1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3 * zfcp device driver
4 *
5 * Data structure and helper functions for tracking pending FSF
6 * requests.
7 *
8 * Copyright IBM Corp. 2009, 2016
9 */
10
11 #ifndef ZFCP_REQLIST_H
12 #define ZFCP_REQLIST_H
13
14 /* number of hash buckets */
15 #define ZFCP_REQ_LIST_BUCKETS 128
16
17 /**
18 * struct zfcp_reqlist - Container for request list (reqlist)
19 * @lock: Spinlock for protecting the hash list
20 * @buckets: Array of hashbuckets, each is a list of requests in this bucket
21 */
22 struct zfcp_reqlist {
23 spinlock_t lock;
24 struct list_head buckets[ZFCP_REQ_LIST_BUCKETS];
25 };
26
zfcp_reqlist_hash(unsigned long req_id)27 static inline int zfcp_reqlist_hash(unsigned long req_id)
28 {
29 return req_id % ZFCP_REQ_LIST_BUCKETS;
30 }
31
32 /**
33 * zfcp_reqlist_alloc - Allocate and initialize reqlist
34 *
35 * Returns pointer to allocated reqlist on success, or NULL on
36 * allocation failure.
37 */
zfcp_reqlist_alloc(void)38 static inline struct zfcp_reqlist *zfcp_reqlist_alloc(void)
39 {
40 unsigned int i;
41 struct zfcp_reqlist *rl;
42
43 rl = kzalloc(sizeof(struct zfcp_reqlist), GFP_KERNEL);
44 if (!rl)
45 return NULL;
46
47 spin_lock_init(&rl->lock);
48
49 for (i = 0; i < ZFCP_REQ_LIST_BUCKETS; i++)
50 INIT_LIST_HEAD(&rl->buckets[i]);
51
52 return rl;
53 }
54
55 /**
56 * zfcp_reqlist_isempty - Check whether the request list empty
57 * @rl: pointer to reqlist
58 *
59 * Returns: 1 if list is empty, 0 if not
60 */
zfcp_reqlist_isempty(struct zfcp_reqlist * rl)61 static inline int zfcp_reqlist_isempty(struct zfcp_reqlist *rl)
62 {
63 unsigned int i;
64
65 for (i = 0; i < ZFCP_REQ_LIST_BUCKETS; i++)
66 if (!list_empty(&rl->buckets[i]))
67 return 0;
68 return 1;
69 }
70
71 /**
72 * zfcp_reqlist_free - Free allocated memory for reqlist
73 * @rl: The reqlist where to free memory
74 */
zfcp_reqlist_free(struct zfcp_reqlist * rl)75 static inline void zfcp_reqlist_free(struct zfcp_reqlist *rl)
76 {
77 /* sanity check */
78 BUG_ON(!zfcp_reqlist_isempty(rl));
79
80 kfree(rl);
81 }
82
83 static inline struct zfcp_fsf_req *
_zfcp_reqlist_find(struct zfcp_reqlist * rl,unsigned long req_id)84 _zfcp_reqlist_find(struct zfcp_reqlist *rl, unsigned long req_id)
85 {
86 struct zfcp_fsf_req *req;
87 unsigned int i;
88
89 i = zfcp_reqlist_hash(req_id);
90 list_for_each_entry(req, &rl->buckets[i], list)
91 if (req->req_id == req_id)
92 return req;
93 return NULL;
94 }
95
96 /**
97 * zfcp_reqlist_find - Lookup FSF request by its request id
98 * @rl: The reqlist where to lookup the FSF request
99 * @req_id: The request id to look for
100 *
101 * Returns a pointer to the FSF request with the specified request id
102 * or NULL if there is no known FSF request with this id.
103 */
104 static inline struct zfcp_fsf_req *
zfcp_reqlist_find(struct zfcp_reqlist * rl,unsigned long req_id)105 zfcp_reqlist_find(struct zfcp_reqlist *rl, unsigned long req_id)
106 {
107 unsigned long flags;
108 struct zfcp_fsf_req *req;
109
110 spin_lock_irqsave(&rl->lock, flags);
111 req = _zfcp_reqlist_find(rl, req_id);
112 spin_unlock_irqrestore(&rl->lock, flags);
113
114 return req;
115 }
116
117 /**
118 * zfcp_reqlist_find_rm - Lookup request by id and remove it from reqlist
119 * @rl: reqlist where to search and remove entry
120 * @req_id: The request id of the request to look for
121 *
122 * This functions tries to find the FSF request with the specified
123 * id and then removes it from the reqlist. The reqlist lock is held
124 * during both steps of the operation.
125 *
126 * Returns: Pointer to the FSF request if the request has been found,
127 * NULL if it has not been found.
128 */
129 static inline struct zfcp_fsf_req *
zfcp_reqlist_find_rm(struct zfcp_reqlist * rl,unsigned long req_id)130 zfcp_reqlist_find_rm(struct zfcp_reqlist *rl, unsigned long req_id)
131 {
132 unsigned long flags;
133 struct zfcp_fsf_req *req;
134
135 spin_lock_irqsave(&rl->lock, flags);
136 req = _zfcp_reqlist_find(rl, req_id);
137 if (req)
138 list_del(&req->list);
139 spin_unlock_irqrestore(&rl->lock, flags);
140
141 return req;
142 }
143
144 /**
145 * zfcp_reqlist_add - Add entry to reqlist
146 * @rl: reqlist where to add the entry
147 * @req: The entry to add
148 *
149 * The request id always increases. As an optimization new requests
150 * are added here with list_add_tail at the end of the bucket lists
151 * while old requests are looked up starting at the beginning of the
152 * lists.
153 */
zfcp_reqlist_add(struct zfcp_reqlist * rl,struct zfcp_fsf_req * req)154 static inline void zfcp_reqlist_add(struct zfcp_reqlist *rl,
155 struct zfcp_fsf_req *req)
156 {
157 unsigned int i;
158 unsigned long flags;
159
160 i = zfcp_reqlist_hash(req->req_id);
161
162 spin_lock_irqsave(&rl->lock, flags);
163 list_add_tail(&req->list, &rl->buckets[i]);
164 spin_unlock_irqrestore(&rl->lock, flags);
165 }
166
167 /**
168 * zfcp_reqlist_move - Move all entries from reqlist to simple list
169 * @rl: The zfcp_reqlist where to remove all entries
170 * @list: The list where to move all entries
171 */
zfcp_reqlist_move(struct zfcp_reqlist * rl,struct list_head * list)172 static inline void zfcp_reqlist_move(struct zfcp_reqlist *rl,
173 struct list_head *list)
174 {
175 unsigned int i;
176 unsigned long flags;
177
178 spin_lock_irqsave(&rl->lock, flags);
179 for (i = 0; i < ZFCP_REQ_LIST_BUCKETS; i++)
180 list_splice_init(&rl->buckets[i], list);
181 spin_unlock_irqrestore(&rl->lock, flags);
182 }
183
184 /**
185 * zfcp_reqlist_apply_for_all() - apply a function to every request.
186 * @rl: the requestlist that contains the target requests.
187 * @f: the function to apply to each request; the first parameter of the
188 * function will be the target-request; the second parameter is the same
189 * pointer as given with the argument @data.
190 * @data: freely chosen argument; passed through to @f as second parameter.
191 *
192 * Uses :c:macro:`list_for_each_entry` to iterate over the lists in the hash-
193 * table (not a 'safe' variant, so don't modify the list).
194 *
195 * Holds @rl->lock over the entire request-iteration.
196 */
197 static inline void
zfcp_reqlist_apply_for_all(struct zfcp_reqlist * rl,void (* f)(struct zfcp_fsf_req *,void *),void * data)198 zfcp_reqlist_apply_for_all(struct zfcp_reqlist *rl,
199 void (*f)(struct zfcp_fsf_req *, void *), void *data)
200 {
201 struct zfcp_fsf_req *req;
202 unsigned long flags;
203 unsigned int i;
204
205 spin_lock_irqsave(&rl->lock, flags);
206 for (i = 0; i < ZFCP_REQ_LIST_BUCKETS; i++)
207 list_for_each_entry(req, &rl->buckets[i], list)
208 f(req, data);
209 spin_unlock_irqrestore(&rl->lock, flags);
210 }
211
212 #endif /* ZFCP_REQLIST_H */
213