block/blk-timeout.c

   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
  13 static DECLARE_FAULT_ATTR(fail_io_timeout);
  14
  15 static 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
  21 int 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
  29 static int __init fail_io_timeout_debugfs(void)
  30 {
  31         return init_fault_attr_dentries(&fail_io_timeout, "fail_io_timeout");
  32 }
  33
  34 late_initcall(fail_io_timeout_debugfs);
  35
  36 ssize_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
  45 ssize_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  */
  74 void blk_delete_timer(struct request *req)
  75 {
  76         list_del_init(&req->timeout_list);
  77 }
  78
  79 static 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
 107 void 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  */
 151 void 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 }
 158 EXPORT_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  */
 168 void 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  */
 208 void blk_abort_queue(struct request_queue *q)
 209 {
 210         unsigned long flags;
 211         struct request *rq, *tmp;
 212         LIST_HEAD(list);
 213
 214         /*
 215          * Not a request based block device, nothing to abort
 216          */
 217         if (!q->request_fn)
 218                 return;
 219
 220         spin_lock_irqsave(q->queue_lock, flags);
 221
 222         elv_abort_queue(q);
 223
 224         /*
 225          * Splice entries to local list, to avoid deadlocking if entries
 226          * get readded to the timeout list by error handling
 227          */
 228         list_splice_init(&q->timeout_list, &list);
 229
 230         list_for_each_entry_safe(rq, tmp, &list, timeout_list)
 231                 blk_abort_request(rq);
 232
 233         /*
 234          * Occasionally, blk_abort_request() will return without
 235          * deleting the element from the list. Make sure we add those back
 236          * instead of leaving them on the local stack list.
 237          */
 238         list_splice(&list, &q->timeout_list);
 239
 240         spin_unlock_irqrestore(q->queue_lock, flags);
 241
 242 }
 243 EXPORT_SYMBOL_GPL(blk_abort_queue);