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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 | |
| 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 | struct dentry *dir = fault_create_debugfs_attr("fail_io_timeout", |
| 32 | NULL, &fail_io_timeout); |
| 33 | |
| 34 | return IS_ERR(dir) ? PTR_ERR(dir) : 0; |
| 35 | } |
| 36 | |
| 37 | late_initcall(fail_io_timeout_debugfs); |
| 38 | |
| 39 | ssize_t part_timeout_show(struct device *dev, struct device_attribute *attr, |
| 40 | char *buf) |
| 41 | { |
| 42 | struct gendisk *disk = dev_to_disk(dev); |
| 43 | int set = test_bit(QUEUE_FLAG_FAIL_IO, &disk->queue->queue_flags); |
| 44 | |
| 45 | return sprintf(buf, "%d\n", set != 0); |
| 46 | } |
| 47 | |
| 48 | ssize_t part_timeout_store(struct device *dev, struct device_attribute *attr, |
| 49 | const char *buf, size_t count) |
| 50 | { |
| 51 | struct gendisk *disk = dev_to_disk(dev); |
| 52 | int val; |
| 53 | |
| 54 | if (count) { |
| 55 | struct request_queue *q = disk->queue; |
| 56 | char *p = (char *) buf; |
| 57 | |
| 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); |
| 65 | } |
| 66 | |
| 67 | return count; |
| 68 | } |
| 69 | |
| 70 | #endif /* CONFIG_FAIL_IO_TIMEOUT */ |
| 71 | |
| 72 | /* |
| 73 | * blk_delete_timer - Delete/cancel timer for a given function. |
| 74 | * @req: request that we are canceling timer for |
| 75 | * |
| 76 | */ |
| 77 | void blk_delete_timer(struct request *req) |
| 78 | { |
| 79 | list_del_init(&req->timeout_list); |
| 80 | } |
| 81 | |
| 82 | static void blk_rq_timed_out(struct request *req) |
| 83 | { |
| 84 | struct request_queue *q = req->q; |
| 85 | enum blk_eh_timer_return ret; |
| 86 | |
| 87 | ret = q->rq_timed_out_fn(req); |
| 88 | switch (ret) { |
| 89 | case BLK_EH_HANDLED: |
| 90 | __blk_complete_request(req); |
| 91 | break; |
| 92 | case BLK_EH_RESET_TIMER: |
| 93 | blk_clear_rq_complete(req); |
| 94 | blk_add_timer(req); |
| 95 | break; |
| 96 | case BLK_EH_NOT_HANDLED: |
| 97 | /* |
| 98 | * LLD handles this for now but in the future |
| 99 | * we can send a request msg to abort the command |
| 100 | * and we can move more of the generic scsi eh code to |
| 101 | * the blk layer. |
| 102 | */ |
| 103 | break; |
| 104 | default: |
| 105 | printk(KERN_ERR "block: bad eh return: %d\n", ret); |
| 106 | break; |
| 107 | } |
| 108 | } |
| 109 | |
| 110 | void blk_rq_timed_out_timer(unsigned long data) |
| 111 | { |
| 112 | struct request_queue *q = (struct request_queue *) data; |
| 113 | unsigned long flags, next = 0; |
| 114 | struct request *rq, *tmp; |
| 115 | int next_set = 0; |
| 116 | |
| 117 | spin_lock_irqsave(q->queue_lock, flags); |
| 118 | |
| 119 | list_for_each_entry_safe(rq, tmp, &q->timeout_list, timeout_list) { |
| 120 | if (time_after_eq(jiffies, rq->deadline)) { |
| 121 | list_del_init(&rq->timeout_list); |
| 122 | |
| 123 | /* |
| 124 | * Check if we raced with end io completion |
| 125 | */ |
| 126 | if (blk_mark_rq_complete(rq)) |
| 127 | continue; |
| 128 | blk_rq_timed_out(rq); |
| 129 | } else if (!next_set || time_after(next, rq->deadline)) { |
| 130 | next = rq->deadline; |
| 131 | next_set = 1; |
| 132 | } |
| 133 | } |
| 134 | |
| 135 | if (next_set) |
| 136 | mod_timer(&q->timeout, round_jiffies_up(next)); |
| 137 | |
| 138 | spin_unlock_irqrestore(q->queue_lock, flags); |
| 139 | } |
| 140 | |
| 141 | /** |
| 142 | * blk_abort_request -- Request request recovery for the specified command |
| 143 | * @req: pointer to the request of interest |
| 144 | * |
| 145 | * This function requests that the block layer start recovery for the |
| 146 | * request by deleting the timer and calling the q's timeout function. |
| 147 | * LLDDs who implement their own error recovery MAY ignore the timeout |
| 148 | * event if they generated blk_abort_req. Must hold queue lock. |
| 149 | */ |
| 150 | void blk_abort_request(struct request *req) |
| 151 | { |
| 152 | if (blk_mark_rq_complete(req)) |
| 153 | return; |
| 154 | blk_delete_timer(req); |
| 155 | blk_rq_timed_out(req); |
| 156 | } |
| 157 | EXPORT_SYMBOL_GPL(blk_abort_request); |
| 158 | |
| 159 | /** |
| 160 | * blk_add_timer - Start timeout timer for a single request |
| 161 | * @req: request that is about to start running. |
| 162 | * |
| 163 | * Notes: |
| 164 | * Each request has its own timer, and as it is added to the queue, we |
| 165 | * set up the timer. When the request completes, we cancel the timer. |
| 166 | */ |
| 167 | void blk_add_timer(struct request *req) |
| 168 | { |
| 169 | struct request_queue *q = req->q; |
| 170 | unsigned long expiry; |
| 171 | |
| 172 | if (!q->rq_timed_out_fn) |
| 173 | return; |
| 174 | |
| 175 | BUG_ON(!list_empty(&req->timeout_list)); |
| 176 | BUG_ON(test_bit(REQ_ATOM_COMPLETE, &req->atomic_flags)); |
| 177 | |
| 178 | /* |
| 179 | * Some LLDs, like scsi, peek at the timeout to prevent a |
| 180 | * command from being retried forever. |
| 181 | */ |
| 182 | if (!req->timeout) |
| 183 | req->timeout = q->rq_timeout; |
| 184 | |
| 185 | req->deadline = jiffies + req->timeout; |
| 186 | list_add_tail(&req->timeout_list, &q->timeout_list); |
| 187 | |
| 188 | /* |
| 189 | * If the timer isn't already pending or this timeout is earlier |
| 190 | * than an existing one, modify the timer. Round up to next nearest |
| 191 | * second. |
| 192 | */ |
| 193 | expiry = round_jiffies_up(req->deadline); |
| 194 | |
| 195 | if (!timer_pending(&q->timeout) || |
| 196 | time_before(expiry, q->timeout.expires)) |
| 197 | mod_timer(&q->timeout, expiry); |
| 198 | } |
| 199 | |
| 200 |
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