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1// SPDX-License-Identifier: GPL-2.02/*3 * Functions related to generic timeout handling of requests.4 */5#include <linux/kernel.h>6#include <linux/module.h>7#include <linux/blkdev.h>8#include <linux/fault-inject.h>9 10#include "blk.h"11#include "blk-mq.h"12 13#ifdef CONFIG_FAIL_IO_TIMEOUT14 15static DECLARE_FAULT_ATTR(fail_io_timeout);16 17static int __init setup_fail_io_timeout(char *str)18{19 return setup_fault_attr(&fail_io_timeout, str);20}21__setup("fail_io_timeout=", setup_fail_io_timeout);22 23bool __blk_should_fake_timeout(struct request_queue *q)24{25 return should_fail(&fail_io_timeout, 1);26}27EXPORT_SYMBOL_GPL(__blk_should_fake_timeout);28 29static 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 PTR_ERR_OR_ZERO(dir);35}36 37late_initcall(fail_io_timeout_debugfs);38 39ssize_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 48ssize_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 if (val)60 blk_queue_flag_set(QUEUE_FLAG_FAIL_IO, q);61 else62 blk_queue_flag_clear(QUEUE_FLAG_FAIL_IO, q);63 }64 65 return count;66}67 68#endif /* CONFIG_FAIL_IO_TIMEOUT */69 70/**71 * blk_abort_request - Request recovery for the specified command72 * @req: pointer to the request of interest73 *74 * This function requests that the block layer start recovery for the75 * request by deleting the timer and calling the q's timeout function.76 * LLDDs who implement their own error recovery MAY ignore the timeout77 * event if they generated blk_abort_request.78 */79void blk_abort_request(struct request *req)80{81 /*82 * All we need to ensure is that timeout scan takes place83 * immediately and that scan sees the new timeout value.84 * No need for fancy synchronizations.85 */86 WRITE_ONCE(req->deadline, jiffies);87 kblockd_schedule_work(&req->q->timeout_work);88}89EXPORT_SYMBOL_GPL(blk_abort_request);90 91static unsigned long blk_timeout_mask __read_mostly;92 93static int __init blk_timeout_init(void)94{95 blk_timeout_mask = roundup_pow_of_two(HZ) - 1;96 return 0;97}98 99late_initcall(blk_timeout_init);100 101/*102 * Just a rough estimate, we don't care about specific values for timeouts.103 */104static inline unsigned long blk_round_jiffies(unsigned long j)105{106 return (j + blk_timeout_mask) + 1;107}108 109unsigned long blk_rq_timeout(unsigned long timeout)110{111 unsigned long maxt;112 113 maxt = blk_round_jiffies(jiffies + BLK_MAX_TIMEOUT);114 if (time_after(timeout, maxt))115 timeout = maxt;116 117 return timeout;118}119 120/**121 * blk_add_timer - Start timeout timer for a single request122 * @req: request that is about to start running.123 *124 * Notes:125 * Each request has its own timer, and as it is added to the queue, we126 * set up the timer. When the request completes, we cancel the timer.127 */128void blk_add_timer(struct request *req)129{130 struct request_queue *q = req->q;131 unsigned long expiry;132 133 /*134 * Some LLDs, like scsi, peek at the timeout to prevent a135 * command from being retried forever.136 */137 if (!req->timeout)138 req->timeout = q->rq_timeout;139 140 req->rq_flags &= ~RQF_TIMED_OUT;141 142 expiry = jiffies + req->timeout;143 WRITE_ONCE(req->deadline, expiry);144 145 /*146 * If the timer isn't already pending or this timeout is earlier147 * than an existing one, modify the timer. Round up to next nearest148 * second.149 */150 expiry = blk_rq_timeout(blk_round_jiffies(expiry));151 152 if (!timer_pending(&q->timeout) ||153 time_before(expiry, q->timeout.expires)) {154 unsigned long diff = q->timeout.expires - expiry;155 156 /*157 * Due to added timer slack to group timers, the timer158 * will often be a little in front of what we asked for.159 * So apply some tolerance here too, otherwise we keep160 * modifying the timer because expires for value X161 * will be X + something.162 */163 if (!timer_pending(&q->timeout) || (diff >= HZ / 2))164 mod_timer(&q->timeout, expiry);165 }166 167}168