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- // SPDX-License-Identifier: GPL-2.0
- /*
- * Functions related to generic timeout handling of requests.
- */
- #include <linux/kernel.h>
- #include <linux/module.h>
- #include <linux/blkdev.h>
- #include <linux/fault-inject.h>
- #include "blk.h"
- #include "blk-mq.h"
- #ifdef CONFIG_FAIL_IO_TIMEOUT
- static DECLARE_FAULT_ATTR(fail_io_timeout);
- static int __init setup_fail_io_timeout(char *str)
- {
- return setup_fault_attr(&fail_io_timeout, str);
- }
- __setup("fail_io_timeout=", setup_fail_io_timeout);
- bool __blk_should_fake_timeout(struct request_queue *q)
- {
- return should_fail(&fail_io_timeout, 1);
- }
- EXPORT_SYMBOL_GPL(__blk_should_fake_timeout);
- static int __init fail_io_timeout_debugfs(void)
- {
- struct dentry *dir = fault_create_debugfs_attr("fail_io_timeout",
- NULL, &fail_io_timeout);
- return PTR_ERR_OR_ZERO(dir);
- }
- late_initcall(fail_io_timeout_debugfs);
- ssize_t part_timeout_show(struct device *dev, struct device_attribute *attr,
- char *buf)
- {
- struct gendisk *disk = dev_to_disk(dev);
- int set = test_bit(QUEUE_FLAG_FAIL_IO, &disk->queue->queue_flags);
- return sprintf(buf, "%d\n", set != 0);
- }
- ssize_t part_timeout_store(struct device *dev, struct device_attribute *attr,
- const char *buf, size_t count)
- {
- struct gendisk *disk = dev_to_disk(dev);
- int val;
- if (count) {
- struct request_queue *q = disk->queue;
- char *p = (char *) buf;
- val = simple_strtoul(p, &p, 10);
- if (val)
- blk_queue_flag_set(QUEUE_FLAG_FAIL_IO, q);
- else
- blk_queue_flag_clear(QUEUE_FLAG_FAIL_IO, q);
- }
- return count;
- }
- #endif /* CONFIG_FAIL_IO_TIMEOUT */
- /**
- * blk_abort_request - Request recovery for the specified command
- * @req: pointer to the request of interest
- *
- * This function requests that the block layer start recovery for the
- * request by deleting the timer and calling the q's timeout function.
- * LLDDs who implement their own error recovery MAY ignore the timeout
- * event if they generated blk_abort_request.
- */
- void blk_abort_request(struct request *req)
- {
- /*
- * All we need to ensure is that timeout scan takes place
- * immediately and that scan sees the new timeout value.
- * No need for fancy synchronizations.
- */
- WRITE_ONCE(req->deadline, jiffies);
- kblockd_schedule_work(&req->q->timeout_work);
- }
- EXPORT_SYMBOL_GPL(blk_abort_request);
- static unsigned long blk_timeout_mask __read_mostly;
- static int __init blk_timeout_init(void)
- {
- blk_timeout_mask = roundup_pow_of_two(HZ) - 1;
- return 0;
- }
- late_initcall(blk_timeout_init);
- /*
- * Just a rough estimate, we don't care about specific values for timeouts.
- */
- static inline unsigned long blk_round_jiffies(unsigned long j)
- {
- return (j + blk_timeout_mask) + 1;
- }
- unsigned long blk_rq_timeout(unsigned long timeout)
- {
- unsigned long maxt;
- maxt = blk_round_jiffies(jiffies + BLK_MAX_TIMEOUT);
- if (time_after(timeout, maxt))
- timeout = maxt;
- return timeout;
- }
- /**
- * blk_add_timer - Start timeout timer for a single request
- * @req: request that is about to start running.
- *
- * Notes:
- * Each request has its own timer, and as it is added to the queue, we
- * set up the timer. When the request completes, we cancel the timer.
- */
- void blk_add_timer(struct request *req)
- {
- struct request_queue *q = req->q;
- unsigned long expiry;
- /*
- * Some LLDs, like scsi, peek at the timeout to prevent a
- * command from being retried forever.
- */
- if (!req->timeout)
- req->timeout = q->rq_timeout;
- req->rq_flags &= ~RQF_TIMED_OUT;
- expiry = jiffies + req->timeout;
- WRITE_ONCE(req->deadline, expiry);
- /*
- * If the timer isn't already pending or this timeout is earlier
- * than an existing one, modify the timer. Round up to next nearest
- * second.
- */
- expiry = blk_rq_timeout(blk_round_jiffies(expiry));
- if (!timer_pending(&q->timeout) ||
- time_before(expiry, q->timeout.expires)) {
- unsigned long diff = q->timeout.expires - expiry;
- /*
- * Due to added timer slack to group timers, the timer
- * will often be a little in front of what we asked for.
- * So apply some tolerance here too, otherwise we keep
- * modifying the timer because expires for value X
- * will be X + something.
- */
- if (!timer_pending(&q->timeout) || (diff >= HZ / 2))
- mod_timer(&q->timeout, expiry);
- }
- }
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