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        list_del_init(&req->timeout_list);
  77}
  78
  79static void blk_rq_timed_out(struct request *req)
  80{
  81        struct request_queue *q = req->q;
  82        enum blk_eh_timer_return ret;
  83
  84        ret = q->rq_timed_out_fn(req);
  85        switch (ret) {
  86        case BLK_EH_HANDLED:
  87                __blk_complete_request(req);
  88                break;
  89        case BLK_EH_RESET_TIMER:
  90                blk_clear_rq_complete(req);
  91                blk_add_timer(req);
  92                break;
  93        case BLK_EH_NOT_HANDLED:
  94                /*
  95                 * LLD handles this for now but in the future
  96                 * we can send a request msg to abort the command
  97                 * and we can move more of the generic scsi eh code to
  98                 * the blk layer.
  99                 */
 100                break;
 101        default:
 102                printk(KERN_ERR "block: bad eh return: %d\n", ret);
 103                break;
 104        }
 105}
 106
 107void blk_rq_timed_out_timer(unsigned long data)
 108{
 109        struct request_queue *q = (struct request_queue *) data;
 110        unsigned long flags, next = 0;
 111        struct request *rq, *tmp;
 112
 113        spin_lock_irqsave(q->queue_lock, flags);
 114
 115        list_for_each_entry_safe(rq, tmp, &q->timeout_list, timeout_list) {
 116                if (time_after_eq(jiffies, rq->deadline)) {
 117                        list_del_init(&rq->timeout_list);
 118
 119                        /*
 120                         * Check if we raced with end io completion
 121                         */
 122                        if (blk_mark_rq_complete(rq))
 123                                continue;
 124                        blk_rq_timed_out(rq);
 125                } else {
 126                        if (!next || time_after(next, rq->deadline))
 127                                next = rq->deadline;
 128                }
 129        }
 130
 131        /*
 132         * next can never be 0 here with the list non-empty, since we always
 133         * bump ->deadline to 1 so we can detect if the timer was ever added
 134         * or not. See comment in blk_add_timer()
 135         */
 136        if (next)
 137                mod_timer(&q->timeout, round_jiffies_up(next));
 138
 139        spin_unlock_irqrestore(q->queue_lock, flags);
 140}
 141
 142/**
 143 * blk_abort_request -- Request request recovery for the specified command
 144 * @req:        pointer to the request of interest
 145 *
 146 * This function requests that the block layer start recovery for the
 147 * request by deleting the timer and calling the q's timeout function.
 148 * LLDDs who implement their own error recovery MAY ignore the timeout
 149 * event if they generated blk_abort_req. Must hold queue lock.
 150 */
 151void blk_abort_request(struct request *req)
 152{
 153        if (blk_mark_rq_complete(req))
 154                return;
 155        blk_delete_timer(req);
 156        blk_rq_timed_out(req);
 157}
 158EXPORT_SYMBOL_GPL(blk_abort_request);
 159
 160/**
 161 * blk_add_timer - Start timeout timer for a single request
 162 * @req:        request that is about to start running.
 163 *
 164 * Notes:
 165 *    Each request has its own timer, and as it is added to the queue, we
 166 *    set up the timer. When the request completes, we cancel the timer.
 167 */
 168void blk_add_timer(struct request *req)
 169{
 170        struct request_queue *q = req->q;
 171        unsigned long expiry;
 172
 173        if (!q->rq_timed_out_fn)
 174                return;
 175
 176        BUG_ON(!list_empty(&req->timeout_list));
 177        BUG_ON(test_bit(REQ_ATOM_COMPLETE, &req->atomic_flags));
 178
 179        if (req->timeout)
 180                req->deadline = jiffies + req->timeout;
 181        else {
 182                req->deadline = jiffies + q->rq_timeout;
 183                /*
 184                 * Some LLDs, like scsi, peek at the timeout to prevent
 185                 * a command from being retried forever.
 186                 */
 187                req->timeout = q->rq_timeout;
 188        }
 189        list_add_tail(&req->timeout_list, &q->timeout_list);
 190
 191        /*
 192         * If the timer isn't already pending or this timeout is earlier
 193         * than an existing one, modify the timer. Round up to next nearest
 194         * second.
 195         */
 196        expiry = round_jiffies_up(req->deadline);
 197
 198        if (!timer_pending(&q->timeout) ||
 199            time_before(expiry, q->timeout.expires))
 200                mod_timer(&q->timeout, expiry);
 201}
 202
 203/**
 204 * blk_abort_queue -- Abort all request on given queue
 205 * @queue:      pointer to queue
 206 *
 207 */
 208void blk_abort_queue(struct request_queue *q)
 209{
 210        unsigned long flags;
 211        struct request *rq, *tmp;
 212        LIST_HEAD(list);
 213
 214        spin_lock_irqsave(q->queue_lock, flags);
 215
 216        elv_abort_queue(q);
 217
 218        /*
 219         * Splice entries to local list, to avoid deadlocking if entries
 220         * get readded to the timeout list by error handling
 221         */
 222        list_splice_init(&q->timeout_list, &list);
 223
 224        list_for_each_entry_safe(rq, tmp, &list, timeout_list)
 225                blk_abort_request(rq);
 226
 227        spin_unlock_irqrestore(q->queue_lock, flags);
 228
 229}
 230EXPORT_SYMBOL_GPL(blk_abort_queue);
 231