forked from luck/tmp_suning_uos_patched
d50235b7bc
There's a race between elevator switching and normal io operation.
Because the allocation of struct elevator_queue and struct elevator_data
don't in a atomic operation.So there are have chance to use NULL
->elevator_data.
For example:
Thread A: Thread B
blk_queu_bio elevator_switch
spin_lock_irq(q->queue_block) elevator_alloc
elv_merge elevator_init_fn
Because call elevator_alloc, it can't hold queue_lock and the
->elevator_data is NULL.So at the same time, threadA call elv_merge and
nedd some info of elevator_data.So the crash happened.
Move the elevator_alloc into func elevator_init_fn, it make the
operations in a atomic operation.
Using the follow method can easy reproduce this bug
1:dd if=/dev/sdb of=/dev/null
2:while true;do echo noop > scheduler;echo deadline > scheduler;done
The test method also use this method.
Signed-off-by: Jianpeng Ma <majianpeng@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
223 lines
7.2 KiB
C
223 lines
7.2 KiB
C
#ifndef _LINUX_ELEVATOR_H
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#define _LINUX_ELEVATOR_H
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#include <linux/percpu.h>
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#include <linux/hashtable.h>
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#ifdef CONFIG_BLOCK
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struct io_cq;
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struct elevator_type;
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typedef int (elevator_merge_fn) (struct request_queue *, struct request **,
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struct bio *);
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typedef void (elevator_merge_req_fn) (struct request_queue *, struct request *, struct request *);
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typedef void (elevator_merged_fn) (struct request_queue *, struct request *, int);
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typedef int (elevator_allow_merge_fn) (struct request_queue *, struct request *, struct bio *);
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typedef void (elevator_bio_merged_fn) (struct request_queue *,
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struct request *, struct bio *);
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typedef int (elevator_dispatch_fn) (struct request_queue *, int);
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typedef void (elevator_add_req_fn) (struct request_queue *, struct request *);
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typedef struct request *(elevator_request_list_fn) (struct request_queue *, struct request *);
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typedef void (elevator_completed_req_fn) (struct request_queue *, struct request *);
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typedef int (elevator_may_queue_fn) (struct request_queue *, int);
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typedef void (elevator_init_icq_fn) (struct io_cq *);
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typedef void (elevator_exit_icq_fn) (struct io_cq *);
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typedef int (elevator_set_req_fn) (struct request_queue *, struct request *,
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struct bio *, gfp_t);
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typedef void (elevator_put_req_fn) (struct request *);
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typedef void (elevator_activate_req_fn) (struct request_queue *, struct request *);
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typedef void (elevator_deactivate_req_fn) (struct request_queue *, struct request *);
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typedef int (elevator_init_fn) (struct request_queue *,
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struct elevator_type *e);
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typedef void (elevator_exit_fn) (struct elevator_queue *);
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struct elevator_ops
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{
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elevator_merge_fn *elevator_merge_fn;
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elevator_merged_fn *elevator_merged_fn;
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elevator_merge_req_fn *elevator_merge_req_fn;
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elevator_allow_merge_fn *elevator_allow_merge_fn;
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elevator_bio_merged_fn *elevator_bio_merged_fn;
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elevator_dispatch_fn *elevator_dispatch_fn;
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elevator_add_req_fn *elevator_add_req_fn;
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elevator_activate_req_fn *elevator_activate_req_fn;
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elevator_deactivate_req_fn *elevator_deactivate_req_fn;
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elevator_completed_req_fn *elevator_completed_req_fn;
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elevator_request_list_fn *elevator_former_req_fn;
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elevator_request_list_fn *elevator_latter_req_fn;
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elevator_init_icq_fn *elevator_init_icq_fn; /* see iocontext.h */
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elevator_exit_icq_fn *elevator_exit_icq_fn; /* ditto */
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elevator_set_req_fn *elevator_set_req_fn;
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elevator_put_req_fn *elevator_put_req_fn;
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elevator_may_queue_fn *elevator_may_queue_fn;
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elevator_init_fn *elevator_init_fn;
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elevator_exit_fn *elevator_exit_fn;
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};
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#define ELV_NAME_MAX (16)
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struct elv_fs_entry {
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struct attribute attr;
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ssize_t (*show)(struct elevator_queue *, char *);
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ssize_t (*store)(struct elevator_queue *, const char *, size_t);
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};
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/*
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* identifies an elevator type, such as AS or deadline
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*/
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struct elevator_type
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{
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/* managed by elevator core */
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struct kmem_cache *icq_cache;
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/* fields provided by elevator implementation */
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struct elevator_ops ops;
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size_t icq_size; /* see iocontext.h */
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size_t icq_align; /* ditto */
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struct elv_fs_entry *elevator_attrs;
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char elevator_name[ELV_NAME_MAX];
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struct module *elevator_owner;
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/* managed by elevator core */
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char icq_cache_name[ELV_NAME_MAX + 5]; /* elvname + "_io_cq" */
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struct list_head list;
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};
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#define ELV_HASH_BITS 6
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/*
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* each queue has an elevator_queue associated with it
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*/
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struct elevator_queue
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{
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struct elevator_type *type;
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void *elevator_data;
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struct kobject kobj;
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struct mutex sysfs_lock;
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unsigned int registered:1;
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DECLARE_HASHTABLE(hash, ELV_HASH_BITS);
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};
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/*
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* block elevator interface
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*/
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extern void elv_dispatch_sort(struct request_queue *, struct request *);
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extern void elv_dispatch_add_tail(struct request_queue *, struct request *);
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extern void elv_add_request(struct request_queue *, struct request *, int);
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extern void __elv_add_request(struct request_queue *, struct request *, int);
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extern int elv_merge(struct request_queue *, struct request **, struct bio *);
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extern void elv_merge_requests(struct request_queue *, struct request *,
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struct request *);
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extern void elv_merged_request(struct request_queue *, struct request *, int);
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extern void elv_bio_merged(struct request_queue *q, struct request *,
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struct bio *);
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extern void elv_requeue_request(struct request_queue *, struct request *);
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extern struct request *elv_former_request(struct request_queue *, struct request *);
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extern struct request *elv_latter_request(struct request_queue *, struct request *);
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extern int elv_register_queue(struct request_queue *q);
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extern void elv_unregister_queue(struct request_queue *q);
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extern int elv_may_queue(struct request_queue *, int);
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extern void elv_abort_queue(struct request_queue *);
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extern void elv_completed_request(struct request_queue *, struct request *);
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extern int elv_set_request(struct request_queue *q, struct request *rq,
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struct bio *bio, gfp_t gfp_mask);
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extern void elv_put_request(struct request_queue *, struct request *);
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extern void elv_drain_elevator(struct request_queue *);
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/*
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* io scheduler registration
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*/
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extern void __init load_default_elevator_module(void);
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extern int elv_register(struct elevator_type *);
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extern void elv_unregister(struct elevator_type *);
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/*
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* io scheduler sysfs switching
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*/
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extern ssize_t elv_iosched_show(struct request_queue *, char *);
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extern ssize_t elv_iosched_store(struct request_queue *, const char *, size_t);
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extern int elevator_init(struct request_queue *, char *);
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extern void elevator_exit(struct elevator_queue *);
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extern int elevator_change(struct request_queue *, const char *);
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extern bool elv_rq_merge_ok(struct request *, struct bio *);
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extern struct elevator_queue *elevator_alloc(struct request_queue *,
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struct elevator_type *);
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/*
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* Helper functions.
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*/
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extern struct request *elv_rb_former_request(struct request_queue *, struct request *);
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extern struct request *elv_rb_latter_request(struct request_queue *, struct request *);
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/*
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* rb support functions.
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*/
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extern void elv_rb_add(struct rb_root *, struct request *);
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extern void elv_rb_del(struct rb_root *, struct request *);
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extern struct request *elv_rb_find(struct rb_root *, sector_t);
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/*
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* Return values from elevator merger
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*/
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#define ELEVATOR_NO_MERGE 0
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#define ELEVATOR_FRONT_MERGE 1
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#define ELEVATOR_BACK_MERGE 2
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/*
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* Insertion selection
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*/
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#define ELEVATOR_INSERT_FRONT 1
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#define ELEVATOR_INSERT_BACK 2
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#define ELEVATOR_INSERT_SORT 3
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#define ELEVATOR_INSERT_REQUEUE 4
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#define ELEVATOR_INSERT_FLUSH 5
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#define ELEVATOR_INSERT_SORT_MERGE 6
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/*
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* return values from elevator_may_queue_fn
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*/
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enum {
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ELV_MQUEUE_MAY,
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ELV_MQUEUE_NO,
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ELV_MQUEUE_MUST,
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};
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#define rq_end_sector(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq))
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#define rb_entry_rq(node) rb_entry((node), struct request, rb_node)
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/*
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* Hack to reuse the csd.list list_head as the fifo time holder while
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* the request is in the io scheduler. Saves an unsigned long in rq.
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*/
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#define rq_fifo_time(rq) ((unsigned long) (rq)->csd.list.next)
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#define rq_set_fifo_time(rq,exp) ((rq)->csd.list.next = (void *) (exp))
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#define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
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#define rq_fifo_clear(rq) do { \
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list_del_init(&(rq)->queuelist); \
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INIT_LIST_HEAD(&(rq)->csd.list); \
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} while (0)
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#else /* CONFIG_BLOCK */
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static inline void load_default_elevator_module(void) { }
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#endif /* CONFIG_BLOCK */
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#endif
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