| /* |
| * Functions related to softirq rq completions |
| */ |
| #include <linux/kernel.h> |
| #include <linux/module.h> |
| #include <linux/init.h> |
| #include <linux/bio.h> |
| #include <linux/blkdev.h> |
| #include <linux/interrupt.h> |
| #include <linux/cpu.h> |
| #include <linux/sched.h> |
| |
| #include "blk.h" |
| |
| static DEFINE_PER_CPU(struct list_head, blk_cpu_done); |
| |
| /* |
| * Softirq action handler - move entries to local list and loop over them |
| * while passing them to the queue registered handler. |
| */ |
| static void blk_done_softirq(struct softirq_action *h) |
| { |
| struct list_head *cpu_list, local_list; |
| |
| local_irq_disable(); |
| cpu_list = &__get_cpu_var(blk_cpu_done); |
| list_replace_init(cpu_list, &local_list); |
| local_irq_enable(); |
| |
| while (!list_empty(&local_list)) { |
| struct request *rq; |
| |
| rq = list_entry(local_list.next, struct request, csd.list); |
| list_del_init(&rq->csd.list); |
| rq->q->softirq_done_fn(rq); |
| } |
| } |
| |
| #ifdef CONFIG_SMP |
| static void trigger_softirq(void *data) |
| { |
| struct request *rq = data; |
| unsigned long flags; |
| struct list_head *list; |
| |
| local_irq_save(flags); |
| list = &__get_cpu_var(blk_cpu_done); |
| list_add_tail(&rq->csd.list, list); |
| |
| if (list->next == &rq->csd.list) |
| raise_softirq_irqoff(BLOCK_SOFTIRQ); |
| |
| local_irq_restore(flags); |
| } |
| |
| /* |
| * Setup and invoke a run of 'trigger_softirq' on the given cpu. |
| */ |
| static int raise_blk_irq(int cpu, struct request *rq) |
| { |
| if (cpu_online(cpu)) { |
| struct call_single_data *data = &rq->csd; |
| |
| data->func = trigger_softirq; |
| data->info = rq; |
| data->flags = 0; |
| |
| __smp_call_function_single(cpu, data, 0); |
| return 0; |
| } |
| |
| return 1; |
| } |
| #else /* CONFIG_SMP */ |
| static int raise_blk_irq(int cpu, struct request *rq) |
| { |
| return 1; |
| } |
| #endif |
| |
| static int __cpuinit blk_cpu_notify(struct notifier_block *self, |
| unsigned long action, void *hcpu) |
| { |
| /* |
| * If a CPU goes away, splice its entries to the current CPU |
| * and trigger a run of the softirq |
| */ |
| if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) { |
| int cpu = (unsigned long) hcpu; |
| |
| local_irq_disable(); |
| list_splice_init(&per_cpu(blk_cpu_done, cpu), |
| &__get_cpu_var(blk_cpu_done)); |
| raise_softirq_irqoff(BLOCK_SOFTIRQ); |
| local_irq_enable(); |
| } |
| |
| return NOTIFY_OK; |
| } |
| |
| static struct notifier_block __cpuinitdata blk_cpu_notifier = { |
| .notifier_call = blk_cpu_notify, |
| }; |
| |
| void __blk_complete_request(struct request *req) |
| { |
| int ccpu, cpu; |
| struct request_queue *q = req->q; |
| unsigned long flags; |
| bool shared = false; |
| |
| BUG_ON(!q->softirq_done_fn); |
| |
| local_irq_save(flags); |
| cpu = smp_processor_id(); |
| |
| /* |
| * Select completion CPU |
| */ |
| if (req->cpu != -1) { |
| ccpu = req->cpu; |
| if (!test_bit(QUEUE_FLAG_SAME_FORCE, &q->queue_flags)) |
| shared = cpus_share_cache(cpu, ccpu); |
| } else |
| ccpu = cpu; |
| |
| /* |
| * If current CPU and requested CPU share a cache, run the softirq on |
| * the current CPU. One might concern this is just like |
| * QUEUE_FLAG_SAME_FORCE, but actually not. blk_complete_request() is |
| * running in interrupt handler, and currently I/O controller doesn't |
| * support multiple interrupts, so current CPU is unique actually. This |
| * avoids IPI sending from current CPU to the first CPU of a group. |
| */ |
| if (ccpu == cpu || shared) { |
| struct list_head *list; |
| do_local: |
| list = &__get_cpu_var(blk_cpu_done); |
| list_add_tail(&req->csd.list, list); |
| |
| /* |
| * if the list only contains our just added request, |
| * signal a raise of the softirq. If there are already |
| * entries there, someone already raised the irq but it |
| * hasn't run yet. |
| */ |
| if (list->next == &req->csd.list) |
| raise_softirq_irqoff(BLOCK_SOFTIRQ); |
| } else if (raise_blk_irq(ccpu, req)) |
| goto do_local; |
| |
| local_irq_restore(flags); |
| } |
| |
| /** |
| * blk_complete_request - end I/O on a request |
| * @req: the request being processed |
| * |
| * Description: |
| * Ends all I/O on a request. It does not handle partial completions, |
| * unless the driver actually implements this in its completion callback |
| * through requeueing. The actual completion happens out-of-order, |
| * through a softirq handler. The user must have registered a completion |
| * callback through blk_queue_softirq_done(). |
| **/ |
| void blk_complete_request(struct request *req) |
| { |
| if (unlikely(blk_should_fake_timeout(req->q))) |
| return; |
| if (!blk_mark_rq_complete(req)) |
| __blk_complete_request(req); |
| } |
| EXPORT_SYMBOL(blk_complete_request); |
| |
| static __init int blk_softirq_init(void) |
| { |
| int i; |
| |
| for_each_possible_cpu(i) |
| INIT_LIST_HEAD(&per_cpu(blk_cpu_done, i)); |
| |
| open_softirq(BLOCK_SOFTIRQ, blk_done_softirq); |
| register_hotcpu_notifier(&blk_cpu_notifier); |
| return 0; |
| } |
| subsys_initcall(blk_softirq_init); |