Merge tag 'trace-3.11-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt...
[linux-2.6.git] / block / blk-timeout.c
blob65f103563969bf32391c7bb3d6f4e4859ed1459a
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>
9 #include "blk.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))
24 return 0;
26 return should_fail(&fail_io_timeout, 1);
29 static int __init fail_io_timeout_debugfs(void)
31 struct dentry *dir = fault_create_debugfs_attr("fail_io_timeout",
32 NULL, &fail_io_timeout);
34 return IS_ERR(dir) ? PTR_ERR(dir) : 0;
37 late_initcall(fail_io_timeout_debugfs);
39 ssize_t part_timeout_show(struct device *dev, struct device_attribute *attr,
40 char *buf)
42 struct gendisk *disk = dev_to_disk(dev);
43 int set = test_bit(QUEUE_FLAG_FAIL_IO, &disk->queue->queue_flags);
45 return sprintf(buf, "%d\n", set != 0);
48 ssize_t part_timeout_store(struct device *dev, struct device_attribute *attr,
49 const char *buf, size_t count)
51 struct gendisk *disk = dev_to_disk(dev);
52 int val;
54 if (count) {
55 struct request_queue *q = disk->queue;
56 char *p = (char *) buf;
58 val = simple_strtoul(p, &p, 10);
59 spin_lock_irq(q->queue_lock);
60 if (val)
61 queue_flag_set(QUEUE_FLAG_FAIL_IO, q);
62 else
63 queue_flag_clear(QUEUE_FLAG_FAIL_IO, q);
64 spin_unlock_irq(q->queue_lock);
67 return count;
70 #endif /* CONFIG_FAIL_IO_TIMEOUT */
73 * blk_delete_timer - Delete/cancel timer for a given function.
74 * @req: request that we are canceling timer for
77 void blk_delete_timer(struct request *req)
79 list_del_init(&req->timeout_list);
82 static void blk_rq_timed_out(struct request *req)
84 struct request_queue *q = req->q;
85 enum blk_eh_timer_return ret = BLK_EH_RESET_TIMER;
87 if (q->rq_timed_out_fn)
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:
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.
104 break;
105 default:
106 printk(KERN_ERR "block: bad eh return: %d\n", ret);
107 break;
111 void blk_rq_timed_out_timer(unsigned long data)
113 struct request_queue *q = (struct request_queue *) data;
114 unsigned long flags, next = 0;
115 struct request *rq, *tmp;
116 int next_set = 0;
118 spin_lock_irqsave(q->queue_lock, flags);
120 list_for_each_entry_safe(rq, tmp, &q->timeout_list, timeout_list) {
121 if (time_after_eq(jiffies, rq->deadline)) {
122 list_del_init(&rq->timeout_list);
125 * Check if we raced with end io completion
127 if (blk_mark_rq_complete(rq))
128 continue;
129 blk_rq_timed_out(rq);
130 } else if (!next_set || time_after(next, rq->deadline)) {
131 next = rq->deadline;
132 next_set = 1;
136 if (next_set)
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))
154 return;
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.
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.
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)
174 return;
176 BUG_ON(!list_empty(&req->timeout_list));
177 BUG_ON(test_bit(REQ_ATOM_COMPLETE, &req->atomic_flags));
180 * Some LLDs, like scsi, peek at the timeout to prevent a
181 * command from being retried forever.
183 if (!req->timeout)
184 req->timeout = q->rq_timeout;
186 req->deadline = jiffies + req->timeout;
187 list_add_tail(&req->timeout_list, &q->timeout_list);
190 * If the timer isn't already pending or this timeout is earlier
191 * than an existing one, modify the timer. Round up to next nearest
192 * second.
194 expiry = round_jiffies_up(req->deadline);
196 if (!timer_pending(&q->timeout) ||
197 time_before(expiry, q->timeout.expires))
198 mod_timer(&q->timeout, expiry);