | |
100 | register_hotcpu_notifier(&blk_cpu_notifier); | |
101 | return 0; | |
102 | } | |
103 | subsys_initcall(blk_softirq_init); |