mirror of https://gitee.com/openkylin/linux.git
184 lines
4.4 KiB
C
184 lines
4.4 KiB
C
/*
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* zfcp device driver
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*
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* Data structure and helper functions for tracking pending FSF
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* requests.
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*
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* Copyright IBM Corp. 2009
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*/
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#ifndef ZFCP_REQLIST_H
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#define ZFCP_REQLIST_H
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/* number of hash buckets */
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#define ZFCP_REQ_LIST_BUCKETS 128
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/**
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* struct zfcp_reqlist - Container for request list (reqlist)
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* @lock: Spinlock for protecting the hash list
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* @list: Array of hashbuckets, each is a list of requests in this bucket
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*/
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struct zfcp_reqlist {
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spinlock_t lock;
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struct list_head buckets[ZFCP_REQ_LIST_BUCKETS];
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};
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static inline int zfcp_reqlist_hash(unsigned long req_id)
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{
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return req_id % ZFCP_REQ_LIST_BUCKETS;
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}
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/**
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* zfcp_reqlist_alloc - Allocate and initialize reqlist
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*
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* Returns pointer to allocated reqlist on success, or NULL on
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* allocation failure.
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*/
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static inline struct zfcp_reqlist *zfcp_reqlist_alloc(void)
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{
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unsigned int i;
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struct zfcp_reqlist *rl;
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rl = kzalloc(sizeof(struct zfcp_reqlist), GFP_KERNEL);
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if (!rl)
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return NULL;
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spin_lock_init(&rl->lock);
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for (i = 0; i < ZFCP_REQ_LIST_BUCKETS; i++)
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INIT_LIST_HEAD(&rl->buckets[i]);
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return rl;
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}
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/**
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* zfcp_reqlist_isempty - Check whether the request list empty
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* @rl: pointer to reqlist
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*
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* Returns: 1 if list is empty, 0 if not
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*/
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static inline int zfcp_reqlist_isempty(struct zfcp_reqlist *rl)
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{
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unsigned int i;
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for (i = 0; i < ZFCP_REQ_LIST_BUCKETS; i++)
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if (!list_empty(&rl->buckets[i]))
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return 0;
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return 1;
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}
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/**
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* zfcp_reqlist_free - Free allocated memory for reqlist
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* @rl: The reqlist where to free memory
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*/
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static inline void zfcp_reqlist_free(struct zfcp_reqlist *rl)
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{
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/* sanity check */
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BUG_ON(!zfcp_reqlist_isempty(rl));
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kfree(rl);
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}
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static inline struct zfcp_fsf_req *
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_zfcp_reqlist_find(struct zfcp_reqlist *rl, unsigned long req_id)
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{
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struct zfcp_fsf_req *req;
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unsigned int i;
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i = zfcp_reqlist_hash(req_id);
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list_for_each_entry(req, &rl->buckets[i], list)
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if (req->req_id == req_id)
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return req;
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return NULL;
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}
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/**
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* zfcp_reqlist_find - Lookup FSF request by its request id
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* @rl: The reqlist where to lookup the FSF request
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* @req_id: The request id to look for
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*
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* Returns a pointer to the FSF request with the specified request id
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* or NULL if there is no known FSF request with this id.
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*/
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static inline struct zfcp_fsf_req *
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zfcp_reqlist_find(struct zfcp_reqlist *rl, unsigned long req_id)
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{
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unsigned long flags;
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struct zfcp_fsf_req *req;
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spin_lock_irqsave(&rl->lock, flags);
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req = _zfcp_reqlist_find(rl, req_id);
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spin_unlock_irqrestore(&rl->lock, flags);
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return req;
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}
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/**
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* zfcp_reqlist_find_rm - Lookup request by id and remove it from reqlist
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* @rl: reqlist where to search and remove entry
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* @req_id: The request id of the request to look for
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*
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* This functions tries to find the FSF request with the specified
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* id and then removes it from the reqlist. The reqlist lock is held
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* during both steps of the operation.
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*
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* Returns: Pointer to the FSF request if the request has been found,
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* NULL if it has not been found.
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*/
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static inline struct zfcp_fsf_req *
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zfcp_reqlist_find_rm(struct zfcp_reqlist *rl, unsigned long req_id)
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{
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unsigned long flags;
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struct zfcp_fsf_req *req;
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spin_lock_irqsave(&rl->lock, flags);
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req = _zfcp_reqlist_find(rl, req_id);
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if (req)
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list_del(&req->list);
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spin_unlock_irqrestore(&rl->lock, flags);
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return req;
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}
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/**
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* zfcp_reqlist_add - Add entry to reqlist
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* @rl: reqlist where to add the entry
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* @req: The entry to add
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*
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* The request id always increases. As an optimization new requests
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* are added here with list_add_tail at the end of the bucket lists
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* while old requests are looked up starting at the beginning of the
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* lists.
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*/
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static inline void zfcp_reqlist_add(struct zfcp_reqlist *rl,
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struct zfcp_fsf_req *req)
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{
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unsigned int i;
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unsigned long flags;
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i = zfcp_reqlist_hash(req->req_id);
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spin_lock_irqsave(&rl->lock, flags);
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list_add_tail(&req->list, &rl->buckets[i]);
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spin_unlock_irqrestore(&rl->lock, flags);
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}
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/**
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* zfcp_reqlist_move - Move all entries from reqlist to simple list
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* @rl: The zfcp_reqlist where to remove all entries
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* @list: The list where to move all entries
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*/
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static inline void zfcp_reqlist_move(struct zfcp_reqlist *rl,
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struct list_head *list)
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{
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unsigned int i;
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unsigned long flags;
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spin_lock_irqsave(&rl->lock, flags);
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for (i = 0; i < ZFCP_REQ_LIST_BUCKETS; i++)
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list_splice_init(&rl->buckets[i], list);
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spin_unlock_irqrestore(&rl->lock, flags);
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}
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#endif /* ZFCP_REQLIST_H */
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