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>
12 #ifdef CONFIG_FAIL_IO_TIMEOUT
14 static DECLARE_FAULT_ATTR(fail_io_timeout);
16 static int __init setup_fail_io_timeout(char *str)
18 return setup_fault_attr(&fail_io_timeout, str);
20 __setup("fail_io_timeout=", setup_fail_io_timeout);
22 int blk_should_fake_timeout(struct request_queue *q)
24 if (!test_bit(QUEUE_FLAG_FAIL_IO, &q->queue_flags))
27 return should_fail(&fail_io_timeout, 1);
30 static int __init fail_io_timeout_debugfs(void)
32 struct dentry *dir = fault_create_debugfs_attr("fail_io_timeout",
33 NULL, &fail_io_timeout);
35 return PTR_ERR_OR_ZERO(dir);
38 late_initcall(fail_io_timeout_debugfs);
40 ssize_t part_timeout_show(struct device *dev, struct device_attribute *attr,
43 struct gendisk *disk = dev_to_disk(dev);
44 int set = test_bit(QUEUE_FLAG_FAIL_IO, &disk->queue->queue_flags);
46 return sprintf(buf, "%d\n", set != 0);
49 ssize_t part_timeout_store(struct device *dev, struct device_attribute *attr,
50 const char *buf, size_t count)
52 struct gendisk *disk = dev_to_disk(dev);
56 struct request_queue *q = disk->queue;
57 char *p = (char *) buf;
59 val = simple_strtoul(p, &p, 10);
60 spin_lock_irq(q->queue_lock);
62 queue_flag_set(QUEUE_FLAG_FAIL_IO, q);
64 queue_flag_clear(QUEUE_FLAG_FAIL_IO, q);
65 spin_unlock_irq(q->queue_lock);
71 #endif /* CONFIG_FAIL_IO_TIMEOUT */
74 * blk_delete_timer - Delete/cancel timer for a given function.
75 * @req: request that we are canceling timer for
78 void blk_delete_timer(struct request *req)
80 list_del_init(&req->timeout_list);
83 static void blk_rq_timed_out(struct request *req)
85 struct request_queue *q = req->q;
86 enum blk_eh_timer_return ret = BLK_EH_RESET_TIMER;
88 if (q->rq_timed_out_fn)
89 ret = q->rq_timed_out_fn(req);
92 __blk_complete_request(req);
94 case BLK_EH_RESET_TIMER:
96 blk_clear_rq_complete(req);
98 case BLK_EH_NOT_HANDLED:
100 * LLD handles this for now but in the future
101 * we can send a request msg to abort the command
102 * and we can move more of the generic scsi eh code to
107 printk(KERN_ERR "block: bad eh return: %d\n", ret);
112 static void blk_rq_check_expired(struct request *rq, unsigned long *next_timeout,
113 unsigned int *next_set)
115 if (time_after_eq(jiffies, rq->deadline)) {
116 list_del_init(&rq->timeout_list);
119 * Check if we raced with end io completion
121 if (!blk_mark_rq_complete(rq))
122 blk_rq_timed_out(rq);
123 } else if (!*next_set || time_after(*next_timeout, rq->deadline)) {
124 *next_timeout = rq->deadline;
129 void blk_timeout_work(struct work_struct *work)
131 struct request_queue *q =
132 container_of(work, struct request_queue, timeout_work);
133 unsigned long flags, next = 0;
134 struct request *rq, *tmp;
137 spin_lock_irqsave(q->queue_lock, flags);
139 list_for_each_entry_safe(rq, tmp, &q->timeout_list, timeout_list)
140 blk_rq_check_expired(rq, &next, &next_set);
143 mod_timer(&q->timeout, round_jiffies_up(next));
145 spin_unlock_irqrestore(q->queue_lock, flags);
149 * blk_abort_request -- Request request recovery for the specified command
150 * @req: pointer to the request of interest
152 * This function requests that the block layer start recovery for the
153 * request by deleting the timer and calling the q's timeout function.
154 * LLDDs who implement their own error recovery MAY ignore the timeout
155 * event if they generated blk_abort_req. Must hold queue lock.
157 void blk_abort_request(struct request *req)
159 if (req->q->mq_ops) {
161 * All we need to ensure is that timeout scan takes place
162 * immediately and that scan sees the new timeout value.
163 * No need for fancy synchronizations.
165 req->deadline = jiffies;
166 mod_timer(&req->q->timeout, 0);
168 if (blk_mark_rq_complete(req))
170 blk_delete_timer(req);
171 blk_rq_timed_out(req);
174 EXPORT_SYMBOL_GPL(blk_abort_request);
176 unsigned long blk_rq_timeout(unsigned long timeout)
180 maxt = round_jiffies_up(jiffies + BLK_MAX_TIMEOUT);
181 if (time_after(timeout, maxt))
188 * blk_add_timer - Start timeout timer for a single request
189 * @req: request that is about to start running.
192 * Each request has its own timer, and as it is added to the queue, we
193 * set up the timer. When the request completes, we cancel the timer.
195 void blk_add_timer(struct request *req)
197 struct request_queue *q = req->q;
198 unsigned long expiry;
201 lockdep_assert_held(q->queue_lock);
203 /* blk-mq has its own handler, so we don't need ->rq_timed_out_fn */
204 if (!q->mq_ops && !q->rq_timed_out_fn)
207 BUG_ON(!list_empty(&req->timeout_list));
210 * Some LLDs, like scsi, peek at the timeout to prevent a
211 * command from being retried forever.
214 req->timeout = q->rq_timeout;
216 req->deadline = jiffies + req->timeout;
217 req->rq_flags &= ~RQF_MQ_TIMEOUT_EXPIRED;
220 * Only the non-mq case needs to add the request to a protected list.
221 * For the mq case we simply scan the tag map.
224 list_add_tail(&req->timeout_list, &req->q->timeout_list);
227 * If the timer isn't already pending or this timeout is earlier
228 * than an existing one, modify the timer. Round up to next nearest
231 expiry = blk_rq_timeout(round_jiffies_up(req->deadline));
233 if (!timer_pending(&q->timeout) ||
234 time_before(expiry, q->timeout.expires)) {
235 unsigned long diff = q->timeout.expires - expiry;
238 * Due to added timer slack to group timers, the timer
239 * will often be a little in front of what we asked for.
240 * So apply some tolerance here too, otherwise we keep
241 * modifying the timer because expires for value X
242 * will be X + something.
244 if (!timer_pending(&q->timeout) || (diff >= HZ / 2))
245 mod_timer(&q->timeout, expiry);