2 * Functions related to generic timeout handling of requests.
4 #include <linux/kernel.h>
5 #include <linux/module.h>
6 #include <linux/blkdev.h>
7 #include <linux/fault-inject.h>
11 #ifdef CONFIG_FAIL_IO_TIMEOUT
13 static DECLARE_FAULT_ATTR(fail_io_timeout);
15 static int __init setup_fail_io_timeout(char *str)
17 return setup_fault_attr(&fail_io_timeout, str);
19 __setup("fail_io_timeout=", setup_fail_io_timeout);
21 int blk_should_fake_timeout(struct request_queue *q)
23 if (!test_bit(QUEUE_FLAG_FAIL_IO, &q->queue_flags))
26 return should_fail(&fail_io_timeout, 1);
29 static int __init fail_io_timeout_debugfs(void)
31 return init_fault_attr_dentries(&fail_io_timeout, "fail_io_timeout");
34 late_initcall(fail_io_timeout_debugfs);
36 ssize_t part_timeout_show(struct device *dev, struct device_attribute *attr,
39 struct gendisk *disk = dev_to_disk(dev);
40 int set = test_bit(QUEUE_FLAG_FAIL_IO, &disk->queue->queue_flags);
42 return sprintf(buf, "%d\n", set != 0);
45 ssize_t part_timeout_store(struct device *dev, struct device_attribute *attr,
46 const char *buf, size_t count)
48 struct gendisk *disk = dev_to_disk(dev);
52 struct request_queue *q = disk->queue;
53 char *p = (char *) buf;
55 val = simple_strtoul(p, &p, 10);
56 spin_lock_irq(q->queue_lock);
58 queue_flag_set(QUEUE_FLAG_FAIL_IO, q);
60 queue_flag_clear(QUEUE_FLAG_FAIL_IO, q);
61 spin_unlock_irq(q->queue_lock);
67 #endif /* CONFIG_FAIL_IO_TIMEOUT */
70 * blk_delete_timer - Delete/cancel timer for a given function.
71 * @req: request that we are canceling timer for
74 void blk_delete_timer(struct request *req)
76 list_del_init(&req->timeout_list);
79 static void blk_rq_timed_out(struct request *req)
81 struct request_queue *q = req->q;
82 enum blk_eh_timer_return ret;
84 ret = q->rq_timed_out_fn(req);
87 __blk_complete_request(req);
89 case BLK_EH_RESET_TIMER:
90 blk_clear_rq_complete(req);
93 case BLK_EH_NOT_HANDLED:
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
102 printk(KERN_ERR "block: bad eh return: %d\n", ret);
107 void blk_rq_timed_out_timer(unsigned long data)
109 struct request_queue *q = (struct request_queue *) data;
110 unsigned long flags, next = 0;
111 struct request *rq, *tmp;
113 spin_lock_irqsave(q->queue_lock, flags);
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);
120 * Check if we raced with end io completion
122 if (blk_mark_rq_complete(rq))
124 blk_rq_timed_out(rq);
126 if (!next || time_after(next, rq->deadline))
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()
137 mod_timer(&q->timeout, round_jiffies_up(next));
139 spin_unlock_irqrestore(q->queue_lock, flags);
143 * blk_abort_request -- Request request recovery for the specified command
144 * @req: pointer to the request of interest
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.
151 void blk_abort_request(struct request *req)
153 if (blk_mark_rq_complete(req))
155 blk_delete_timer(req);
156 blk_rq_timed_out(req);
158 EXPORT_SYMBOL_GPL(blk_abort_request);
161 * blk_add_timer - Start timeout timer for a single request
162 * @req: request that is about to start running.
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.
168 void blk_add_timer(struct request *req)
170 struct request_queue *q = req->q;
171 unsigned long expiry;
173 if (!q->rq_timed_out_fn)
176 BUG_ON(!list_empty(&req->timeout_list));
177 BUG_ON(test_bit(REQ_ATOM_COMPLETE, &req->atomic_flags));
180 req->deadline = jiffies + req->timeout;
182 req->deadline = jiffies + q->rq_timeout;
184 * Some LLDs, like scsi, peek at the timeout to prevent
185 * a command from being retried forever.
187 req->timeout = q->rq_timeout;
189 list_add_tail(&req->timeout_list, &q->timeout_list);
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
196 expiry = round_jiffies_up(req->deadline);
198 if (!timer_pending(&q->timeout) ||
199 time_before(expiry, q->timeout.expires))
200 mod_timer(&q->timeout, expiry);
204 * blk_abort_queue -- Abort all request on given queue
205 * @queue: pointer to queue
208 void blk_abort_queue(struct request_queue *q)
211 struct request *rq, *tmp;
215 * Not a request based block device, nothing to abort
220 spin_lock_irqsave(q->queue_lock, flags);
225 * Splice entries to local list, to avoid deadlocking if entries
226 * get readded to the timeout list by error handling
228 list_splice_init(&q->timeout_list, &list);
230 list_for_each_entry_safe(rq, tmp, &list, timeout_list)
231 blk_abort_request(rq);
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.
238 list_splice(&list, &q->timeout_list);
240 spin_unlock_irqrestore(q->queue_lock, flags);
243 EXPORT_SYMBOL_GPL(blk_abort_queue);