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 void 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 TTYOUTQ_INSERT_TAIL(to, tob); 115 } 116 } 117 118 void 119 ttyoutq_free(struct ttyoutq *to) 120 { 121 struct ttyoutq_block *tob; 122 123 ttyoutq_flush(to); 124 to->to_quota = 0; 125 126 while ((tob = to->to_firstblock) != NULL) { 127 TTYOUTQ_REMOVE_HEAD(to); 128 uma_zfree(ttyoutq_zone, tob); 129 } 130 131 MPASS(to->to_nblocks == 0); 132 } 133 134 size_t 135 ttyoutq_read(struct ttyoutq *to, void *buf, size_t len) 136 { 137 char *cbuf = buf; 138 139 while (len > 0) { 140 struct ttyoutq_block *tob; 141 size_t cbegin, cend, clen; 142 143 /* See if there still is data. */ 144 if (to->to_begin == to->to_end) 145 break; 146 tob = to->to_firstblock; 147 if (tob == NULL) 148 break; 149 150 /* 151 * The end address should be the lowest of these three: 152 * - The write pointer 153 * - The blocksize - we can't read beyond the block 154 * - The end address if we could perform the full read 155 */ 156 cbegin = to->to_begin; 157 cend = MIN(MIN(to->to_end, to->to_begin + len), 158 TTYOUTQ_DATASIZE); 159 clen = cend - cbegin; 160 161 /* Copy the data out of the buffers. */ 162 memcpy(cbuf, tob->tob_data + cbegin, clen); 163 cbuf += clen; 164 len -= clen; 165 166 if (cend == to->to_end) { 167 /* Read the complete queue. */ 168 to->to_begin = 0; 169 to->to_end = 0; 170 } else if (cend == TTYOUTQ_DATASIZE) { 171 /* Read the block until the end. */ 172 TTYOUTQ_REMOVE_HEAD(to); 173 to->to_begin = 0; 174 to->to_end -= TTYOUTQ_DATASIZE; 175 TTYOUTQ_RECYCLE(to, tob); 176 } else { 177 /* Read the block partially. */ 178 to->to_begin += clen; 179 } 180 } 181 182 return (cbuf - (char *)buf); 183 } 184 185 /* 186 * An optimized version of ttyoutq_read() which can be used in pseudo 187 * TTY drivers to directly copy data from the outq to userspace, instead 188 * of buffering it. 189 * 190 * We can only copy data directly if we need to read the entire block 191 * back to the user, because we temporarily remove the block from the 192 * queue. Otherwise we need to copy it to a temporary buffer first, to 193 * make sure data remains in the correct order. 194 */ 195 int 196 ttyoutq_read_uio(struct ttyoutq *to, struct tty *tp, struct uio *uio) 197 { 198 199 while (uio->uio_resid > 0) { 200 int error; 201 struct ttyoutq_block *tob; 202 size_t cbegin, cend, clen; 203 204 /* See if there still is data. */ 205 if (to->to_begin == to->to_end) 206 return (0); 207 tob = to->to_firstblock; 208 if (tob == NULL) 209 return (0); 210 211 /* 212 * The end address should be the lowest of these three: 213 * - The write pointer 214 * - The blocksize - we can't read beyond the block 215 * - The end address if we could perform the full read 216 */ 217 cbegin = to->to_begin; 218 cend = MIN(MIN(to->to_end, to->to_begin + uio->uio_resid), 219 TTYOUTQ_DATASIZE); 220 clen = cend - cbegin; 221 222 /* 223 * We can prevent buffering in some cases: 224 * - We need to read the block until the end. 225 * - We don't need to read the block until the end, but 226 * there is no data beyond it, which allows us to move 227 * the write pointer to a new block. 228 */ 229 if (cend == TTYOUTQ_DATASIZE || cend == to->to_end) { 230 /* 231 * Fast path: zero copy. Remove the first block, 232 * so we can unlock the TTY temporarily. 233 */ 234 TTYOUTQ_REMOVE_HEAD(to); 235 to->to_begin = 0; 236 if (to->to_end <= TTYOUTQ_DATASIZE) 237 to->to_end = 0; 238 else 239 to->to_end -= TTYOUTQ_DATASIZE; 240 241 /* Temporary unlock and copy the data to userspace. */ 242 tty_unlock(tp); 243 error = uiomove(tob->tob_data + cbegin, clen, uio); 244 tty_lock(tp); 245 246 /* Block can now be readded to the list. */ 247 TTYOUTQ_RECYCLE(to, tob); 248 } else { 249 char ob[TTYOUTQ_DATASIZE - 1]; 250 251 /* 252 * Slow path: store data in a temporary buffer. 253 */ 254 memcpy(ob, tob->tob_data + cbegin, clen); 255 to->to_begin += clen; 256 MPASS(to->to_begin < TTYOUTQ_DATASIZE); 257 258 /* Temporary unlock and copy the data to userspace. */ 259 tty_unlock(tp); 260 error = uiomove(ob, clen, uio); 261 tty_lock(tp); 262 } 263 264 if (error != 0) 265 return (error); 266 } 267 268 return (0); 269 } 270 271 size_t 272 ttyoutq_write(struct ttyoutq *to, const void *buf, size_t nbytes) 273 { 274 const char *cbuf = buf; 275 struct ttyoutq_block *tob; 276 unsigned int boff; 277 size_t l; 278 279 while (nbytes > 0) { 280 boff = to->to_end % TTYOUTQ_DATASIZE; 281 282 if (to->to_end == 0) { 283 /* First time we're being used or drained. */ 284 MPASS(to->to_begin == 0); 285 tob = to->to_firstblock; 286 if (tob == NULL) { 287 /* Queue has no blocks. */ 288 break; 289 } 290 to->to_lastblock = tob; 291 } else if (boff == 0) { 292 /* We reached the end of this block on last write. */ 293 tob = to->to_lastblock->tob_next; 294 if (tob == NULL) { 295 /* We've reached the watermark. */ 296 break; 297 } 298 to->to_lastblock = tob; 299 } else { 300 tob = to->to_lastblock; 301 } 302 303 /* Don't copy more than was requested. */ 304 l = MIN(nbytes, TTYOUTQ_DATASIZE - boff); 305 MPASS(l > 0); 306 memcpy(tob->tob_data + boff, cbuf, l); 307 308 cbuf += l; 309 nbytes -= l; 310 to->to_end += l; 311 } 312 313 return (cbuf - (const char *)buf); 314 } 315 316 int 317 ttyoutq_write_nofrag(struct ttyoutq *to, const void *buf, size_t nbytes) 318 { 319 size_t ret; 320 321 if (ttyoutq_bytesleft(to) < nbytes) 322 return (-1); 323 324 /* We should always be able to write it back. */ 325 ret = ttyoutq_write(to, buf, nbytes); 326 MPASS(ret == nbytes); 327 328 return (0); 329 } 330 331 static void 332 ttyoutq_startup(void *dummy) 333 { 334 335 ttyoutq_zone = uma_zcreate("ttyoutq", sizeof(struct ttyoutq_block), 336 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 337 } 338 339 SYSINIT(ttyoutq, SI_SUB_DRIVERS, SI_ORDER_FIRST, ttyoutq_startup, NULL); 340