zfcp_reqlist.h

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/*
 * zfcp device driver
 *
 * Data structure and helper functions for tracking pending FSF
 * requests.
 *
 * Copyright IBM Corp. 2009
 */

#ifndef ZFCP_REQLIST_H
#define ZFCP_REQLIST_H

/* number of hash buckets */
#define ZFCP_REQ_LIST_BUCKETS 128

struct zfcp_reqlist {
    spinlock_t lock;
    struct list_head buckets[ZFCP_REQ_LIST_BUCKETS];
};

static inline int zfcp_reqlist_hash(unsigned long req_id)
{
    return req_id % ZFCP_REQ_LIST_BUCKETS;
}

static inline struct zfcp_reqlist *zfcp_reqlist_alloc(void)
{
    unsigned int i;
    struct zfcp_reqlist *rl;

    rl = kzalloc(sizeof(struct zfcp_reqlist), GFP_KERNEL);
    if (!rl)
        return NULL;

    spin_lock_init(&rl->lock);

    for (i = 0; i < ZFCP_REQ_LIST_BUCKETS; i++)
        INIT_LIST_HEAD(&rl->buckets[i]);

    return rl;
}

static inline int zfcp_reqlist_isempty(struct zfcp_reqlist *rl)
{
    unsigned int i;

    for (i = 0; i < ZFCP_REQ_LIST_BUCKETS; i++)
        if (!list_empty(&rl->buckets[i]))
            return 0;
    return 1;
}

static inline void zfcp_reqlist_free(struct zfcp_reqlist *rl)
{
    /* sanity check */
    BUG_ON(!zfcp_reqlist_isempty(rl));

    kfree(rl);
}

static inline struct zfcp_fsf_req *
_zfcp_reqlist_find(struct zfcp_reqlist *rl, unsigned long req_id)
{
    struct zfcp_fsf_req *req;
    unsigned int i;

    i = zfcp_reqlist_hash(req_id);
    list_for_each_entry(req, &rl->buckets[i], list)
        if (req->req_id == req_id)
            return req;
    return NULL;
}

static inline struct zfcp_fsf_req *
zfcp_reqlist_find(struct zfcp_reqlist *rl, unsigned long req_id)
{
    unsigned long flags;
    struct zfcp_fsf_req *req;

    spin_lock_irqsave(&rl->lock, flags);
    req = _zfcp_reqlist_find(rl, req_id);
    spin_unlock_irqrestore(&rl->lock, flags);

    return req;
}

static inline struct zfcp_fsf_req *
zfcp_reqlist_find_rm(struct zfcp_reqlist *rl, unsigned long req_id)
{
    unsigned long flags;
    struct zfcp_fsf_req *req;

    spin_lock_irqsave(&rl->lock, flags);
    req = _zfcp_reqlist_find(rl, req_id);
    if (req)
        list_del(&req->list);
    spin_unlock_irqrestore(&rl->lock, flags);

    return req;
}

static inline void zfcp_reqlist_add(struct zfcp_reqlist *rl,
                    struct zfcp_fsf_req *req)
{
    unsigned int i;
    unsigned long flags;

    i = zfcp_reqlist_hash(req->req_id);

    spin_lock_irqsave(&rl->lock, flags);
    list_add_tail(&req->list, &rl->buckets[i]);
    spin_unlock_irqrestore(&rl->lock, flags);
}

static inline void zfcp_reqlist_move(struct zfcp_reqlist *rl,
                     struct list_head *list)
{
    unsigned int i;
    unsigned long flags;

    spin_lock_irqsave(&rl->lock, flags);
    for (i = 0; i < ZFCP_REQ_LIST_BUCKETS; i++)
        list_splice_init(&rl->buckets[i], list);
    spin_unlock_irqrestore(&rl->lock, flags);
}

#endif /* ZFCP_REQLIST_H */