Jens Axboe | b646fc5 | 2008-07-28 13:06:00 +0200 | [diff] [blame] | 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); |