1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 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/param.h> 33 #include <sys/kernel.h> 34 #include <sys/lock.h> 35 #include <sys/queue.h> 36 #include <sys/systm.h> 37 #include <sys/tty.h> 38 #include <sys/uio.h> 39 40 #include <vm/uma.h> 41 42 /* 43 * TTY output queue buffering. 44 * 45 * The previous design of the TTY layer offered the so-called clists. 46 * These clists were used for both the input queues and the output 47 * queue. We don't use certain features on the output side, like quoting 48 * bits for parity marking and such. This mechanism is similar to the 49 * old clists, but only contains the features we need to buffer the 50 * output. 51 */ 52 53 struct ttyoutq_block { 54 struct ttyoutq_block *tob_next; 55 char tob_data[TTYOUTQ_DATASIZE]; 56 }; 57 58 static uma_zone_t ttyoutq_zone; 59 60 #define TTYOUTQ_INSERT_TAIL(to, tob) do { \ 61 if (to->to_end == 0) { \ 62 tob->tob_next = to->to_firstblock; \ 63 to->to_firstblock = tob; \ 64 } else { \ 65 tob->tob_next = to->to_lastblock->tob_next; \ 66 to->to_lastblock->tob_next = tob; \ 67 } \ 68 to->to_nblocks++; \ 69 } while (0) 70 71 #define TTYOUTQ_REMOVE_HEAD(to) do { \ 72 to->to_firstblock = to->to_firstblock->tob_next; \ 73 to->to_nblocks--; \ 74 } while (0) 75 76 #define TTYOUTQ_RECYCLE(to, tob) do { \ 77 if (to->to_quota <= to->to_nblocks) \ 78 uma_zfree(ttyoutq_zone, tob); \ 79 else \ 80 TTYOUTQ_INSERT_TAIL(to, tob); \ 81 } while (0) 82 83 void 84 ttyoutq_flush(struct ttyoutq *to) 85 { 86 87 to->to_begin = 0; 88 to->to_end = 0; 89 } 90 91 int 92 ttyoutq_setsize(struct ttyoutq *to, struct tty *tp, size_t size) 93 { 94 struct ttyoutq_block *tob; 95 96 to->to_quota = howmany(size, TTYOUTQ_DATASIZE); 97 98 while (to->to_quota > to->to_nblocks) { 99 /* 100 * List is getting bigger. 101 * Add new blocks to the tail of the list. 102 * 103 * We must unlock the TTY temporarily, because we need 104 * to allocate memory. This won't be a problem, because 105 * in the worst case, another thread ends up here, which 106 * may cause us to allocate too many blocks, but this 107 * will be caught by the loop below. 108 */ 109 tty_unlock(tp); 110 tob = uma_zalloc(ttyoutq_zone, M_WAITOK); 111 tty_lock(tp); 112 113 if (tty_gone(tp)) { 114 uma_zfree(ttyoutq_zone, tob); 115 return (ENXIO); 116 } 117 118 TTYOUTQ_INSERT_TAIL(to, tob); 119 } 120 return (0); 121 } 122 123 void 124 ttyoutq_free(struct ttyoutq *to) 125 { 126 struct ttyoutq_block *tob; 127 128 ttyoutq_flush(to); 129 to->to_quota = 0; 130 131 while ((tob = to->to_firstblock) != NULL) { 132 TTYOUTQ_REMOVE_HEAD(to); 133 uma_zfree(ttyoutq_zone, tob); 134 } 135 136 MPASS(to->to_nblocks == 0); 137 } 138 139 size_t 140 ttyoutq_read(struct ttyoutq *to, void *buf, size_t len) 141 { 142 char *cbuf = buf; 143 144 while (len > 0) { 145 struct ttyoutq_block *tob; 146 size_t cbegin, cend, clen; 147 148 /* See if there still is data. */ 149 if (to->to_begin == to->to_end) 150 break; 151 tob = to->to_firstblock; 152 if (tob == NULL) 153 break; 154 155 /* 156 * The end address should be the lowest of these three: 157 * - The write pointer 158 * - The blocksize - we can't read beyond the block 159 * - The end address if we could perform the full read 160 */ 161 cbegin = to->to_begin; 162 cend = MIN(MIN(to->to_end, to->to_begin + len), 163 TTYOUTQ_DATASIZE); 164 clen = cend - cbegin; 165 166 /* Copy the data out of the buffers. */ 167 memcpy(cbuf, tob->tob_data + cbegin, clen); 168 cbuf += clen; 169 len -= clen; 170 171 if (cend == to->to_end) { 172 /* Read the complete queue. */ 173 to->to_begin = 0; 174 to->to_end = 0; 175 } else if (cend == TTYOUTQ_DATASIZE) { 176 /* Read the block until the end. */ 177 TTYOUTQ_REMOVE_HEAD(to); 178 to->to_begin = 0; 179 to->to_end -= TTYOUTQ_DATASIZE; 180 TTYOUTQ_RECYCLE(to, tob); 181 } else { 182 /* Read the block partially. */ 183 to->to_begin += clen; 184 } 185 } 186 187 return (cbuf - (char *)buf); 188 } 189 190 /* 191 * An optimized version of ttyoutq_read() which can be used in pseudo 192 * TTY drivers to directly copy data from the outq to userspace, instead 193 * of buffering it. 194 * 195 * We can only copy data directly if we need to read the entire block 196 * back to the user, because we temporarily remove the block from the 197 * queue. Otherwise we need to copy it to a temporary buffer first, to 198 * make sure data remains in the correct order. 199 */ 200 int 201 ttyoutq_read_uio(struct ttyoutq *to, struct tty *tp, struct uio *uio) 202 { 203 204 while (uio->uio_resid > 0) { 205 int error; 206 struct ttyoutq_block *tob; 207 size_t cbegin, cend, clen; 208 209 /* See if there still is data. */ 210 if (to->to_begin == to->to_end) 211 return (0); 212 tob = to->to_firstblock; 213 if (tob == NULL) 214 return (0); 215 216 /* 217 * The end address should be the lowest of these three: 218 * - The write pointer 219 * - The blocksize - we can't read beyond the block 220 * - The end address if we could perform the full read 221 */ 222 cbegin = to->to_begin; 223 cend = MIN(MIN(to->to_end, to->to_begin + uio->uio_resid), 224 TTYOUTQ_DATASIZE); 225 clen = cend - cbegin; 226 227 /* 228 * We can prevent buffering in some cases: 229 * - We need to read the block until the end. 230 * - We don't need to read the block until the end, but 231 * there is no data beyond it, which allows us to move 232 * the write pointer to a new block. 233 */ 234 if (cend == TTYOUTQ_DATASIZE || cend == to->to_end) { 235 /* 236 * Fast path: zero copy. Remove the first block, 237 * so we can unlock the TTY temporarily. 238 */ 239 TTYOUTQ_REMOVE_HEAD(to); 240 to->to_begin = 0; 241 if (to->to_end <= TTYOUTQ_DATASIZE) 242 to->to_end = 0; 243 else 244 to->to_end -= TTYOUTQ_DATASIZE; 245 246 /* Temporary unlock and copy the data to userspace. */ 247 tty_unlock(tp); 248 error = uiomove(tob->tob_data + cbegin, clen, uio); 249 tty_lock(tp); 250 251 /* Block can now be readded to the list. */ 252 TTYOUTQ_RECYCLE(to, tob); 253 } else { 254 char ob[TTYOUTQ_DATASIZE - 1]; 255 256 /* 257 * Slow path: store data in a temporary buffer. 258 */ 259 memcpy(ob, tob->tob_data + cbegin, clen); 260 to->to_begin += clen; 261 MPASS(to->to_begin < TTYOUTQ_DATASIZE); 262 263 /* Temporary unlock and copy the data to userspace. */ 264 tty_unlock(tp); 265 error = uiomove(ob, clen, uio); 266 tty_lock(tp); 267 } 268 269 if (error != 0) 270 return (error); 271 } 272 273 return (0); 274 } 275 276 size_t 277 ttyoutq_write(struct ttyoutq *to, const void *buf, size_t nbytes) 278 { 279 const char *cbuf = buf; 280 struct ttyoutq_block *tob; 281 unsigned int boff; 282 size_t l; 283 284 while (nbytes > 0) { 285 boff = to->to_end % TTYOUTQ_DATASIZE; 286 287 if (to->to_end == 0) { 288 /* First time we're being used or drained. */ 289 MPASS(to->to_begin == 0); 290 tob = to->to_firstblock; 291 if (tob == NULL) { 292 /* Queue has no blocks. */ 293 break; 294 } 295 to->to_lastblock = tob; 296 } else if (boff == 0) { 297 /* We reached the end of this block on last write. */ 298 tob = to->to_lastblock->tob_next; 299 if (tob == NULL) { 300 /* We've reached the watermark. */ 301 break; 302 } 303 to->to_lastblock = tob; 304 } else { 305 tob = to->to_lastblock; 306 } 307 308 /* Don't copy more than was requested. */ 309 l = MIN(nbytes, TTYOUTQ_DATASIZE - boff); 310 MPASS(l > 0); 311 memcpy(tob->tob_data + boff, cbuf, l); 312 313 cbuf += l; 314 nbytes -= l; 315 to->to_end += l; 316 } 317 318 return (cbuf - (const char *)buf); 319 } 320 321 int 322 ttyoutq_write_nofrag(struct ttyoutq *to, const void *buf, size_t nbytes) 323 { 324 size_t ret __unused; 325 326 if (ttyoutq_bytesleft(to) < nbytes) 327 return (-1); 328 329 /* We should always be able to write it back. */ 330 ret = ttyoutq_write(to, buf, nbytes); 331 MPASS(ret == nbytes); 332 333 return (0); 334 } 335 336 static void 337 ttyoutq_startup(void *dummy) 338 { 339 340 ttyoutq_zone = uma_zcreate("ttyoutq", sizeof(struct ttyoutq_block), 341 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 342 } 343 344 SYSINIT(ttyoutq, SI_SUB_DRIVERS, SI_ORDER_FIRST, ttyoutq_startup, NULL); 345