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