1 | /* |
2 | * |
3 | * dvb_ringbuffer.c: ring buffer implementation for the dvb driver |
4 | * |
5 | * Copyright (C) 2003 Oliver Endriss |
6 | * Copyright (C) 2004 Andrew de Quincey |
7 | * |
8 | * based on code originally found in av7110.c & dvb_ci.c: |
9 | * Copyright (C) 1999-2003 Ralph Metzler |
10 | * & Marcus Metzler for convergence integrated media GmbH |
11 | * |
12 | * This program is free software; you can redistribute it and/or |
13 | * modify it under the terms of the GNU Lesser General Public License |
14 | * as published by the Free Software Foundation; either version 2.1 |
15 | * of the License, or (at your option) any later version. |
16 | * |
17 | * This program is distributed in the hope that it will be useful, |
18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
20 | * GNU Lesser General Public License for more details. |
21 | */ |
22 | |
23 | |
24 | |
25 | #include <linux/errno.h> |
26 | #include <linux/kernel.h> |
27 | #include <linux/module.h> |
28 | #include <linux/sched.h> |
29 | #include <linux/string.h> |
30 | #include <linux/uaccess.h> |
31 | |
32 | #include <media/dvb_ringbuffer.h> |
33 | |
34 | #define PKT_READY 0 |
35 | #define PKT_DISPOSED 1 |
36 | |
37 | |
38 | void dvb_ringbuffer_init(struct dvb_ringbuffer *rbuf, void *data, size_t len) |
39 | { |
40 | rbuf->pread=rbuf->pwrite=0; |
41 | rbuf->data=data; |
42 | rbuf->size=len; |
43 | rbuf->error=0; |
44 | |
45 | init_waitqueue_head(&rbuf->queue); |
46 | |
47 | spin_lock_init(&(rbuf->lock)); |
48 | } |
49 | |
50 | |
51 | |
52 | int dvb_ringbuffer_empty(struct dvb_ringbuffer *rbuf) |
53 | { |
54 | /* smp_load_acquire() to load write pointer on reader side |
55 | * this pairs with smp_store_release() in dvb_ringbuffer_write(), |
56 | * dvb_ringbuffer_write_user(), or dvb_ringbuffer_reset() |
57 | * |
58 | * for memory barriers also see Documentation/core-api/circular-buffers.rst |
59 | */ |
60 | return (rbuf->pread == smp_load_acquire(&rbuf->pwrite)); |
61 | } |
62 | |
63 | |
64 | |
65 | ssize_t dvb_ringbuffer_free(struct dvb_ringbuffer *rbuf) |
66 | { |
67 | ssize_t free; |
68 | |
69 | /* READ_ONCE() to load read pointer on writer side |
70 | * this pairs with smp_store_release() in dvb_ringbuffer_read(), |
71 | * dvb_ringbuffer_read_user(), dvb_ringbuffer_flush(), |
72 | * or dvb_ringbuffer_reset() |
73 | */ |
74 | free = READ_ONCE(rbuf->pread) - rbuf->pwrite; |
75 | if (free <= 0) |
76 | free += rbuf->size; |
77 | return free-1; |
78 | } |
79 | |
80 | |
81 | |
82 | ssize_t dvb_ringbuffer_avail(struct dvb_ringbuffer *rbuf) |
83 | { |
84 | ssize_t avail; |
85 | |
86 | /* smp_load_acquire() to load write pointer on reader side |
87 | * this pairs with smp_store_release() in dvb_ringbuffer_write(), |
88 | * dvb_ringbuffer_write_user(), or dvb_ringbuffer_reset() |
89 | */ |
90 | avail = smp_load_acquire(&rbuf->pwrite) - rbuf->pread; |
91 | if (avail < 0) |
92 | avail += rbuf->size; |
93 | return avail; |
94 | } |
95 | |
96 | |
97 | |
98 | void dvb_ringbuffer_flush(struct dvb_ringbuffer *rbuf) |
99 | { |
100 | /* dvb_ringbuffer_flush() counts as read operation |
101 | * smp_load_acquire() to load write pointer |
102 | * smp_store_release() to update read pointer, this ensures that the |
103 | * correct pointer is visible for subsequent dvb_ringbuffer_free() |
104 | * calls on other cpu cores |
105 | */ |
106 | smp_store_release(&rbuf->pread, smp_load_acquire(&rbuf->pwrite)); |
107 | rbuf->error = 0; |
108 | } |
109 | EXPORT_SYMBOL(dvb_ringbuffer_flush); |
110 | |
111 | void dvb_ringbuffer_reset(struct dvb_ringbuffer *rbuf) |
112 | { |
113 | /* dvb_ringbuffer_reset() counts as read and write operation |
114 | * smp_store_release() to update read pointer |
115 | */ |
116 | smp_store_release(&rbuf->pread, 0); |
117 | /* smp_store_release() to update write pointer */ |
118 | smp_store_release(&rbuf->pwrite, 0); |
119 | rbuf->error = 0; |
120 | } |
121 | |
122 | void dvb_ringbuffer_flush_spinlock_wakeup(struct dvb_ringbuffer *rbuf) |
123 | { |
124 | unsigned long flags; |
125 | |
126 | spin_lock_irqsave(&rbuf->lock, flags); |
127 | dvb_ringbuffer_flush(rbuf); |
128 | spin_unlock_irqrestore(lock: &rbuf->lock, flags); |
129 | |
130 | wake_up(&rbuf->queue); |
131 | } |
132 | |
133 | ssize_t dvb_ringbuffer_read_user(struct dvb_ringbuffer *rbuf, u8 __user *buf, size_t len) |
134 | { |
135 | size_t todo = len; |
136 | size_t split; |
137 | |
138 | split = (rbuf->pread + len > rbuf->size) ? rbuf->size - rbuf->pread : 0; |
139 | if (split > 0) { |
140 | if (copy_to_user(to: buf, from: rbuf->data+rbuf->pread, n: split)) |
141 | return -EFAULT; |
142 | buf += split; |
143 | todo -= split; |
144 | /* smp_store_release() for read pointer update to ensure |
145 | * that buf is not overwritten until read is complete, |
146 | * this pairs with READ_ONCE() in dvb_ringbuffer_free() |
147 | */ |
148 | smp_store_release(&rbuf->pread, 0); |
149 | } |
150 | if (copy_to_user(to: buf, from: rbuf->data+rbuf->pread, n: todo)) |
151 | return -EFAULT; |
152 | |
153 | /* smp_store_release() to update read pointer, see above */ |
154 | smp_store_release(&rbuf->pread, (rbuf->pread + todo) % rbuf->size); |
155 | |
156 | return len; |
157 | } |
158 | |
159 | void dvb_ringbuffer_read(struct dvb_ringbuffer *rbuf, u8 *buf, size_t len) |
160 | { |
161 | size_t todo = len; |
162 | size_t split; |
163 | |
164 | split = (rbuf->pread + len > rbuf->size) ? rbuf->size - rbuf->pread : 0; |
165 | if (split > 0) { |
166 | memcpy(buf, rbuf->data+rbuf->pread, split); |
167 | buf += split; |
168 | todo -= split; |
169 | /* smp_store_release() for read pointer update to ensure |
170 | * that buf is not overwritten until read is complete, |
171 | * this pairs with READ_ONCE() in dvb_ringbuffer_free() |
172 | */ |
173 | smp_store_release(&rbuf->pread, 0); |
174 | } |
175 | memcpy(buf, rbuf->data+rbuf->pread, todo); |
176 | |
177 | /* smp_store_release() to update read pointer, see above */ |
178 | smp_store_release(&rbuf->pread, (rbuf->pread + todo) % rbuf->size); |
179 | } |
180 | |
181 | |
182 | ssize_t dvb_ringbuffer_write(struct dvb_ringbuffer *rbuf, const u8 *buf, size_t len) |
183 | { |
184 | size_t todo = len; |
185 | size_t split; |
186 | |
187 | split = (rbuf->pwrite + len > rbuf->size) ? rbuf->size - rbuf->pwrite : 0; |
188 | |
189 | if (split > 0) { |
190 | memcpy(rbuf->data+rbuf->pwrite, buf, split); |
191 | buf += split; |
192 | todo -= split; |
193 | /* smp_store_release() for write pointer update to ensure that |
194 | * written data is visible on other cpu cores before the pointer |
195 | * update, this pairs with smp_load_acquire() in |
196 | * dvb_ringbuffer_empty() or dvb_ringbuffer_avail() |
197 | */ |
198 | smp_store_release(&rbuf->pwrite, 0); |
199 | } |
200 | memcpy(rbuf->data+rbuf->pwrite, buf, todo); |
201 | /* smp_store_release() for write pointer update, see above */ |
202 | smp_store_release(&rbuf->pwrite, (rbuf->pwrite + todo) % rbuf->size); |
203 | |
204 | return len; |
205 | } |
206 | |
207 | ssize_t dvb_ringbuffer_write_user(struct dvb_ringbuffer *rbuf, |
208 | const u8 __user *buf, size_t len) |
209 | { |
210 | int status; |
211 | size_t todo = len; |
212 | size_t split; |
213 | |
214 | split = (rbuf->pwrite + len > rbuf->size) ? rbuf->size - rbuf->pwrite : 0; |
215 | |
216 | if (split > 0) { |
217 | status = copy_from_user(to: rbuf->data+rbuf->pwrite, from: buf, n: split); |
218 | if (status) |
219 | return len - todo; |
220 | buf += split; |
221 | todo -= split; |
222 | /* smp_store_release() for write pointer update to ensure that |
223 | * written data is visible on other cpu cores before the pointer |
224 | * update, this pairs with smp_load_acquire() in |
225 | * dvb_ringbuffer_empty() or dvb_ringbuffer_avail() |
226 | */ |
227 | smp_store_release(&rbuf->pwrite, 0); |
228 | } |
229 | status = copy_from_user(to: rbuf->data+rbuf->pwrite, from: buf, n: todo); |
230 | if (status) |
231 | return len - todo; |
232 | /* smp_store_release() for write pointer update, see above */ |
233 | smp_store_release(&rbuf->pwrite, (rbuf->pwrite + todo) % rbuf->size); |
234 | |
235 | return len; |
236 | } |
237 | |
238 | ssize_t dvb_ringbuffer_pkt_write(struct dvb_ringbuffer *rbuf, u8* buf, size_t len) |
239 | { |
240 | int status; |
241 | ssize_t oldpwrite = rbuf->pwrite; |
242 | |
243 | DVB_RINGBUFFER_WRITE_BYTE(rbuf, len >> 8); |
244 | DVB_RINGBUFFER_WRITE_BYTE(rbuf, len & 0xff); |
245 | DVB_RINGBUFFER_WRITE_BYTE(rbuf, PKT_READY); |
246 | status = dvb_ringbuffer_write(rbuf, buf, len); |
247 | |
248 | if (status < 0) rbuf->pwrite = oldpwrite; |
249 | return status; |
250 | } |
251 | |
252 | ssize_t dvb_ringbuffer_pkt_read_user(struct dvb_ringbuffer *rbuf, size_t idx, |
253 | int offset, u8 __user *buf, size_t len) |
254 | { |
255 | size_t todo; |
256 | size_t split; |
257 | size_t pktlen; |
258 | |
259 | pktlen = rbuf->data[idx] << 8; |
260 | pktlen |= rbuf->data[(idx + 1) % rbuf->size]; |
261 | if (offset > pktlen) return -EINVAL; |
262 | if ((offset + len) > pktlen) len = pktlen - offset; |
263 | |
264 | idx = (idx + DVB_RINGBUFFER_PKTHDRSIZE + offset) % rbuf->size; |
265 | todo = len; |
266 | split = ((idx + len) > rbuf->size) ? rbuf->size - idx : 0; |
267 | if (split > 0) { |
268 | if (copy_to_user(to: buf, from: rbuf->data+idx, n: split)) |
269 | return -EFAULT; |
270 | buf += split; |
271 | todo -= split; |
272 | idx = 0; |
273 | } |
274 | if (copy_to_user(to: buf, from: rbuf->data+idx, n: todo)) |
275 | return -EFAULT; |
276 | |
277 | return len; |
278 | } |
279 | |
280 | ssize_t dvb_ringbuffer_pkt_read(struct dvb_ringbuffer *rbuf, size_t idx, |
281 | int offset, u8* buf, size_t len) |
282 | { |
283 | size_t todo; |
284 | size_t split; |
285 | size_t pktlen; |
286 | |
287 | pktlen = rbuf->data[idx] << 8; |
288 | pktlen |= rbuf->data[(idx + 1) % rbuf->size]; |
289 | if (offset > pktlen) return -EINVAL; |
290 | if ((offset + len) > pktlen) len = pktlen - offset; |
291 | |
292 | idx = (idx + DVB_RINGBUFFER_PKTHDRSIZE + offset) % rbuf->size; |
293 | todo = len; |
294 | split = ((idx + len) > rbuf->size) ? rbuf->size - idx : 0; |
295 | if (split > 0) { |
296 | memcpy(buf, rbuf->data+idx, split); |
297 | buf += split; |
298 | todo -= split; |
299 | idx = 0; |
300 | } |
301 | memcpy(buf, rbuf->data+idx, todo); |
302 | return len; |
303 | } |
304 | |
305 | void dvb_ringbuffer_pkt_dispose(struct dvb_ringbuffer *rbuf, size_t idx) |
306 | { |
307 | size_t pktlen; |
308 | |
309 | rbuf->data[(idx + 2) % rbuf->size] = PKT_DISPOSED; |
310 | |
311 | // clean up disposed packets |
312 | while(dvb_ringbuffer_avail(rbuf) > DVB_RINGBUFFER_PKTHDRSIZE) { |
313 | if (DVB_RINGBUFFER_PEEK(rbuf, 2) == PKT_DISPOSED) { |
314 | pktlen = DVB_RINGBUFFER_PEEK(rbuf, 0) << 8; |
315 | pktlen |= DVB_RINGBUFFER_PEEK(rbuf, 1); |
316 | DVB_RINGBUFFER_SKIP(rbuf, pktlen + DVB_RINGBUFFER_PKTHDRSIZE); |
317 | } else { |
318 | // first packet is not disposed, so we stop cleaning now |
319 | break; |
320 | } |
321 | } |
322 | } |
323 | |
324 | ssize_t dvb_ringbuffer_pkt_next(struct dvb_ringbuffer *rbuf, size_t idx, size_t* pktlen) |
325 | { |
326 | int consumed; |
327 | int curpktlen; |
328 | int curpktstatus; |
329 | |
330 | if (idx == -1) { |
331 | idx = rbuf->pread; |
332 | } else { |
333 | curpktlen = rbuf->data[idx] << 8; |
334 | curpktlen |= rbuf->data[(idx + 1) % rbuf->size]; |
335 | idx = (idx + curpktlen + DVB_RINGBUFFER_PKTHDRSIZE) % rbuf->size; |
336 | } |
337 | |
338 | consumed = (idx - rbuf->pread); |
339 | if (consumed < 0) |
340 | consumed += rbuf->size; |
341 | |
342 | while((dvb_ringbuffer_avail(rbuf) - consumed) > DVB_RINGBUFFER_PKTHDRSIZE) { |
343 | |
344 | curpktlen = rbuf->data[idx] << 8; |
345 | curpktlen |= rbuf->data[(idx + 1) % rbuf->size]; |
346 | curpktstatus = rbuf->data[(idx + 2) % rbuf->size]; |
347 | |
348 | if (curpktstatus == PKT_READY) { |
349 | *pktlen = curpktlen; |
350 | return idx; |
351 | } |
352 | |
353 | consumed += curpktlen + DVB_RINGBUFFER_PKTHDRSIZE; |
354 | idx = (idx + curpktlen + DVB_RINGBUFFER_PKTHDRSIZE) % rbuf->size; |
355 | } |
356 | |
357 | // no packets available |
358 | return -1; |
359 | } |
360 | |
361 | |
362 | |
363 | EXPORT_SYMBOL(dvb_ringbuffer_init); |
364 | EXPORT_SYMBOL(dvb_ringbuffer_empty); |
365 | EXPORT_SYMBOL(dvb_ringbuffer_free); |
366 | EXPORT_SYMBOL(dvb_ringbuffer_avail); |
367 | EXPORT_SYMBOL(dvb_ringbuffer_flush_spinlock_wakeup); |
368 | EXPORT_SYMBOL(dvb_ringbuffer_read_user); |
369 | EXPORT_SYMBOL(dvb_ringbuffer_read); |
370 | EXPORT_SYMBOL(dvb_ringbuffer_write); |
371 | EXPORT_SYMBOL(dvb_ringbuffer_write_user); |
372 | |