linux/block/blk-timeout.c
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   1/*
   2 * Functions related to generic timeout handling of requests.
   3 */
   4#include <linux/kernel.h>
   5#include <linux/module.h>
   6#include <linux/blkdev.h>
   7#include <linux/fault-inject.h>
   8
   9#include "blk.h"
  10
  11#ifdef CONFIG_FAIL_IO_TIMEOUT
  12
  13static DECLARE_FAULT_ATTR(fail_io_timeout);
  14
  15static int __init setup_fail_io_timeout(char *str)
  16{
  17        return setup_fault_attr(&fail_io_timeout, str);
  18}
  19__setup("fail_io_timeout=", setup_fail_io_timeout);
  20
  21int blk_should_fake_timeout(struct request_queue *q)
  22{
  23        if (!test_bit(QUEUE_FLAG_FAIL_IO, &q->queue_flags))
  24                return 0;
  25
  26        return should_fail(&fail_io_timeout, 1);
  27}
  28
  29static int __init fail_io_timeout_debugfs(void)
  30{
  31        return init_fault_attr_dentries(&fail_io_timeout, "fail_io_timeout");
  32}
  33
  34late_initcall(fail_io_timeout_debugfs);
  35
  36ssize_t part_timeout_show(struct device *dev, struct device_attribute *attr,
  37                          char *buf)
  38{
  39        struct gendisk *disk = dev_to_disk(dev);
  40        int set = test_bit(QUEUE_FLAG_FAIL_IO, &disk->queue->queue_flags);
  41
  42        return sprintf(buf, "%d\n", set != 0);
  43}
  44
  45ssize_t part_timeout_store(struct device *dev, struct device_attribute *attr,
  46                           const char *buf, size_t count)
  47{
  48        struct gendisk *disk = dev_to_disk(dev);
  49        int val;
  50
  51        if (count) {
  52                struct request_queue *q = disk->queue;
  53                char *p = (char *) buf;
  54
  55                val = simple_strtoul(p, &p, 10);
  56                spin_lock_irq(q->queue_lock);
  57                if (val)
  58                        queue_flag_set(QUEUE_FLAG_FAIL_IO, q);
  59                else
  60                        queue_flag_clear(QUEUE_FLAG_FAIL_IO, q);
  61                spin_unlock_irq(q->queue_lock);
  62        }
  63
  64        return count;
  65}
  66
  67#endif /* CONFIG_FAIL_IO_TIMEOUT */
  68
  69/*
  70 * blk_delete_timer - Delete/cancel timer for a given function.
  71 * @req:        request that we are canceling timer for
  72 *
  73 */
  74void blk_delete_timer(struct request *req)
  75{
  76        struct request_queue *q = req->q;
  77
  78        list_del_init(&req->timeout_list);
  79        if (list_empty(&q->timeout_list))
  80                del_timer(&q->timeout);
  81}
  82
  83static void blk_rq_timed_out(struct request *req)
  84{
  85        struct request_queue *q = req->q;
  86        enum blk_eh_timer_return ret;
  87
  88        ret = q->rq_timed_out_fn(req);
  89        switch (ret) {
  90        case BLK_EH_HANDLED:
  91                __blk_complete_request(req);
  92                break;
  93        case BLK_EH_RESET_TIMER:
  94                blk_clear_rq_complete(req);
  95                blk_add_timer(req);
  96                break;
  97        case BLK_EH_NOT_HANDLED:
  98                /*
  99                 * LLD handles this for now but in the future
 100                 * we can send a request msg to abort the command
 101                 * and we can move more of the generic scsi eh code to
 102                 * the blk layer.
 103                 */
 104                break;
 105        default:
 106                printk(KERN_ERR "block: bad eh return: %d\n", ret);
 107                break;
 108        }
 109}
 110
 111void blk_rq_timed_out_timer(unsigned long data)
 112{
 113        struct request_queue *q = (struct request_queue *) data;
 114        unsigned long flags, uninitialized_var(next), next_set = 0;
 115        struct request *rq, *tmp;
 116
 117        spin_lock_irqsave(q->queue_lock, flags);
 118
 119        list_for_each_entry_safe(rq, tmp, &q->timeout_list, timeout_list) {
 120                if (time_after_eq(jiffies, rq->deadline)) {
 121                        list_del_init(&rq->timeout_list);
 122
 123                        /*
 124                         * Check if we raced with end io completion
 125                         */
 126                        if (blk_mark_rq_complete(rq))
 127                                continue;
 128                        blk_rq_timed_out(rq);
 129                }
 130                if (!next_set) {
 131                        next = rq->deadline;
 132                        next_set = 1;
 133                } else if (time_after(next, rq->deadline))
 134                        next = rq->deadline;
 135        }
 136
 137        if (next_set && !list_empty(&q->timeout_list))
 138                mod_timer(&q->timeout, round_jiffies_up(next));
 139
 140        spin_unlock_irqrestore(q->queue_lock, flags);
 141}
 142
 143/**
 144 * blk_abort_request -- Request request recovery for the specified command
 145 * @req:        pointer to the request of interest
 146 *
 147 * This function requests that the block layer start recovery for the
 148 * request by deleting the timer and calling the q's timeout function.
 149 * LLDDs who implement their own error recovery MAY ignore the timeout
 150 * event if they generated blk_abort_req. Must hold queue lock.
 151 */
 152void blk_abort_request(struct request *req)
 153{
 154        if (blk_mark_rq_complete(req))
 155                return;
 156        blk_delete_timer(req);
 157        blk_rq_timed_out(req);
 158}
 159EXPORT_SYMBOL_GPL(blk_abort_request);
 160
 161/**
 162 * blk_add_timer - Start timeout timer for a single request
 163 * @req:        request that is about to start running.
 164 *
 165 * Notes:
 166 *    Each request has its own timer, and as it is added to the queue, we
 167 *    set up the timer. When the request completes, we cancel the timer.
 168 */
 169void blk_add_timer(struct request *req)
 170{
 171        struct request_queue *q = req->q;
 172        unsigned long expiry;
 173
 174        if (!q->rq_timed_out_fn)
 175                return;
 176
 177        BUG_ON(!list_empty(&req->timeout_list));
 178        BUG_ON(test_bit(REQ_ATOM_COMPLETE, &req->atomic_flags));
 179
 180        if (req->timeout)
 181                req->deadline = jiffies + req->timeout;
 182        else {
 183                req->deadline = jiffies + q->rq_timeout;
 184                /*
 185                 * Some LLDs, like scsi, peek at the timeout to prevent
 186                 * a command from being retried forever.
 187                 */
 188                req->timeout = q->rq_timeout;
 189        }
 190        list_add_tail(&req->timeout_list, &q->timeout_list);
 191
 192        /*
 193         * If the timer isn't already pending or this timeout is earlier
 194         * than an existing one, modify the timer. Round up to next nearest
 195         * second.
 196         */
 197        expiry = round_jiffies_up(req->deadline);
 198
 199        if (!timer_pending(&q->timeout) ||
 200            time_before(expiry, q->timeout.expires))
 201                mod_timer(&q->timeout, expiry);
 202}
 203
 204/**
 205 * blk_abort_queue -- Abort all request on given queue
 206 * @queue:      pointer to queue
 207 *
 208 */
 209void blk_abort_queue(struct request_queue *q)
 210{
 211        unsigned long flags;
 212        struct request *rq, *tmp;
 213
 214        spin_lock_irqsave(q->queue_lock, flags);
 215
 216        elv_abort_queue(q);
 217
 218        list_for_each_entry_safe(rq, tmp, &q->timeout_list, timeout_list)
 219                blk_abort_request(rq);
 220
 221        spin_unlock_irqrestore(q->queue_lock, flags);
 222
 223}
 224EXPORT_SYMBOL_GPL(blk_abort_queue);
 225
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