1181905Sed/*- 2181905Sed * Copyright (c) 2008 Ed Schouten <ed@FreeBSD.org> 3181905Sed * All rights reserved. 4181905Sed * 5181905Sed * Portions of this software were developed under sponsorship from Snow 6181905Sed * B.V., the Netherlands. 7181905Sed * 8181905Sed * Redistribution and use in source and binary forms, with or without 9181905Sed * modification, are permitted provided that the following conditions 10181905Sed * are met: 11181905Sed * 1. Redistributions of source code must retain the above copyright 12181905Sed * notice, this list of conditions and the following disclaimer. 13181905Sed * 2. Redistributions in binary form must reproduce the above copyright 14181905Sed * notice, this list of conditions and the following disclaimer in the 15181905Sed * documentation and/or other materials provided with the distribution. 16181905Sed * 17181905Sed * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 18181905Sed * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19181905Sed * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20181905Sed * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 21181905Sed * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22181905Sed * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23181905Sed * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24181905Sed * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25181905Sed * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26181905Sed * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27181905Sed * SUCH DAMAGE. 28181905Sed */ 29181905Sed 30181905Sed#include <sys/cdefs.h> 31181905Sed__FBSDID("$FreeBSD: stable/11/sys/kern/tty_outq.c 314538 2017-03-02 04:23:53Z ian $"); 32181905Sed 33181905Sed#include <sys/param.h> 34181905Sed#include <sys/kernel.h> 35181905Sed#include <sys/lock.h> 36181905Sed#include <sys/queue.h> 37181905Sed#include <sys/systm.h> 38181905Sed#include <sys/tty.h> 39181905Sed#include <sys/uio.h> 40181905Sed 41181905Sed#include <vm/uma.h> 42181905Sed 43181905Sed/* 44181905Sed * TTY output queue buffering. 45181905Sed * 46181905Sed * The previous design of the TTY layer offered the so-called clists. 47181905Sed * These clists were used for both the input queues and the output 48181905Sed * queue. We don't use certain features on the output side, like quoting 49181905Sed * bits for parity marking and such. This mechanism is similar to the 50181905Sed * old clists, but only contains the features we need to buffer the 51181905Sed * output. 52181905Sed */ 53181905Sed 54181905Sedstruct ttyoutq_block { 55188096Sed struct ttyoutq_block *tob_next; 56188096Sed char tob_data[TTYOUTQ_DATASIZE]; 57181905Sed}; 58181905Sed 59181905Sedstatic uma_zone_t ttyoutq_zone; 60181905Sed 61188096Sed#define TTYOUTQ_INSERT_TAIL(to, tob) do { \ 62188096Sed if (to->to_end == 0) { \ 63188096Sed tob->tob_next = to->to_firstblock; \ 64188096Sed to->to_firstblock = tob; \ 65188096Sed } else { \ 66188096Sed tob->tob_next = to->to_lastblock->tob_next; \ 67188096Sed to->to_lastblock->tob_next = tob; \ 68188096Sed } \ 69188096Sed to->to_nblocks++; \ 70188096Sed} while (0) 71188096Sed 72188096Sed#define TTYOUTQ_REMOVE_HEAD(to) do { \ 73188096Sed to->to_firstblock = to->to_firstblock->tob_next; \ 74188096Sed to->to_nblocks--; \ 75188096Sed} while (0) 76188096Sed 77188096Sed#define TTYOUTQ_RECYCLE(to, tob) do { \ 78188096Sed if (to->to_quota <= to->to_nblocks) \ 79188096Sed uma_zfree(ttyoutq_zone, tob); \ 80188096Sed else \ 81188096Sed TTYOUTQ_INSERT_TAIL(to, tob); \ 82188096Sed} while(0) 83188096Sed 84181905Sedvoid 85181905Sedttyoutq_flush(struct ttyoutq *to) 86181905Sed{ 87181905Sed 88181905Sed to->to_begin = 0; 89181905Sed to->to_end = 0; 90181905Sed} 91181905Sed 92314538Sianint 93181905Sedttyoutq_setsize(struct ttyoutq *to, struct tty *tp, size_t size) 94181905Sed{ 95181905Sed struct ttyoutq_block *tob; 96181905Sed 97182471Sed to->to_quota = howmany(size, TTYOUTQ_DATASIZE); 98181905Sed 99182471Sed while (to->to_quota > to->to_nblocks) { 100181905Sed /* 101181905Sed * List is getting bigger. 102181905Sed * Add new blocks to the tail of the list. 103181905Sed * 104181905Sed * We must unlock the TTY temporarily, because we need 105181905Sed * to allocate memory. This won't be a problem, because 106181905Sed * in the worst case, another thread ends up here, which 107181905Sed * may cause us to allocate too many blocks, but this 108181905Sed * will be caught by the loop below. 109181905Sed */ 110181905Sed tty_unlock(tp); 111181905Sed tob = uma_zalloc(ttyoutq_zone, M_WAITOK); 112181905Sed tty_lock(tp); 113181905Sed 114314538Sian if (tty_gone(tp)) { 115314538Sian uma_zfree(ttyoutq_zone, tob); 116314538Sian return (ENXIO); 117314538Sian } 118314538Sian 119188096Sed TTYOUTQ_INSERT_TAIL(to, tob); 120181905Sed } 121314538Sian return (0); 122182471Sed} 123181905Sed 124182471Sedvoid 125182471Sedttyoutq_free(struct ttyoutq *to) 126182471Sed{ 127182471Sed struct ttyoutq_block *tob; 128223575Sed 129182471Sed ttyoutq_flush(to); 130182471Sed to->to_quota = 0; 131181905Sed 132188096Sed while ((tob = to->to_firstblock) != NULL) { 133188096Sed TTYOUTQ_REMOVE_HEAD(to); 134181905Sed uma_zfree(ttyoutq_zone, tob); 135181905Sed } 136182471Sed 137182471Sed MPASS(to->to_nblocks == 0); 138181905Sed} 139181905Sed 140181905Sedsize_t 141181905Sedttyoutq_read(struct ttyoutq *to, void *buf, size_t len) 142181905Sed{ 143181905Sed char *cbuf = buf; 144181905Sed 145181905Sed while (len > 0) { 146181905Sed struct ttyoutq_block *tob; 147181905Sed size_t cbegin, cend, clen; 148181905Sed 149181905Sed /* See if there still is data. */ 150181905Sed if (to->to_begin == to->to_end) 151181905Sed break; 152188096Sed tob = to->to_firstblock; 153181905Sed if (tob == NULL) 154181905Sed break; 155181905Sed 156181905Sed /* 157181905Sed * The end address should be the lowest of these three: 158181905Sed * - The write pointer 159181905Sed * - The blocksize - we can't read beyond the block 160181905Sed * - The end address if we could perform the full read 161181905Sed */ 162181905Sed cbegin = to->to_begin; 163181905Sed cend = MIN(MIN(to->to_end, to->to_begin + len), 164181905Sed TTYOUTQ_DATASIZE); 165181905Sed clen = cend - cbegin; 166181905Sed 167188096Sed /* Copy the data out of the buffers. */ 168188096Sed memcpy(cbuf, tob->tob_data + cbegin, clen); 169188096Sed cbuf += clen; 170188096Sed len -= clen; 171188096Sed 172188096Sed if (cend == to->to_end) { 173188096Sed /* Read the complete queue. */ 174188096Sed to->to_begin = 0; 175188096Sed to->to_end = 0; 176188096Sed } else if (cend == TTYOUTQ_DATASIZE) { 177181905Sed /* Read the block until the end. */ 178188096Sed TTYOUTQ_REMOVE_HEAD(to); 179181905Sed to->to_begin = 0; 180188096Sed to->to_end -= TTYOUTQ_DATASIZE; 181188096Sed TTYOUTQ_RECYCLE(to, tob); 182181905Sed } else { 183181905Sed /* Read the block partially. */ 184181905Sed to->to_begin += clen; 185181905Sed } 186181905Sed } 187181905Sed 188181905Sed return (cbuf - (char *)buf); 189181905Sed} 190181905Sed 191181905Sed/* 192181905Sed * An optimized version of ttyoutq_read() which can be used in pseudo 193181905Sed * TTY drivers to directly copy data from the outq to userspace, instead 194181905Sed * of buffering it. 195181905Sed * 196181905Sed * We can only copy data directly if we need to read the entire block 197181905Sed * back to the user, because we temporarily remove the block from the 198181905Sed * queue. Otherwise we need to copy it to a temporary buffer first, to 199181905Sed * make sure data remains in the correct order. 200181905Sed */ 201181905Sedint 202181905Sedttyoutq_read_uio(struct ttyoutq *to, struct tty *tp, struct uio *uio) 203181905Sed{ 204181905Sed 205181905Sed while (uio->uio_resid > 0) { 206181905Sed int error; 207181905Sed struct ttyoutq_block *tob; 208181905Sed size_t cbegin, cend, clen; 209181905Sed 210181905Sed /* See if there still is data. */ 211181905Sed if (to->to_begin == to->to_end) 212181905Sed return (0); 213188096Sed tob = to->to_firstblock; 214181905Sed if (tob == NULL) 215181905Sed return (0); 216181905Sed 217181905Sed /* 218181905Sed * The end address should be the lowest of these three: 219181905Sed * - The write pointer 220181905Sed * - The blocksize - we can't read beyond the block 221181905Sed * - The end address if we could perform the full read 222181905Sed */ 223181905Sed cbegin = to->to_begin; 224181905Sed cend = MIN(MIN(to->to_end, to->to_begin + uio->uio_resid), 225181905Sed TTYOUTQ_DATASIZE); 226181905Sed clen = cend - cbegin; 227181905Sed 228181905Sed /* 229181905Sed * We can prevent buffering in some cases: 230181905Sed * - We need to read the block until the end. 231181905Sed * - We don't need to read the block until the end, but 232181905Sed * there is no data beyond it, which allows us to move 233181905Sed * the write pointer to a new block. 234181905Sed */ 235181905Sed if (cend == TTYOUTQ_DATASIZE || cend == to->to_end) { 236181905Sed /* 237181905Sed * Fast path: zero copy. Remove the first block, 238181905Sed * so we can unlock the TTY temporarily. 239181905Sed */ 240188096Sed TTYOUTQ_REMOVE_HEAD(to); 241181905Sed to->to_begin = 0; 242188096Sed if (to->to_end <= TTYOUTQ_DATASIZE) 243181905Sed to->to_end = 0; 244188096Sed else 245181905Sed to->to_end -= TTYOUTQ_DATASIZE; 246181905Sed 247181905Sed /* Temporary unlock and copy the data to userspace. */ 248181905Sed tty_unlock(tp); 249181905Sed error = uiomove(tob->tob_data + cbegin, clen, uio); 250181905Sed tty_lock(tp); 251181905Sed 252181905Sed /* Block can now be readded to the list. */ 253188096Sed TTYOUTQ_RECYCLE(to, tob); 254181905Sed } else { 255181905Sed char ob[TTYOUTQ_DATASIZE - 1]; 256181905Sed 257181905Sed /* 258181905Sed * Slow path: store data in a temporary buffer. 259181905Sed */ 260181905Sed memcpy(ob, tob->tob_data + cbegin, clen); 261181905Sed to->to_begin += clen; 262181905Sed MPASS(to->to_begin < TTYOUTQ_DATASIZE); 263181905Sed 264181905Sed /* Temporary unlock and copy the data to userspace. */ 265181905Sed tty_unlock(tp); 266181905Sed error = uiomove(ob, clen, uio); 267181905Sed tty_lock(tp); 268182471Sed } 269181905Sed 270182471Sed if (error != 0) 271182471Sed return (error); 272181905Sed } 273181905Sed 274181905Sed return (0); 275181905Sed} 276181905Sed 277181905Sedsize_t 278181905Sedttyoutq_write(struct ttyoutq *to, const void *buf, size_t nbytes) 279181905Sed{ 280181905Sed const char *cbuf = buf; 281181905Sed struct ttyoutq_block *tob; 282181905Sed unsigned int boff; 283181905Sed size_t l; 284181905Sed 285181905Sed while (nbytes > 0) { 286181905Sed boff = to->to_end % TTYOUTQ_DATASIZE; 287181905Sed 288181905Sed if (to->to_end == 0) { 289181905Sed /* First time we're being used or drained. */ 290181905Sed MPASS(to->to_begin == 0); 291188096Sed tob = to->to_firstblock; 292181905Sed if (tob == NULL) { 293181905Sed /* Queue has no blocks. */ 294181905Sed break; 295181905Sed } 296188096Sed to->to_lastblock = tob; 297181905Sed } else if (boff == 0) { 298181905Sed /* We reached the end of this block on last write. */ 299188096Sed tob = to->to_lastblock->tob_next; 300181905Sed if (tob == NULL) { 301181905Sed /* We've reached the watermark. */ 302181905Sed break; 303181905Sed } 304181905Sed to->to_lastblock = tob; 305188096Sed } else { 306188096Sed tob = to->to_lastblock; 307181905Sed } 308181905Sed 309181905Sed /* Don't copy more than was requested. */ 310181905Sed l = MIN(nbytes, TTYOUTQ_DATASIZE - boff); 311181905Sed MPASS(l > 0); 312181905Sed memcpy(tob->tob_data + boff, cbuf, l); 313181905Sed 314181905Sed cbuf += l; 315181905Sed nbytes -= l; 316181905Sed to->to_end += l; 317181905Sed } 318181905Sed 319181905Sed return (cbuf - (const char *)buf); 320181905Sed} 321181905Sed 322181905Sedint 323181905Sedttyoutq_write_nofrag(struct ttyoutq *to, const void *buf, size_t nbytes) 324181905Sed{ 325181905Sed size_t ret; 326181905Sed 327181905Sed if (ttyoutq_bytesleft(to) < nbytes) 328181905Sed return (-1); 329181905Sed 330181905Sed /* We should always be able to write it back. */ 331181905Sed ret = ttyoutq_write(to, buf, nbytes); 332181905Sed MPASS(ret == nbytes); 333181905Sed 334181905Sed return (0); 335181905Sed} 336181905Sed 337181905Sedstatic void 338181905Sedttyoutq_startup(void *dummy) 339181905Sed{ 340181905Sed 341181905Sed ttyoutq_zone = uma_zcreate("ttyoutq", sizeof(struct ttyoutq_block), 342181905Sed NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 343181905Sed} 344181905Sed 345181905SedSYSINIT(ttyoutq, SI_SUB_DRIVERS, SI_ORDER_FIRST, ttyoutq_startup, NULL); 346