Commit | Line | Data |
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e82894f8 TZ |
1 | /* |
2 | * Public API and common code for RelayFS. | |
3 | * | |
4 | * See Documentation/filesystems/relayfs.txt for an overview of relayfs. | |
5 | * | |
6 | * Copyright (C) 2002-2005 - Tom Zanussi (zanussi@us.ibm.com), IBM Corp | |
7 | * Copyright (C) 1999-2005 - Karim Yaghmour (karim@opersys.com) | |
8 | * | |
9 | * This file is released under the GPL. | |
10 | */ | |
11 | ||
12 | #include <linux/errno.h> | |
13 | #include <linux/stddef.h> | |
14 | #include <linux/slab.h> | |
15 | #include <linux/module.h> | |
16 | #include <linux/string.h> | |
17 | #include <linux/relayfs_fs.h> | |
18 | #include "relay.h" | |
19 | #include "buffers.h" | |
20 | ||
21 | /** | |
22 | * relay_buf_empty - boolean, is the channel buffer empty? | |
23 | * @buf: channel buffer | |
24 | * | |
25 | * Returns 1 if the buffer is empty, 0 otherwise. | |
26 | */ | |
27 | int relay_buf_empty(struct rchan_buf *buf) | |
28 | { | |
29 | return (buf->subbufs_produced - buf->subbufs_consumed) ? 0 : 1; | |
30 | } | |
31 | ||
32 | /** | |
33 | * relay_buf_full - boolean, is the channel buffer full? | |
34 | * @buf: channel buffer | |
35 | * | |
36 | * Returns 1 if the buffer is full, 0 otherwise. | |
37 | */ | |
38 | int relay_buf_full(struct rchan_buf *buf) | |
39 | { | |
40 | size_t ready = buf->subbufs_produced - buf->subbufs_consumed; | |
41 | return (ready >= buf->chan->n_subbufs) ? 1 : 0; | |
42 | } | |
43 | ||
44 | /* | |
45 | * High-level relayfs kernel API and associated functions. | |
46 | */ | |
47 | ||
48 | /* | |
49 | * rchan_callback implementations defining default channel behavior. Used | |
50 | * in place of corresponding NULL values in client callback struct. | |
51 | */ | |
52 | ||
53 | /* | |
54 | * subbuf_start() default callback. Does nothing. | |
55 | */ | |
56 | static int subbuf_start_default_callback (struct rchan_buf *buf, | |
57 | void *subbuf, | |
58 | void *prev_subbuf, | |
59 | size_t prev_padding) | |
60 | { | |
61 | if (relay_buf_full(buf)) | |
62 | return 0; | |
63 | ||
64 | return 1; | |
65 | } | |
66 | ||
67 | /* | |
68 | * buf_mapped() default callback. Does nothing. | |
69 | */ | |
70 | static void buf_mapped_default_callback(struct rchan_buf *buf, | |
71 | struct file *filp) | |
72 | { | |
73 | } | |
74 | ||
75 | /* | |
76 | * buf_unmapped() default callback. Does nothing. | |
77 | */ | |
78 | static void buf_unmapped_default_callback(struct rchan_buf *buf, | |
79 | struct file *filp) | |
80 | { | |
81 | } | |
82 | ||
08c541a7 TZ |
83 | /* |
84 | * create_buf_file_create() default callback. Creates file to represent buf. | |
85 | */ | |
86 | static struct dentry *create_buf_file_default_callback(const char *filename, | |
87 | struct dentry *parent, | |
88 | int mode, | |
e6c08367 TZ |
89 | struct rchan_buf *buf, |
90 | int *is_global) | |
08c541a7 TZ |
91 | { |
92 | return relayfs_create_file(filename, parent, mode, | |
761da5c8 | 93 | &relay_file_operations, buf); |
08c541a7 TZ |
94 | } |
95 | ||
96 | /* | |
97 | * remove_buf_file() default callback. Removes file representing relay buffer. | |
98 | */ | |
99 | static int remove_buf_file_default_callback(struct dentry *dentry) | |
100 | { | |
101 | return relayfs_remove(dentry); | |
102 | } | |
103 | ||
e82894f8 TZ |
104 | /* relay channel default callbacks */ |
105 | static struct rchan_callbacks default_channel_callbacks = { | |
106 | .subbuf_start = subbuf_start_default_callback, | |
107 | .buf_mapped = buf_mapped_default_callback, | |
108 | .buf_unmapped = buf_unmapped_default_callback, | |
08c541a7 TZ |
109 | .create_buf_file = create_buf_file_default_callback, |
110 | .remove_buf_file = remove_buf_file_default_callback, | |
e82894f8 TZ |
111 | }; |
112 | ||
113 | /** | |
114 | * wakeup_readers - wake up readers waiting on a channel | |
115 | * @private: the channel buffer | |
116 | * | |
117 | * This is the work function used to defer reader waking. The | |
118 | * reason waking is deferred is that calling directly from write | |
119 | * causes problems if you're writing from say the scheduler. | |
120 | */ | |
121 | static void wakeup_readers(void *private) | |
122 | { | |
123 | struct rchan_buf *buf = private; | |
124 | wake_up_interruptible(&buf->read_wait); | |
125 | } | |
126 | ||
127 | /** | |
128 | * __relay_reset - reset a channel buffer | |
129 | * @buf: the channel buffer | |
130 | * @init: 1 if this is a first-time initialization | |
131 | * | |
132 | * See relay_reset for description of effect. | |
133 | */ | |
134 | static inline void __relay_reset(struct rchan_buf *buf, unsigned int init) | |
135 | { | |
136 | size_t i; | |
137 | ||
138 | if (init) { | |
139 | init_waitqueue_head(&buf->read_wait); | |
140 | kref_init(&buf->kref); | |
141 | INIT_WORK(&buf->wake_readers, NULL, NULL); | |
142 | } else { | |
143 | cancel_delayed_work(&buf->wake_readers); | |
144 | flush_scheduled_work(); | |
145 | } | |
146 | ||
147 | buf->subbufs_produced = 0; | |
148 | buf->subbufs_consumed = 0; | |
149 | buf->bytes_consumed = 0; | |
150 | buf->finalized = 0; | |
151 | buf->data = buf->start; | |
152 | buf->offset = 0; | |
153 | ||
154 | for (i = 0; i < buf->chan->n_subbufs; i++) | |
155 | buf->padding[i] = 0; | |
156 | ||
157 | buf->chan->cb->subbuf_start(buf, buf->data, NULL, 0); | |
158 | } | |
159 | ||
160 | /** | |
161 | * relay_reset - reset the channel | |
162 | * @chan: the channel | |
163 | * | |
164 | * This has the effect of erasing all data from all channel buffers | |
165 | * and restarting the channel in its initial state. The buffers | |
166 | * are not freed, so any mappings are still in effect. | |
167 | * | |
168 | * NOTE: Care should be taken that the channel isn't actually | |
169 | * being used by anything when this call is made. | |
170 | */ | |
171 | void relay_reset(struct rchan *chan) | |
172 | { | |
173 | unsigned int i; | |
e6c08367 | 174 | struct rchan_buf *prev = NULL; |
e82894f8 TZ |
175 | |
176 | if (!chan) | |
177 | return; | |
178 | ||
179 | for (i = 0; i < NR_CPUS; i++) { | |
e6c08367 TZ |
180 | if (!chan->buf[i] || chan->buf[i] == prev) |
181 | break; | |
e82894f8 | 182 | __relay_reset(chan->buf[i], 0); |
e6c08367 | 183 | prev = chan->buf[i]; |
e82894f8 TZ |
184 | } |
185 | } | |
186 | ||
187 | /** | |
188 | * relay_open_buf - create a new channel buffer in relayfs | |
189 | * | |
190 | * Internal - used by relay_open(). | |
191 | */ | |
192 | static struct rchan_buf *relay_open_buf(struct rchan *chan, | |
193 | const char *filename, | |
e6c08367 TZ |
194 | struct dentry *parent, |
195 | int *is_global) | |
e82894f8 TZ |
196 | { |
197 | struct rchan_buf *buf; | |
198 | struct dentry *dentry; | |
199 | ||
e6c08367 TZ |
200 | if (*is_global) |
201 | return chan->buf[0]; | |
202 | ||
6625b861 TZ |
203 | buf = relay_create_buf(chan); |
204 | if (!buf) | |
205 | return NULL; | |
206 | ||
e82894f8 | 207 | /* Create file in fs */ |
08c541a7 | 208 | dentry = chan->cb->create_buf_file(filename, parent, S_IRUSR, |
e6c08367 | 209 | buf, is_global); |
6625b861 TZ |
210 | if (!dentry) { |
211 | relay_destroy_buf(buf); | |
e82894f8 | 212 | return NULL; |
6625b861 | 213 | } |
e82894f8 | 214 | |
e82894f8 TZ |
215 | buf->dentry = dentry; |
216 | __relay_reset(buf, 1); | |
217 | ||
218 | return buf; | |
219 | } | |
220 | ||
221 | /** | |
222 | * relay_close_buf - close a channel buffer | |
223 | * @buf: channel buffer | |
224 | * | |
225 | * Marks the buffer finalized and restores the default callbacks. | |
226 | * The channel buffer and channel buffer data structure are then freed | |
227 | * automatically when the last reference is given up. | |
228 | */ | |
229 | static inline void relay_close_buf(struct rchan_buf *buf) | |
230 | { | |
231 | buf->finalized = 1; | |
232 | buf->chan->cb = &default_channel_callbacks; | |
233 | cancel_delayed_work(&buf->wake_readers); | |
234 | flush_scheduled_work(); | |
235 | kref_put(&buf->kref, relay_remove_buf); | |
236 | } | |
237 | ||
238 | static inline void setup_callbacks(struct rchan *chan, | |
239 | struct rchan_callbacks *cb) | |
240 | { | |
241 | if (!cb) { | |
242 | chan->cb = &default_channel_callbacks; | |
243 | return; | |
244 | } | |
245 | ||
246 | if (!cb->subbuf_start) | |
247 | cb->subbuf_start = subbuf_start_default_callback; | |
248 | if (!cb->buf_mapped) | |
249 | cb->buf_mapped = buf_mapped_default_callback; | |
250 | if (!cb->buf_unmapped) | |
251 | cb->buf_unmapped = buf_unmapped_default_callback; | |
08c541a7 TZ |
252 | if (!cb->create_buf_file) |
253 | cb->create_buf_file = create_buf_file_default_callback; | |
254 | if (!cb->remove_buf_file) | |
255 | cb->remove_buf_file = remove_buf_file_default_callback; | |
e82894f8 TZ |
256 | chan->cb = cb; |
257 | } | |
258 | ||
259 | /** | |
260 | * relay_open - create a new relayfs channel | |
261 | * @base_filename: base name of files to create | |
262 | * @parent: dentry of parent directory, NULL for root directory | |
263 | * @subbuf_size: size of sub-buffers | |
264 | * @n_subbufs: number of sub-buffers | |
265 | * @cb: client callback functions | |
266 | * | |
267 | * Returns channel pointer if successful, NULL otherwise. | |
268 | * | |
269 | * Creates a channel buffer for each cpu using the sizes and | |
270 | * attributes specified. The created channel buffer files | |
271 | * will be named base_filename0...base_filenameN-1. File | |
272 | * permissions will be S_IRUSR. | |
273 | */ | |
274 | struct rchan *relay_open(const char *base_filename, | |
275 | struct dentry *parent, | |
276 | size_t subbuf_size, | |
277 | size_t n_subbufs, | |
278 | struct rchan_callbacks *cb) | |
279 | { | |
280 | unsigned int i; | |
281 | struct rchan *chan; | |
282 | char *tmpname; | |
e6c08367 | 283 | int is_global = 0; |
e82894f8 TZ |
284 | |
285 | if (!base_filename) | |
286 | return NULL; | |
287 | ||
288 | if (!(subbuf_size && n_subbufs)) | |
289 | return NULL; | |
290 | ||
291 | chan = kcalloc(1, sizeof(struct rchan), GFP_KERNEL); | |
292 | if (!chan) | |
293 | return NULL; | |
294 | ||
295 | chan->version = RELAYFS_CHANNEL_VERSION; | |
296 | chan->n_subbufs = n_subbufs; | |
297 | chan->subbuf_size = subbuf_size; | |
298 | chan->alloc_size = FIX_SIZE(subbuf_size * n_subbufs); | |
299 | setup_callbacks(chan, cb); | |
300 | kref_init(&chan->kref); | |
301 | ||
302 | tmpname = kmalloc(NAME_MAX + 1, GFP_KERNEL); | |
303 | if (!tmpname) | |
304 | goto free_chan; | |
305 | ||
306 | for_each_online_cpu(i) { | |
307 | sprintf(tmpname, "%s%d", base_filename, i); | |
e6c08367 TZ |
308 | chan->buf[i] = relay_open_buf(chan, tmpname, parent, |
309 | &is_global); | |
e82894f8 TZ |
310 | chan->buf[i]->cpu = i; |
311 | if (!chan->buf[i]) | |
312 | goto free_bufs; | |
313 | } | |
314 | ||
315 | kfree(tmpname); | |
316 | return chan; | |
317 | ||
318 | free_bufs: | |
319 | for (i = 0; i < NR_CPUS; i++) { | |
320 | if (!chan->buf[i]) | |
321 | break; | |
322 | relay_close_buf(chan->buf[i]); | |
e6c08367 TZ |
323 | if (is_global) |
324 | break; | |
e82894f8 TZ |
325 | } |
326 | kfree(tmpname); | |
327 | ||
328 | free_chan: | |
329 | kref_put(&chan->kref, relay_destroy_channel); | |
330 | return NULL; | |
331 | } | |
332 | ||
333 | /** | |
334 | * relay_switch_subbuf - switch to a new sub-buffer | |
335 | * @buf: channel buffer | |
336 | * @length: size of current event | |
337 | * | |
338 | * Returns either the length passed in or 0 if full. | |
339 | ||
340 | * Performs sub-buffer-switch tasks such as invoking callbacks, | |
341 | * updating padding counts, waking up readers, etc. | |
342 | */ | |
343 | size_t relay_switch_subbuf(struct rchan_buf *buf, size_t length) | |
344 | { | |
345 | void *old, *new; | |
346 | size_t old_subbuf, new_subbuf; | |
347 | ||
348 | if (unlikely(length > buf->chan->subbuf_size)) | |
349 | goto toobig; | |
350 | ||
351 | if (buf->offset != buf->chan->subbuf_size + 1) { | |
352 | buf->prev_padding = buf->chan->subbuf_size - buf->offset; | |
353 | old_subbuf = buf->subbufs_produced % buf->chan->n_subbufs; | |
354 | buf->padding[old_subbuf] = buf->prev_padding; | |
355 | buf->subbufs_produced++; | |
356 | if (waitqueue_active(&buf->read_wait)) { | |
357 | PREPARE_WORK(&buf->wake_readers, wakeup_readers, buf); | |
358 | schedule_delayed_work(&buf->wake_readers, 1); | |
359 | } | |
360 | } | |
361 | ||
362 | old = buf->data; | |
363 | new_subbuf = buf->subbufs_produced % buf->chan->n_subbufs; | |
364 | new = buf->start + new_subbuf * buf->chan->subbuf_size; | |
365 | buf->offset = 0; | |
366 | if (!buf->chan->cb->subbuf_start(buf, new, old, buf->prev_padding)) { | |
367 | buf->offset = buf->chan->subbuf_size + 1; | |
368 | return 0; | |
369 | } | |
370 | buf->data = new; | |
371 | buf->padding[new_subbuf] = 0; | |
372 | ||
373 | if (unlikely(length + buf->offset > buf->chan->subbuf_size)) | |
374 | goto toobig; | |
375 | ||
376 | return length; | |
377 | ||
378 | toobig: | |
fd30fc32 | 379 | buf->chan->last_toobig = length; |
e82894f8 TZ |
380 | return 0; |
381 | } | |
382 | ||
383 | /** | |
384 | * relay_subbufs_consumed - update the buffer's sub-buffers-consumed count | |
385 | * @chan: the channel | |
386 | * @cpu: the cpu associated with the channel buffer to update | |
387 | * @subbufs_consumed: number of sub-buffers to add to current buf's count | |
388 | * | |
389 | * Adds to the channel buffer's consumed sub-buffer count. | |
390 | * subbufs_consumed should be the number of sub-buffers newly consumed, | |
391 | * not the total consumed. | |
392 | * | |
393 | * NOTE: kernel clients don't need to call this function if the channel | |
394 | * mode is 'overwrite'. | |
395 | */ | |
396 | void relay_subbufs_consumed(struct rchan *chan, | |
397 | unsigned int cpu, | |
398 | size_t subbufs_consumed) | |
399 | { | |
400 | struct rchan_buf *buf; | |
401 | ||
402 | if (!chan) | |
403 | return; | |
404 | ||
405 | if (cpu >= NR_CPUS || !chan->buf[cpu]) | |
406 | return; | |
407 | ||
408 | buf = chan->buf[cpu]; | |
409 | buf->subbufs_consumed += subbufs_consumed; | |
410 | if (buf->subbufs_consumed > buf->subbufs_produced) | |
411 | buf->subbufs_consumed = buf->subbufs_produced; | |
412 | } | |
413 | ||
414 | /** | |
415 | * relay_destroy_channel - free the channel struct | |
416 | * | |
417 | * Should only be called from kref_put(). | |
418 | */ | |
419 | void relay_destroy_channel(struct kref *kref) | |
420 | { | |
421 | struct rchan *chan = container_of(kref, struct rchan, kref); | |
422 | kfree(chan); | |
423 | } | |
424 | ||
425 | /** | |
426 | * relay_close - close the channel | |
427 | * @chan: the channel | |
428 | * | |
429 | * Closes all channel buffers and frees the channel. | |
430 | */ | |
431 | void relay_close(struct rchan *chan) | |
432 | { | |
433 | unsigned int i; | |
e6c08367 | 434 | struct rchan_buf *prev = NULL; |
e82894f8 TZ |
435 | |
436 | if (!chan) | |
437 | return; | |
438 | ||
439 | for (i = 0; i < NR_CPUS; i++) { | |
e6c08367 TZ |
440 | if (!chan->buf[i] || chan->buf[i] == prev) |
441 | break; | |
e82894f8 | 442 | relay_close_buf(chan->buf[i]); |
e6c08367 | 443 | prev = chan->buf[i]; |
e82894f8 TZ |
444 | } |
445 | ||
fd30fc32 TZ |
446 | if (chan->last_toobig) |
447 | printk(KERN_WARNING "relayfs: one or more items not logged " | |
448 | "[item size (%Zd) > sub-buffer size (%Zd)]\n", | |
449 | chan->last_toobig, chan->subbuf_size); | |
450 | ||
e82894f8 TZ |
451 | kref_put(&chan->kref, relay_destroy_channel); |
452 | } | |
453 | ||
454 | /** | |
455 | * relay_flush - close the channel | |
456 | * @chan: the channel | |
457 | * | |
458 | * Flushes all channel buffers i.e. forces buffer switch. | |
459 | */ | |
460 | void relay_flush(struct rchan *chan) | |
461 | { | |
462 | unsigned int i; | |
e6c08367 | 463 | struct rchan_buf *prev = NULL; |
e82894f8 TZ |
464 | |
465 | if (!chan) | |
466 | return; | |
467 | ||
468 | for (i = 0; i < NR_CPUS; i++) { | |
e6c08367 TZ |
469 | if (!chan->buf[i] || chan->buf[i] == prev) |
470 | break; | |
e82894f8 | 471 | relay_switch_subbuf(chan->buf[i], 0); |
e6c08367 | 472 | prev = chan->buf[i]; |
e82894f8 TZ |
473 | } |
474 | } | |
475 | ||
476 | EXPORT_SYMBOL_GPL(relay_open); | |
477 | EXPORT_SYMBOL_GPL(relay_close); | |
478 | EXPORT_SYMBOL_GPL(relay_flush); | |
479 | EXPORT_SYMBOL_GPL(relay_reset); | |
480 | EXPORT_SYMBOL_GPL(relay_subbufs_consumed); | |
481 | EXPORT_SYMBOL_GPL(relay_switch_subbuf); | |
482 | EXPORT_SYMBOL_GPL(relay_buf_full); |