1 files changed, 183 insertions, 0 deletions

diff --git a/drivers/s390/scsi/zfcp_reqlist.h b/drivers/s390/scsi/zfcp_reqlist.h
new file mode 100644
index 00000000000..a72d1b730ab
--- /dev/null
+++ b/drivers/s390/scsi/zfcp_reqlist.h
@@ -0,0 +1,183 @@
+/*
+ * zfcp device driver
+ *
+ * Data structure and helper functions for tracking pending FSF
+ * requests.
+ *
+ * Copyright IBM Corporation 2009
+ */
+
+#ifndef ZFCP_REQLIST_H
+#define ZFCP_REQLIST_H
+
+/* number of hash buckets */
+#define ZFCP_REQ_LIST_BUCKETS 128
+
+/**
+ * struct zfcp_reqlist - Container for request list (reqlist)
+ * @lock: Spinlock for protecting the hash list
+ * @list: Array of hashbuckets, each is a list of requests in this bucket
+ */
+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;
+}
+
+/**
+ * zfcp_reqlist_alloc - Allocate and initialize reqlist
+ *
+ * Returns pointer to allocated reqlist on success, or NULL on
+ * allocation failure.
+ */
+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;
+}
+
+/**
+ * zfcp_reqlist_isempty - Check whether the request list empty
+ * @rl: pointer to reqlist
+ *
+ * Returns: 1 if list is empty, 0 if not
+ */
+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;
+}
+
+/**
+ * zfcp_reqlist_free - Free allocated memory for reqlist
+ * @rl: The reqlist where to free memory
+ */
+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;
+}
+
+/**
+ * zfcp_reqlist_find - Lookup FSF request by its request id
+ * @rl: The reqlist where to lookup the FSF request
+ * @req_id: The request id to look for
+ *
+ * Returns a pointer to the FSF request with the specified request id
+ * or NULL if there is no known FSF request with this id.
+ */
+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;
+}
+
+/**
+ * zfcp_reqlist_find_rm - Lookup request by id and remove it from reqlist
+ * @rl: reqlist where to search and remove entry
+ * @req_id: The request id of the request to look for
+ *
+ * This functions tries to find the FSF request with the specified
+ * id and then removes it from the reqlist. The reqlist lock is held
+ * during both steps of the operation.
+ *
+ * Returns: Pointer to the FSF request if the request has been found,
+ * NULL if it has not been found.
+ */
+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;
+}
+
+/**
+ * zfcp_reqlist_add - Add entry to reqlist
+ * @rl: reqlist where to add the entry
+ * @req: The entry to add
+ *
+ * The request id always increases. As an optimization new requests
+ * are added here with list_add_tail at the end of the bucket lists
+ * while old requests are looked up starting at the beginning of the
+ * lists.
+ */
+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);
+}
+
+/**
+ * zfcp_reqlist_move - Move all entries from reqlist to simple list
+ * @rl: The zfcp_reqlist where to remove all entries
+ * @list: The list where to move all entries
+ */
+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 */