1 // SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB
2 /* Copyright (c) 2018 Mellanox Technologies */
3
4 #include <linux/jhash.h>
5 #include <linux/slab.h>
6 #include <linux/xarray.h>
7 #include <linux/hashtable.h>
8 #include <linux/refcount.h>
9
10 #include "mapping.h"
11
12 #define MAPPING_GRACE_PERIOD 2000
13
14 static LIST_HEAD(shared_ctx_list);
15 static DEFINE_MUTEX(shared_ctx_lock);
16
17 struct mapping_ctx {
18 struct xarray xarray;
19 DECLARE_HASHTABLE(ht, 8);
20 struct mutex lock; /* Guards hashtable and xarray */
21 unsigned long max_id;
22 size_t data_size;
23 bool delayed_removal;
24 struct delayed_work dwork;
25 struct list_head pending_list;
26 spinlock_t pending_list_lock; /* Guards pending list */
27 u64 id;
28 u8 type;
29 struct list_head list;
30 refcount_t refcount;
31 };
32
33 struct mapping_item {
34 struct rcu_head rcu;
35 struct list_head list;
36 unsigned long timeout;
37 struct hlist_node node;
38 int cnt;
39 u32 id;
40 char data[];
41 };
42
mapping_add(struct mapping_ctx * ctx,void * data,u32 * id)43 int mapping_add(struct mapping_ctx *ctx, void *data, u32 *id)
44 {
45 struct mapping_item *mi;
46 int err = -ENOMEM;
47 u32 hash_key;
48
49 mutex_lock(&ctx->lock);
50
51 hash_key = jhash(data, ctx->data_size, 0);
52 hash_for_each_possible(ctx->ht, mi, node, hash_key) {
53 if (!memcmp(data, mi->data, ctx->data_size))
54 goto attach;
55 }
56
57 mi = kzalloc(sizeof(*mi) + ctx->data_size, GFP_KERNEL);
58 if (!mi)
59 goto err_alloc;
60
61 memcpy(mi->data, data, ctx->data_size);
62 hash_add(ctx->ht, &mi->node, hash_key);
63
64 err = xa_alloc(&ctx->xarray, &mi->id, mi, XA_LIMIT(1, ctx->max_id),
65 GFP_KERNEL);
66 if (err)
67 goto err_assign;
68 attach:
69 ++mi->cnt;
70 *id = mi->id;
71
72 mutex_unlock(&ctx->lock);
73
74 return 0;
75
76 err_assign:
77 hash_del(&mi->node);
78 kfree(mi);
79 err_alloc:
80 mutex_unlock(&ctx->lock);
81
82 return err;
83 }
84
mapping_remove_and_free(struct mapping_ctx * ctx,struct mapping_item * mi)85 static void mapping_remove_and_free(struct mapping_ctx *ctx,
86 struct mapping_item *mi)
87 {
88 xa_erase(&ctx->xarray, mi->id);
89 kfree_rcu(mi, rcu);
90 }
91
mapping_free_item(struct mapping_ctx * ctx,struct mapping_item * mi)92 static void mapping_free_item(struct mapping_ctx *ctx,
93 struct mapping_item *mi)
94 {
95 if (!ctx->delayed_removal) {
96 mapping_remove_and_free(ctx, mi);
97 return;
98 }
99
100 mi->timeout = jiffies + msecs_to_jiffies(MAPPING_GRACE_PERIOD);
101
102 spin_lock(&ctx->pending_list_lock);
103 list_add_tail(&mi->list, &ctx->pending_list);
104 spin_unlock(&ctx->pending_list_lock);
105
106 schedule_delayed_work(&ctx->dwork, MAPPING_GRACE_PERIOD);
107 }
108
mapping_remove(struct mapping_ctx * ctx,u32 id)109 int mapping_remove(struct mapping_ctx *ctx, u32 id)
110 {
111 unsigned long index = id;
112 struct mapping_item *mi;
113 int err = -ENOENT;
114
115 mutex_lock(&ctx->lock);
116 mi = xa_load(&ctx->xarray, index);
117 if (!mi)
118 goto out;
119 err = 0;
120
121 if (--mi->cnt > 0)
122 goto out;
123
124 hash_del(&mi->node);
125 mapping_free_item(ctx, mi);
126 out:
127 mutex_unlock(&ctx->lock);
128
129 return err;
130 }
131
mapping_find(struct mapping_ctx * ctx,u32 id,void * data)132 int mapping_find(struct mapping_ctx *ctx, u32 id, void *data)
133 {
134 unsigned long index = id;
135 struct mapping_item *mi;
136 int err = -ENOENT;
137
138 rcu_read_lock();
139 mi = xa_load(&ctx->xarray, index);
140 if (!mi)
141 goto err_find;
142
143 memcpy(data, mi->data, ctx->data_size);
144 err = 0;
145
146 err_find:
147 rcu_read_unlock();
148 return err;
149 }
150
151 static void
mapping_remove_and_free_list(struct mapping_ctx * ctx,struct list_head * list)152 mapping_remove_and_free_list(struct mapping_ctx *ctx, struct list_head *list)
153 {
154 struct mapping_item *mi;
155
156 list_for_each_entry(mi, list, list)
157 mapping_remove_and_free(ctx, mi);
158 }
159
mapping_work_handler(struct work_struct * work)160 static void mapping_work_handler(struct work_struct *work)
161 {
162 unsigned long min_timeout = 0, now = jiffies;
163 struct mapping_item *mi, *next;
164 LIST_HEAD(pending_items);
165 struct mapping_ctx *ctx;
166
167 ctx = container_of(work, struct mapping_ctx, dwork.work);
168
169 spin_lock(&ctx->pending_list_lock);
170 list_for_each_entry_safe(mi, next, &ctx->pending_list, list) {
171 if (time_after(now, mi->timeout))
172 list_move(&mi->list, &pending_items);
173 else if (!min_timeout ||
174 time_before(mi->timeout, min_timeout))
175 min_timeout = mi->timeout;
176 }
177 spin_unlock(&ctx->pending_list_lock);
178
179 mapping_remove_and_free_list(ctx, &pending_items);
180
181 if (min_timeout)
182 schedule_delayed_work(&ctx->dwork, abs(min_timeout - now));
183 }
184
mapping_flush_work(struct mapping_ctx * ctx)185 static void mapping_flush_work(struct mapping_ctx *ctx)
186 {
187 if (!ctx->delayed_removal)
188 return;
189
190 cancel_delayed_work_sync(&ctx->dwork);
191 mapping_remove_and_free_list(ctx, &ctx->pending_list);
192 }
193
194 struct mapping_ctx *
mapping_create(size_t data_size,u32 max_id,bool delayed_removal)195 mapping_create(size_t data_size, u32 max_id, bool delayed_removal)
196 {
197 struct mapping_ctx *ctx;
198
199 ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
200 if (!ctx)
201 return ERR_PTR(-ENOMEM);
202
203 ctx->max_id = max_id ? max_id : UINT_MAX;
204 ctx->data_size = data_size;
205
206 if (delayed_removal) {
207 INIT_DELAYED_WORK(&ctx->dwork, mapping_work_handler);
208 INIT_LIST_HEAD(&ctx->pending_list);
209 spin_lock_init(&ctx->pending_list_lock);
210 ctx->delayed_removal = true;
211 }
212
213 mutex_init(&ctx->lock);
214 xa_init_flags(&ctx->xarray, XA_FLAGS_ALLOC1);
215
216 refcount_set(&ctx->refcount, 1);
217 INIT_LIST_HEAD(&ctx->list);
218
219 return ctx;
220 }
221
222 struct mapping_ctx *
mapping_create_for_id(u64 id,u8 type,size_t data_size,u32 max_id,bool delayed_removal)223 mapping_create_for_id(u64 id, u8 type, size_t data_size, u32 max_id, bool delayed_removal)
224 {
225 struct mapping_ctx *ctx;
226
227 mutex_lock(&shared_ctx_lock);
228 list_for_each_entry(ctx, &shared_ctx_list, list) {
229 if (ctx->id == id && ctx->type == type) {
230 if (refcount_inc_not_zero(&ctx->refcount))
231 goto unlock;
232 break;
233 }
234 }
235
236 ctx = mapping_create(data_size, max_id, delayed_removal);
237 if (IS_ERR(ctx))
238 goto unlock;
239
240 ctx->id = id;
241 ctx->type = type;
242 list_add(&ctx->list, &shared_ctx_list);
243
244 unlock:
245 mutex_unlock(&shared_ctx_lock);
246 return ctx;
247 }
248
mapping_destroy(struct mapping_ctx * ctx)249 void mapping_destroy(struct mapping_ctx *ctx)
250 {
251 if (!refcount_dec_and_test(&ctx->refcount))
252 return;
253
254 mutex_lock(&shared_ctx_lock);
255 list_del(&ctx->list);
256 mutex_unlock(&shared_ctx_lock);
257
258 mapping_flush_work(ctx);
259 xa_destroy(&ctx->xarray);
260 mutex_destroy(&ctx->lock);
261
262 kfree(ctx);
263 }
264