ia64/linux-2.6.18-xen.hg

view lib/textsearch.c @ 871:9cbcc9008446

xen/x86: don't initialize cpu_data[]'s apicid field on generic code

Afaict, this is not only redundant with the intialization done in
drivers/xen/core/smpboot.c, but actually results - at least for
secondary CPUs - in the Xen-specific value written to be later
overwritten with whatever the generic code determines (with no
guarantee that the two values are identical).

Signed-off-by: Jan Beulich <jbeulich@novell.com>
author Keir Fraser <keir.fraser@citrix.com>
date Thu May 14 10:09:15 2009 +0100 (2009-05-14)
parents 831230e53067
children
line source
1 /*
2 * lib/textsearch.c Generic text search interface
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version
7 * 2 of the License, or (at your option) any later version.
8 *
9 * Authors: Thomas Graf <tgraf@suug.ch>
10 * Pablo Neira Ayuso <pablo@eurodev.net>
11 *
12 * ==========================================================================
13 *
14 * INTRODUCTION
15 *
16 * The textsearch infrastructure provides text searching facitilies for
17 * both linear and non-linear data. Individual search algorithms are
18 * implemented in modules and chosen by the user.
19 *
20 * ARCHITECTURE
21 *
22 * User
23 * +----------------+
24 * | finish()|<--------------(6)-----------------+
25 * |get_next_block()|<--------------(5)---------------+ |
26 * | | Algorithm | |
27 * | | +------------------------------+
28 * | | | init() find() destroy() |
29 * | | +------------------------------+
30 * | | Core API ^ ^ ^
31 * | | +---------------+ (2) (4) (8)
32 * | (1)|----->| prepare() |---+ | |
33 * | (3)|----->| find()/next() |-----------+ |
34 * | (7)|----->| destroy() |----------------------+
35 * +----------------+ +---------------+
36 *
37 * (1) User configures a search by calling _prepare() specifying the
38 * search parameters such as the pattern and algorithm name.
39 * (2) Core requests the algorithm to allocate and initialize a search
40 * configuration according to the specified parameters.
41 * (3) User starts the search(es) by calling _find() or _next() to
42 * fetch subsequent occurrences. A state variable is provided
43 * to the algorihtm to store persistant variables.
44 * (4) Core eventually resets the search offset and forwards the find()
45 * request to the algorithm.
46 * (5) Algorithm calls get_next_block() provided by the user continously
47 * to fetch the data to be searched in block by block.
48 * (6) Algorithm invokes finish() after the last call to get_next_block
49 * to clean up any leftovers from get_next_block. (Optional)
50 * (7) User destroys the configuration by calling _destroy().
51 * (8) Core notifies the algorithm to destroy algorithm specific
52 * allocations. (Optional)
53 *
54 * USAGE
55 *
56 * Before a search can be performed, a configuration must be created
57 * by calling textsearch_prepare() specyfing the searching algorithm and
58 * the pattern to look for. The returned configuration may then be used
59 * for an arbitary amount of times and even in parallel as long as a
60 * separate struct ts_state variable is provided to every instance.
61 *
62 * The actual search is performed by either calling textsearch_find_-
63 * continuous() for linear data or by providing an own get_next_block()
64 * implementation and calling textsearch_find(). Both functions return
65 * the position of the first occurrence of the patern or UINT_MAX if
66 * no match was found. Subsequent occurences can be found by calling
67 * textsearch_next() regardless of the linearity of the data.
68 *
69 * Once you're done using a configuration it must be given back via
70 * textsearch_destroy.
71 *
72 * EXAMPLE
73 *
74 * int pos;
75 * struct ts_config *conf;
76 * struct ts_state state;
77 * const char *pattern = "chicken";
78 * const char *example = "We dance the funky chicken";
79 *
80 * conf = textsearch_prepare("kmp", pattern, strlen(pattern),
81 * GFP_KERNEL, TS_AUTOLOAD);
82 * if (IS_ERR(conf)) {
83 * err = PTR_ERR(conf);
84 * goto errout;
85 * }
86 *
87 * pos = textsearch_find_continuous(conf, &state, example, strlen(example));
88 * if (pos != UINT_MAX)
89 * panic("Oh my god, dancing chickens at %d\n", pos);
90 *
91 * textsearch_destroy(conf);
92 *
93 * ==========================================================================
94 */
96 #include <linux/module.h>
97 #include <linux/types.h>
98 #include <linux/string.h>
99 #include <linux/init.h>
100 #include <linux/rcupdate.h>
101 #include <linux/err.h>
102 #include <linux/textsearch.h>
104 static LIST_HEAD(ts_ops);
105 static DEFINE_SPINLOCK(ts_mod_lock);
107 static inline struct ts_ops *lookup_ts_algo(const char *name)
108 {
109 struct ts_ops *o;
111 rcu_read_lock();
112 list_for_each_entry_rcu(o, &ts_ops, list) {
113 if (!strcmp(name, o->name)) {
114 if (!try_module_get(o->owner))
115 o = NULL;
116 rcu_read_unlock();
117 return o;
118 }
119 }
120 rcu_read_unlock();
122 return NULL;
123 }
125 /**
126 * textsearch_register - register a textsearch module
127 * @ops: operations lookup table
128 *
129 * This function must be called by textsearch modules to announce
130 * their presence. The specified &@ops must have %name set to a
131 * unique identifier and the callbacks find(), init(), get_pattern(),
132 * and get_pattern_len() must be implemented.
133 *
134 * Returns 0 or -EEXISTS if another module has already registered
135 * with same name.
136 */
137 int textsearch_register(struct ts_ops *ops)
138 {
139 int err = -EEXIST;
140 struct ts_ops *o;
142 if (ops->name == NULL || ops->find == NULL || ops->init == NULL ||
143 ops->get_pattern == NULL || ops->get_pattern_len == NULL)
144 return -EINVAL;
146 spin_lock(&ts_mod_lock);
147 list_for_each_entry(o, &ts_ops, list) {
148 if (!strcmp(ops->name, o->name))
149 goto errout;
150 }
152 list_add_tail_rcu(&ops->list, &ts_ops);
153 err = 0;
154 errout:
155 spin_unlock(&ts_mod_lock);
156 return err;
157 }
159 /**
160 * textsearch_unregister - unregister a textsearch module
161 * @ops: operations lookup table
162 *
163 * This function must be called by textsearch modules to announce
164 * their disappearance for examples when the module gets unloaded.
165 * The &ops parameter must be the same as the one during the
166 * registration.
167 *
168 * Returns 0 on success or -ENOENT if no matching textsearch
169 * registration was found.
170 */
171 int textsearch_unregister(struct ts_ops *ops)
172 {
173 int err = 0;
174 struct ts_ops *o;
176 spin_lock(&ts_mod_lock);
177 list_for_each_entry(o, &ts_ops, list) {
178 if (o == ops) {
179 list_del_rcu(&o->list);
180 goto out;
181 }
182 }
184 err = -ENOENT;
185 out:
186 spin_unlock(&ts_mod_lock);
187 return err;
188 }
190 struct ts_linear_state
191 {
192 unsigned int len;
193 const void *data;
194 };
196 static unsigned int get_linear_data(unsigned int consumed, const u8 **dst,
197 struct ts_config *conf,
198 struct ts_state *state)
199 {
200 struct ts_linear_state *st = (struct ts_linear_state *) state->cb;
202 if (likely(consumed < st->len)) {
203 *dst = st->data + consumed;
204 return st->len - consumed;
205 }
207 return 0;
208 }
210 /**
211 * textsearch_find_continuous - search a pattern in continuous/linear data
212 * @conf: search configuration
213 * @state: search state
214 * @data: data to search in
215 * @len: length of data
216 *
217 * A simplified version of textsearch_find() for continuous/linear data.
218 * Call textsearch_next() to retrieve subsequent matches.
219 *
220 * Returns the position of first occurrence of the pattern or
221 * UINT_MAX if no occurrence was found.
222 */
223 unsigned int textsearch_find_continuous(struct ts_config *conf,
224 struct ts_state *state,
225 const void *data, unsigned int len)
226 {
227 struct ts_linear_state *st = (struct ts_linear_state *) state->cb;
229 conf->get_next_block = get_linear_data;
230 st->data = data;
231 st->len = len;
233 return textsearch_find(conf, state);
234 }
236 /**
237 * textsearch_prepare - Prepare a search
238 * @algo: name of search algorithm
239 * @pattern: pattern data
240 * @len: length of pattern
241 * @gfp_mask: allocation mask
242 * @flags: search flags
243 *
244 * Looks up the search algorithm module and creates a new textsearch
245 * configuration for the specified pattern. Upon completion all
246 * necessary refcnts are held and the configuration must be put back
247 * using textsearch_put() after usage.
248 *
249 * Note: The format of the pattern may not be compatible between
250 * the various search algorithms.
251 *
252 * Returns a new textsearch configuration according to the specified
253 * parameters or a ERR_PTR().
254 */
255 struct ts_config *textsearch_prepare(const char *algo, const void *pattern,
256 unsigned int len, gfp_t gfp_mask, int flags)
257 {
258 int err = -ENOENT;
259 struct ts_config *conf;
260 struct ts_ops *ops;
262 ops = lookup_ts_algo(algo);
263 #ifdef CONFIG_KMOD
264 /*
265 * Why not always autoload you may ask. Some users are
266 * in a situation where requesting a module may deadlock,
267 * especially when the module is located on a NFS mount.
268 */
269 if (ops == NULL && flags & TS_AUTOLOAD) {
270 request_module("ts_%s", algo);
271 ops = lookup_ts_algo(algo);
272 }
273 #endif
275 if (ops == NULL)
276 goto errout;
278 conf = ops->init(pattern, len, gfp_mask);
279 if (IS_ERR(conf)) {
280 err = PTR_ERR(conf);
281 goto errout;
282 }
284 conf->ops = ops;
285 return conf;
287 errout:
288 if (ops)
289 module_put(ops->owner);
291 return ERR_PTR(err);
292 }
294 /**
295 * textsearch_destroy - destroy a search configuration
296 * @conf: search configuration
297 *
298 * Releases all references of the configuration and frees
299 * up the memory.
300 */
301 void textsearch_destroy(struct ts_config *conf)
302 {
303 if (conf->ops) {
304 if (conf->ops->destroy)
305 conf->ops->destroy(conf);
306 module_put(conf->ops->owner);
307 }
309 kfree(conf);
310 }
312 EXPORT_SYMBOL(textsearch_register);
313 EXPORT_SYMBOL(textsearch_unregister);
314 EXPORT_SYMBOL(textsearch_prepare);
315 EXPORT_SYMBOL(textsearch_find_continuous);
316 EXPORT_SYMBOL(textsearch_destroy);