SAFE public projects git trees. - safe/jmp/linux-2.6/blob - block/blk-softirq.c

   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);