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