1 /* 2 * Copyright (C) 2002 - 2008 Jeff Dike (jdike@{addtoit,linux.intel}.com) 3 * Licensed under the GPL 4 */ 5 6 #include <unistd.h> 7 #include <errno.h> 8 #include <fcntl.h> 9 #include <poll.h> 10 #include <pty.h> 11 #include <sched.h> 12 #include <signal.h> 13 #include <string.h> 14 #include "kern_constants.h" 15 #include "kern_util.h" 16 #include "init.h" 17 #include "os.h" 18 #include "process.h" 19 #include "sigio.h" 20 #include "um_malloc.h" 21 #include "user.h" 22 23 /* 24 * Protected by sigio_lock(), also used by sigio_cleanup, which is an 25 * exitcall. 26 */ 27 static int write_sigio_pid = -1; 28 static unsigned long write_sigio_stack; 29 30 /* 31 * These arrays are initialized before the sigio thread is started, and 32 * the descriptors closed after it is killed. So, it can't see them change. 33 * On the UML side, they are changed under the sigio_lock. 34 */ 35 #define SIGIO_FDS_INIT {-1, -1} 36 37 static int write_sigio_fds[2] = SIGIO_FDS_INIT; 38 static int sigio_private[2] = SIGIO_FDS_INIT; 39 40 struct pollfds { 41 struct pollfd *poll; 42 int size; 43 int used; 44 }; 45 46 /* 47 * Protected by sigio_lock(). Used by the sigio thread, but the UML thread 48 * synchronizes with it. 49 */ 50 static struct pollfds current_poll; 51 static struct pollfds next_poll; 52 static struct pollfds all_sigio_fds; 53 54 static int write_sigio_thread(void *unused) 55 { 56 struct pollfds *fds, tmp; 57 struct pollfd *p; 58 int i, n, respond_fd; 59 char c; 60 61 signal(SIGWINCH, SIG_IGN); 62 fds = ¤t_poll; 63 while (1) { 64 n = poll(fds->poll, fds->used, -1); 65 if (n < 0) { 66 if (errno == EINTR) 67 continue; 68 printk(UM_KERN_ERR "write_sigio_thread : poll returned " 69 "%d, errno = %d\n", n, errno); 70 } 71 for (i = 0; i < fds->used; i++) { 72 p = &fds->poll[i]; 73 if (p->revents == 0) 74 continue; 75 if (p->fd == sigio_private[1]) { 76 CATCH_EINTR(n = read(sigio_private[1], &c, 77 sizeof(c))); 78 if (n != sizeof(c)) 79 printk(UM_KERN_ERR 80 "write_sigio_thread : " 81 "read on socket failed, " 82 "err = %d\n", errno); 83 tmp = current_poll; 84 current_poll = next_poll; 85 next_poll = tmp; 86 respond_fd = sigio_private[1]; 87 } 88 else { 89 respond_fd = write_sigio_fds[1]; 90 fds->used--; 91 memmove(&fds->poll[i], &fds->poll[i + 1], 92 (fds->used - i) * sizeof(*fds->poll)); 93 } 94 95 CATCH_EINTR(n = write(respond_fd, &c, sizeof(c))); 96 if (n != sizeof(c)) 97 printk(UM_KERN_ERR "write_sigio_thread : " 98 "write on socket failed, err = %d\n", 99 errno); 100 } 101 } 102 103 return 0; 104 } 105 106 static int need_poll(struct pollfds *polls, int n) 107 { 108 struct pollfd *new; 109 110 if (n <= polls->size) 111 return 0; 112 113 new = uml_kmalloc(n * sizeof(struct pollfd), UM_GFP_ATOMIC); 114 if (new == NULL) { 115 printk(UM_KERN_ERR "need_poll : failed to allocate new " 116 "pollfds\n"); 117 return -ENOMEM; 118 } 119 120 memcpy(new, polls->poll, polls->used * sizeof(struct pollfd)); 121 kfree(polls->poll); 122 123 polls->poll = new; 124 polls->size = n; 125 return 0; 126 } 127 128 /* 129 * Must be called with sigio_lock held, because it's needed by the marked 130 * critical section. 131 */ 132 static void update_thread(void) 133 { 134 unsigned long flags; 135 int n; 136 char c; 137 138 flags = set_signals(0); 139 CATCH_EINTR(n = write(sigio_private[0], &c, sizeof(c))); 140 if (n != sizeof(c)) { 141 printk(UM_KERN_ERR "update_thread : write failed, err = %d\n", 142 errno); 143 goto fail; 144 } 145 146 CATCH_EINTR(n = read(sigio_private[0], &c, sizeof(c))); 147 if (n != sizeof(c)) { 148 printk(UM_KERN_ERR "update_thread : read failed, err = %d\n", 149 errno); 150 goto fail; 151 } 152 153 set_signals(flags); 154 return; 155 fail: 156 /* Critical section start */ 157 if (write_sigio_pid != -1) { 158 os_kill_process(write_sigio_pid, 1); 159 free_stack(write_sigio_stack, 0); 160 } 161 write_sigio_pid = -1; 162 close(sigio_private[0]); 163 close(sigio_private[1]); 164 close(write_sigio_fds[0]); 165 close(write_sigio_fds[1]); 166 /* Critical section end */ 167 set_signals(flags); 168 } 169 170 int add_sigio_fd(int fd) 171 { 172 struct pollfd *p; 173 int err = 0, i, n; 174 175 sigio_lock(); 176 for (i = 0; i < all_sigio_fds.used; i++) { 177 if (all_sigio_fds.poll[i].fd == fd) 178 break; 179 } 180 if (i == all_sigio_fds.used) 181 goto out; 182 183 p = &all_sigio_fds.poll[i]; 184 185 for (i = 0; i < current_poll.used; i++) { 186 if (current_poll.poll[i].fd == fd) 187 goto out; 188 } 189 190 n = current_poll.used; 191 err = need_poll(&next_poll, n + 1); 192 if (err) 193 goto out; 194 195 memcpy(next_poll.poll, current_poll.poll, 196 current_poll.used * sizeof(struct pollfd)); 197 next_poll.poll[n] = *p; 198 next_poll.used = n + 1; 199 update_thread(); 200 out: 201 sigio_unlock(); 202 return err; 203 } 204 205 int ignore_sigio_fd(int fd) 206 { 207 struct pollfd *p; 208 int err = 0, i, n = 0; 209 210 /* 211 * This is called from exitcalls elsewhere in UML - if 212 * sigio_cleanup has already run, then update_thread will hang 213 * or fail because the thread is no longer running. 214 */ 215 if (write_sigio_pid == -1) 216 return -EIO; 217 218 sigio_lock(); 219 for (i = 0; i < current_poll.used; i++) { 220 if (current_poll.poll[i].fd == fd) 221 break; 222 } 223 if (i == current_poll.used) 224 goto out; 225 226 err = need_poll(&next_poll, current_poll.used - 1); 227 if (err) 228 goto out; 229 230 for (i = 0; i < current_poll.used; i++) { 231 p = ¤t_poll.poll[i]; 232 if (p->fd != fd) 233 next_poll.poll[n++] = *p; 234 } 235 next_poll.used = current_poll.used - 1; 236 237 update_thread(); 238 out: 239 sigio_unlock(); 240 return err; 241 } 242 243 static struct pollfd *setup_initial_poll(int fd) 244 { 245 struct pollfd *p; 246 247 p = uml_kmalloc(sizeof(struct pollfd), UM_GFP_KERNEL); 248 if (p == NULL) { 249 printk(UM_KERN_ERR "setup_initial_poll : failed to allocate " 250 "poll\n"); 251 return NULL; 252 } 253 *p = ((struct pollfd) { .fd = fd, 254 .events = POLLIN, 255 .revents = 0 }); 256 return p; 257 } 258 259 static void write_sigio_workaround(void) 260 { 261 struct pollfd *p; 262 int err; 263 int l_write_sigio_fds[2]; 264 int l_sigio_private[2]; 265 int l_write_sigio_pid; 266 267 /* We call this *tons* of times - and most ones we must just fail. */ 268 sigio_lock(); 269 l_write_sigio_pid = write_sigio_pid; 270 sigio_unlock(); 271 272 if (l_write_sigio_pid != -1) 273 return; 274 275 err = os_pipe(l_write_sigio_fds, 1, 1); 276 if (err < 0) { 277 printk(UM_KERN_ERR "write_sigio_workaround - os_pipe 1 failed, " 278 "err = %d\n", -err); 279 return; 280 } 281 err = os_pipe(l_sigio_private, 1, 1); 282 if (err < 0) { 283 printk(UM_KERN_ERR "write_sigio_workaround - os_pipe 2 failed, " 284 "err = %d\n", -err); 285 goto out_close1; 286 } 287 288 p = setup_initial_poll(l_sigio_private[1]); 289 if (!p) 290 goto out_close2; 291 292 sigio_lock(); 293 294 /* 295 * Did we race? Don't try to optimize this, please, it's not so likely 296 * to happen, and no more than once at the boot. 297 */ 298 if (write_sigio_pid != -1) 299 goto out_free; 300 301 current_poll = ((struct pollfds) { .poll = p, 302 .used = 1, 303 .size = 1 }); 304 305 if (write_sigio_irq(l_write_sigio_fds[0])) 306 goto out_clear_poll; 307 308 memcpy(write_sigio_fds, l_write_sigio_fds, sizeof(l_write_sigio_fds)); 309 memcpy(sigio_private, l_sigio_private, sizeof(l_sigio_private)); 310 311 write_sigio_pid = run_helper_thread(write_sigio_thread, NULL, 312 CLONE_FILES | CLONE_VM, 313 &write_sigio_stack); 314 315 if (write_sigio_pid < 0) 316 goto out_clear; 317 318 sigio_unlock(); 319 return; 320 321 out_clear: 322 write_sigio_pid = -1; 323 write_sigio_fds[0] = -1; 324 write_sigio_fds[1] = -1; 325 sigio_private[0] = -1; 326 sigio_private[1] = -1; 327 out_clear_poll: 328 current_poll = ((struct pollfds) { .poll = NULL, 329 .size = 0, 330 .used = 0 }); 331 out_free: 332 sigio_unlock(); 333 kfree(p); 334 out_close2: 335 close(l_sigio_private[0]); 336 close(l_sigio_private[1]); 337 out_close1: 338 close(l_write_sigio_fds[0]); 339 close(l_write_sigio_fds[1]); 340 } 341 342 void sigio_broken(int fd, int read) 343 { 344 int err; 345 346 write_sigio_workaround(); 347 348 sigio_lock(); 349 err = need_poll(&all_sigio_fds, all_sigio_fds.used + 1); 350 if (err) { 351 printk(UM_KERN_ERR "maybe_sigio_broken - failed to add pollfd " 352 "for descriptor %d\n", fd); 353 goto out; 354 } 355 356 all_sigio_fds.poll[all_sigio_fds.used++] = 357 ((struct pollfd) { .fd = fd, 358 .events = read ? POLLIN : POLLOUT, 359 .revents = 0 }); 360 out: 361 sigio_unlock(); 362 } 363 364 /* Changed during early boot */ 365 static int pty_output_sigio; 366 static int pty_close_sigio; 367 368 void maybe_sigio_broken(int fd, int read) 369 { 370 if (!isatty(fd)) 371 return; 372 373 if ((read || pty_output_sigio) && (!read || pty_close_sigio)) 374 return; 375 376 sigio_broken(fd, read); 377 } 378 379 static void sigio_cleanup(void) 380 { 381 if (write_sigio_pid == -1) 382 return; 383 384 os_kill_process(write_sigio_pid, 1); 385 free_stack(write_sigio_stack, 0); 386 write_sigio_pid = -1; 387 } 388 389 __uml_exitcall(sigio_cleanup); 390 391 /* Used as a flag during SIGIO testing early in boot */ 392 static int got_sigio; 393 394 static void __init handler(int sig) 395 { 396 got_sigio = 1; 397 } 398 399 struct openpty_arg { 400 int master; 401 int slave; 402 int err; 403 }; 404 405 static void openpty_cb(void *arg) 406 { 407 struct openpty_arg *info = arg; 408 409 info->err = 0; 410 if (openpty(&info->master, &info->slave, NULL, NULL, NULL)) 411 info->err = -errno; 412 } 413 414 static int async_pty(int master, int slave) 415 { 416 int flags; 417 418 flags = fcntl(master, F_GETFL); 419 if (flags < 0) 420 return -errno; 421 422 if ((fcntl(master, F_SETFL, flags | O_NONBLOCK | O_ASYNC) < 0) || 423 (fcntl(master, F_SETOWN, os_getpid()) < 0)) 424 return -errno; 425 426 if ((fcntl(slave, F_SETFL, flags | O_NONBLOCK) < 0)) 427 return -errno; 428 429 return 0; 430 } 431 432 static void __init check_one_sigio(void (*proc)(int, int)) 433 { 434 struct sigaction old, new; 435 struct openpty_arg pty = { .master = -1, .slave = -1 }; 436 int master, slave, err; 437 438 initial_thread_cb(openpty_cb, &pty); 439 if (pty.err) { 440 printk(UM_KERN_ERR "check_one_sigio failed, errno = %d\n", 441 -pty.err); 442 return; 443 } 444 445 master = pty.master; 446 slave = pty.slave; 447 448 if ((master == -1) || (slave == -1)) { 449 printk(UM_KERN_ERR "check_one_sigio failed to allocate a " 450 "pty\n"); 451 return; 452 } 453 454 /* Not now, but complain so we now where we failed. */ 455 err = raw(master); 456 if (err < 0) { 457 printk(UM_KERN_ERR "check_one_sigio : raw failed, errno = %d\n", 458 -err); 459 return; 460 } 461 462 err = async_pty(master, slave); 463 if (err < 0) { 464 printk(UM_KERN_ERR "check_one_sigio : sigio_async failed, " 465 "err = %d\n", -err); 466 return; 467 } 468 469 if (sigaction(SIGIO, NULL, &old) < 0) { 470 printk(UM_KERN_ERR "check_one_sigio : sigaction 1 failed, " 471 "errno = %d\n", errno); 472 return; 473 } 474 475 new = old; 476 new.sa_handler = handler; 477 if (sigaction(SIGIO, &new, NULL) < 0) { 478 printk(UM_KERN_ERR "check_one_sigio : sigaction 2 failed, " 479 "errno = %d\n", errno); 480 return; 481 } 482 483 got_sigio = 0; 484 (*proc)(master, slave); 485 486 close(master); 487 close(slave); 488 489 if (sigaction(SIGIO, &old, NULL) < 0) 490 printk(UM_KERN_ERR "check_one_sigio : sigaction 3 failed, " 491 "errno = %d\n", errno); 492 } 493 494 static void tty_output(int master, int slave) 495 { 496 int n; 497 char buf[512]; 498 499 printk(UM_KERN_INFO "Checking that host ptys support output SIGIO..."); 500 501 memset(buf, 0, sizeof(buf)); 502 503 while (write(master, buf, sizeof(buf)) > 0) ; 504 if (errno != EAGAIN) 505 printk(UM_KERN_ERR "tty_output : write failed, errno = %d\n", 506 errno); 507 while (((n = read(slave, buf, sizeof(buf))) > 0) && 508 !({ barrier(); got_sigio; })) 509 ; 510 511 if (got_sigio) { 512 printk(UM_KERN_CONT "Yes\n"); 513 pty_output_sigio = 1; 514 } else if (n == -EAGAIN) 515 printk(UM_KERN_CONT "No, enabling workaround\n"); 516 else 517 printk(UM_KERN_CONT "tty_output : read failed, err = %d\n", n); 518 } 519 520 static void tty_close(int master, int slave) 521 { 522 printk(UM_KERN_INFO "Checking that host ptys support SIGIO on " 523 "close..."); 524 525 close(slave); 526 if (got_sigio) { 527 printk(UM_KERN_CONT "Yes\n"); 528 pty_close_sigio = 1; 529 } else 530 printk(UM_KERN_CONT "No, enabling workaround\n"); 531 } 532 533 static void __init check_sigio(void) 534 { 535 if ((access("/dev/ptmx", R_OK) < 0) && 536 (access("/dev/ptyp0", R_OK) < 0)) { 537 printk(UM_KERN_WARNING "No pseudo-terminals available - " 538 "skipping pty SIGIO check\n"); 539 return; 540 } 541 check_one_sigio(tty_output); 542 check_one_sigio(tty_close); 543 } 544 545 /* Here because it only does the SIGIO testing for now */ 546 void __init os_check_bugs(void) 547 { 548 check_sigio(); 549 } 550