1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2008 Ed Schouten <ed@FreeBSD.org> 5 * All rights reserved. 6 * 7 * Portions of this software were developed under sponsorship from Snow 8 * B.V., the Netherlands. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 #include <sys/cdefs.h> 33 __FBSDID("$FreeBSD$"); 34 35 #include <sys/param.h> 36 #include <sys/kernel.h> 37 #include <sys/lock.h> 38 #include <sys/queue.h> 39 #include <sys/systm.h> 40 #include <sys/tty.h> 41 #include <sys/uio.h> 42 43 #include <vm/uma.h> 44 45 /* 46 * TTY output queue buffering. 47 * 48 * The previous design of the TTY layer offered the so-called clists. 49 * These clists were used for both the input queues and the output 50 * queue. We don't use certain features on the output side, like quoting 51 * bits for parity marking and such. This mechanism is similar to the 52 * old clists, but only contains the features we need to buffer the 53 * output. 54 */ 55 56 struct ttyoutq_block { 57 struct ttyoutq_block *tob_next; 58 char tob_data[TTYOUTQ_DATASIZE]; 59 }; 60 61 static uma_zone_t ttyoutq_zone; 62 63 #define TTYOUTQ_INSERT_TAIL(to, tob) do { \ 64 if (to->to_end == 0) { \ 65 tob->tob_next = to->to_firstblock; \ 66 to->to_firstblock = tob; \ 67 } else { \ 68 tob->tob_next = to->to_lastblock->tob_next; \ 69 to->to_lastblock->tob_next = tob; \ 70 } \ 71 to->to_nblocks++; \ 72 } while (0) 73 74 #define TTYOUTQ_REMOVE_HEAD(to) do { \ 75 to->to_firstblock = to->to_firstblock->tob_next; \ 76 to->to_nblocks--; \ 77 } while (0) 78 79 #define TTYOUTQ_RECYCLE(to, tob) do { \ 80 if (to->to_quota <= to->to_nblocks) \ 81 uma_zfree(ttyoutq_zone, tob); \ 82 else \ 83 TTYOUTQ_INSERT_TAIL(to, tob); \ 84 } while (0) 85 86 void 87 ttyoutq_flush(struct ttyoutq *to) 88 { 89 90 to->to_begin = 0; 91 to->to_end = 0; 92 } 93 94 int 95 ttyoutq_setsize(struct ttyoutq *to, struct tty *tp, size_t size) 96 { 97 struct ttyoutq_block *tob; 98 99 to->to_quota = howmany(size, TTYOUTQ_DATASIZE); 100 101 while (to->to_quota > to->to_nblocks) { 102 /* 103 * List is getting bigger. 104 * Add new blocks to the tail of the list. 105 * 106 * We must unlock the TTY temporarily, because we need 107 * to allocate memory. This won't be a problem, because 108 * in the worst case, another thread ends up here, which 109 * may cause us to allocate too many blocks, but this 110 * will be caught by the loop below. 111 */ 112 tty_unlock(tp); 113 tob = uma_zalloc(ttyoutq_zone, M_WAITOK); 114 tty_lock(tp); 115 116 if (tty_gone(tp)) { 117 uma_zfree(ttyoutq_zone, tob); 118 return (ENXIO); 119 } 120 121 TTYOUTQ_INSERT_TAIL(to, tob); 122 } 123 return (0); 124 } 125 126 void 127 ttyoutq_free(struct ttyoutq *to) 128 { 129 struct ttyoutq_block *tob; 130 131 ttyoutq_flush(to); 132 to->to_quota = 0; 133 134 while ((tob = to->to_firstblock) != NULL) { 135 TTYOUTQ_REMOVE_HEAD(to); 136 uma_zfree(ttyoutq_zone, tob); 137 } 138 139 MPASS(to->to_nblocks == 0); 140 } 141 142 size_t 143 ttyoutq_read(struct ttyoutq *to, void *buf, size_t len) 144 { 145 char *cbuf = buf; 146 147 while (len > 0) { 148 struct ttyoutq_block *tob; 149 size_t cbegin, cend, clen; 150 151 /* See if there still is data. */ 152 if (to->to_begin == to->to_end) 153 break; 154 tob = to->to_firstblock; 155 if (tob == NULL) 156 break; 157 158 /* 159 * The end address should be the lowest of these three: 160 * - The write pointer 161 * - The blocksize - we can't read beyond the block 162 * - The end address if we could perform the full read 163 */ 164 cbegin = to->to_begin; 165 cend = MIN(MIN(to->to_end, to->to_begin + len), 166 TTYOUTQ_DATASIZE); 167 clen = cend - cbegin; 168 169 /* Copy the data out of the buffers. */ 170 memcpy(cbuf, tob->tob_data + cbegin, clen); 171 cbuf += clen; 172 len -= clen; 173 174 if (cend == to->to_end) { 175 /* Read the complete queue. */ 176 to->to_begin = 0; 177 to->to_end = 0; 178 } else if (cend == TTYOUTQ_DATASIZE) { 179 /* Read the block until the end. */ 180 TTYOUTQ_REMOVE_HEAD(to); 181 to->to_begin = 0; 182 to->to_end -= TTYOUTQ_DATASIZE; 183 TTYOUTQ_RECYCLE(to, tob); 184 } else { 185 /* Read the block partially. */ 186 to->to_begin += clen; 187 } 188 } 189 190 return (cbuf - (char *)buf); 191 } 192 193 /* 194 * An optimized version of ttyoutq_read() which can be used in pseudo 195 * TTY drivers to directly copy data from the outq to userspace, instead 196 * of buffering it. 197 * 198 * We can only copy data directly if we need to read the entire block 199 * back to the user, because we temporarily remove the block from the 200 * queue. Otherwise we need to copy it to a temporary buffer first, to 201 * make sure data remains in the correct order. 202 */ 203 int 204 ttyoutq_read_uio(struct ttyoutq *to, struct tty *tp, struct uio *uio) 205 { 206 207 while (uio->uio_resid > 0) { 208 int error; 209 struct ttyoutq_block *tob; 210 size_t cbegin, cend, clen; 211 212 /* See if there still is data. */ 213 if (to->to_begin == to->to_end) 214 return (0); 215 tob = to->to_firstblock; 216 if (tob == NULL) 217 return (0); 218 219 /* 220 * The end address should be the lowest of these three: 221 * - The write pointer 222 * - The blocksize - we can't read beyond the block 223 * - The end address if we could perform the full read 224 */ 225 cbegin = to->to_begin; 226 cend = MIN(MIN(to->to_end, to->to_begin + uio->uio_resid), 227 TTYOUTQ_DATASIZE); 228 clen = cend - cbegin; 229 230 /* 231 * We can prevent buffering in some cases: 232 * - We need to read the block until the end. 233 * - We don't need to read the block until the end, but 234 * there is no data beyond it, which allows us to move 235 * the write pointer to a new block. 236 */ 237 if (cend == TTYOUTQ_DATASIZE || cend == to->to_end) { 238 /* 239 * Fast path: zero copy. Remove the first block, 240 * so we can unlock the TTY temporarily. 241 */ 242 TTYOUTQ_REMOVE_HEAD(to); 243 to->to_begin = 0; 244 if (to->to_end <= TTYOUTQ_DATASIZE) 245 to->to_end = 0; 246 else 247 to->to_end -= TTYOUTQ_DATASIZE; 248 249 /* Temporary unlock and copy the data to userspace. */ 250 tty_unlock(tp); 251 error = uiomove(tob->tob_data + cbegin, clen, uio); 252 tty_lock(tp); 253 254 /* Block can now be readded to the list. */ 255 TTYOUTQ_RECYCLE(to, tob); 256 } else { 257 char ob[TTYOUTQ_DATASIZE - 1]; 258 259 /* 260 * Slow path: store data in a temporary buffer. 261 */ 262 memcpy(ob, tob->tob_data + cbegin, clen); 263 to->to_begin += clen; 264 MPASS(to->to_begin < TTYOUTQ_DATASIZE); 265 266 /* Temporary unlock and copy the data to userspace. */ 267 tty_unlock(tp); 268 error = uiomove(ob, clen, uio); 269 tty_lock(tp); 270 } 271 272 if (error != 0) 273 return (error); 274 } 275 276 return (0); 277 } 278 279 size_t 280 ttyoutq_write(struct ttyoutq *to, const void *buf, size_t nbytes) 281 { 282 const char *cbuf = buf; 283 struct ttyoutq_block *tob; 284 unsigned int boff; 285 size_t l; 286 287 while (nbytes > 0) { 288 boff = to->to_end % TTYOUTQ_DATASIZE; 289 290 if (to->to_end == 0) { 291 /* First time we're being used or drained. */ 292 MPASS(to->to_begin == 0); 293 tob = to->to_firstblock; 294 if (tob == NULL) { 295 /* Queue has no blocks. */ 296 break; 297 } 298 to->to_lastblock = tob; 299 } else if (boff == 0) { 300 /* We reached the end of this block on last write. */ 301 tob = to->to_lastblock->tob_next; 302 if (tob == NULL) { 303 /* We've reached the watermark. */ 304 break; 305 } 306 to->to_lastblock = tob; 307 } else { 308 tob = to->to_lastblock; 309 } 310 311 /* Don't copy more than was requested. */ 312 l = MIN(nbytes, TTYOUTQ_DATASIZE - boff); 313 MPASS(l > 0); 314 memcpy(tob->tob_data + boff, cbuf, l); 315 316 cbuf += l; 317 nbytes -= l; 318 to->to_end += l; 319 } 320 321 return (cbuf - (const char *)buf); 322 } 323 324 int 325 ttyoutq_write_nofrag(struct ttyoutq *to, const void *buf, size_t nbytes) 326 { 327 size_t ret __unused; 328 329 if (ttyoutq_bytesleft(to) < nbytes) 330 return (-1); 331 332 /* We should always be able to write it back. */ 333 ret = ttyoutq_write(to, buf, nbytes); 334 MPASS(ret == nbytes); 335 336 return (0); 337 } 338 339 static void 340 ttyoutq_startup(void *dummy) 341 { 342 343 ttyoutq_zone = uma_zcreate("ttyoutq", sizeof(struct ttyoutq_block), 344 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 345 } 346 347 SYSINIT(ttyoutq, SI_SUB_DRIVERS, SI_ORDER_FIRST, ttyoutq_startup, NULL); 348