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/*
* Functions related to generic timeout handling of requests.
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/blkdev.h>
#include "blk.h"
/*
* blk_delete_timer - Delete/cancel timer for a given function.
* @req: request that we are canceling timer for
*
*/
void blk_delete_timer(struct request *req)
{
struct request_queue *q = req->q;
/*
* Nothing to detach
*/
if (!q->rq_timed_out_fn || !req->deadline)
return;
list_del_init(&req->timeout_list);
if (list_empty(&q->timeout_list))
del_timer(&q->timeout);
}
static void blk_rq_timed_out(struct request *req)
{
struct request_queue *q = req->q;
enum blk_eh_timer_return ret;
ret = q->rq_timed_out_fn(req);
switch (ret) {
case BLK_EH_HANDLED:
__blk_complete_request(req);
break;
case BLK_EH_RESET_TIMER:
blk_clear_rq_complete(req);
blk_add_timer(req);
break;
case BLK_EH_NOT_HANDLED:
/*
* LLD handles this for now but in the future
* we can send a request msg to abort the command
* and we can move more of the generic scsi eh code to
* the blk layer.
*/
break;
default:
printk(KERN_ERR "block: bad eh return: %d\n", ret);
break;
}
}
void blk_rq_timed_out_timer(unsigned long data)
{
struct request_queue *q = (struct request_queue *) data;
unsigned long flags, uninitialized_var(next), next_set = 0;
struct request *rq, *tmp;
spin_lock_irqsave(q->queue_lock, flags);
list_for_each_entry_safe(rq, tmp, &q->timeout_list, timeout_list) {
if (time_after_eq(jiffies, rq->deadline)) {
list_del_init(&rq->timeout_list);
/*
* Check if we raced with end io completion
*/
if (blk_mark_rq_complete(rq))
continue;
blk_rq_timed_out(rq);
}
if (!next_set) {
next = rq->deadline;
next_set = 1;
} else if (time_after(next, rq->deadline))
next = rq->deadline;
}
if (next_set && !list_empty(&q->timeout_list))
mod_timer(&q->timeout, round_jiffies(next));
spin_unlock_irqrestore(q->queue_lock, flags);
}
/**
* blk_abort_request -- 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_req. Must hold queue lock.
*/
void blk_abort_request(struct request *req)
{
blk_delete_timer(req);
blk_rq_timed_out(req);
}
EXPORT_SYMBOL_GPL(blk_abort_request);
/**
* 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;
if (!q->rq_timed_out_fn)
return;
BUG_ON(!list_empty(&req->timeout_list));
BUG_ON(test_bit(REQ_ATOM_COMPLETE, &req->atomic_flags));
if (req->timeout)
req->deadline = jiffies + req->timeout;
else {
req->deadline = jiffies + q->rq_timeout;
/*
* Some LLDs, like scsi, peek at the timeout to prevent
* a command from being retried forever.
*/
req->timeout = q->rq_timeout;
}
list_add_tail(&req->timeout_list, &q->timeout_list);
/*
* If the timer isn't already pending or this timeout is earlier
* than an existing one, modify the timer. Round to next nearest
* second.
*/
expiry = round_jiffies(req->deadline);
/*
* We use ->deadline == 0 to detect whether a timer was added or
* not, so just increase to next jiffy for that specific case
*/
if (unlikely(!req->deadline))
req->deadline = 1;
if (!timer_pending(&q->timeout) ||
time_before(expiry, q->timeout.expires))
mod_timer(&q->timeout, expiry);
}
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