arch/um/kernel/sigio_user.c

   1 /*
   2  * Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
   3  * Licensed under the GPL
   4  */
   5
   6 #include <unistd.h>
   7 #include <stdlib.h>
   8 #include <termios.h>
   9 #include <pty.h>
  10 #include <signal.h>
  11 #include <errno.h>
  12 #include <string.h>
  13 #include <sched.h>
  14 #include <sys/socket.h>
  15 #include <sys/poll.h>
  16 #include "init.h"
  17 #include "user.h"
  18 #include "kern_util.h"
  19 #include "user_util.h"
  20 #include "sigio.h"
  21 #include "helper.h"
  22 #include "os.h"
  23
  24 /* Changed during early boot */
  25 int pty_output_sigio = 0;
  26 int pty_close_sigio = 0;
  27
  28 /* Used as a flag during SIGIO testing early in boot */
  29 static volatile int got_sigio = 0;
  30
  31 void __init handler(int sig)
  32 {
  33         got_sigio = 1;
  34 }
  35
  36 struct openpty_arg {
  37         int master;
  38         int slave;
  39         int err;
  40 };
  41
  42 static void openpty_cb(void *arg)
  43 {
  44         struct openpty_arg *info = arg;
  45
  46         info->err = 0;
  47         if(openpty(&info->master, &info->slave, NULL, NULL, NULL))
  48                 info->err = -errno;
  49 }
  50
  51 void __init check_one_sigio(void (*proc)(int, int))
  52 {
  53         struct sigaction old, new;
  54         struct openpty_arg pty = { .master = -1, .slave = -1 };
  55         int master, slave, err;
  56
  57         initial_thread_cb(openpty_cb, &pty);
  58         if(pty.err){
  59                 printk("openpty failed, errno = %d\n", -pty.err);
  60                 return;
  61         }
  62
  63         master = pty.master;
  64         slave = pty.slave;
  65
  66         if((master == -1) || (slave == -1)){
  67                 printk("openpty failed to allocate a pty\n");
  68                 return;
  69         }
  70
  71         /* Not now, but complain so we now where we failed. */
  72         err = raw(master);
  73         if (err < 0)
  74                 panic("check_sigio : __raw failed, errno = %d\n", -err);
  75
  76         err = os_sigio_async(master, slave);
  77         if(err < 0)
  78                 panic("tty_fds : sigio_async failed, err = %d\n", -err);
  79
  80         if(sigaction(SIGIO, NULL, &old) < 0)
  81                 panic("check_sigio : sigaction 1 failed, errno = %d\n", errno);
  82         new = old;
  83         new.sa_handler = handler;
  84         if(sigaction(SIGIO, &new, NULL) < 0)
  85                 panic("check_sigio : sigaction 2 failed, errno = %d\n", errno);
  86
  87         got_sigio = 0;
  88         (*proc)(master, slave);
  89
  90         os_close_file(master);
  91         os_close_file(slave);
  92
  93         if(sigaction(SIGIO, &old, NULL) < 0)
  94                 panic("check_sigio : sigaction 3 failed, errno = %d\n", errno);
  95 }
  96
  97 static void tty_output(int master, int slave)
  98 {
  99         int n;
 100         char buf[512];
 101
 102         printk("Checking that host ptys support output SIGIO...");
 103
 104         memset(buf, 0, sizeof(buf));
 105
 106         while(os_write_file(master, buf, sizeof(buf)) > 0) ;
 107         if(errno != EAGAIN)
 108                 panic("check_sigio : write failed, errno = %d\n", errno);
 109         while(((n = os_read_file(slave, buf, sizeof(buf))) > 0) && !got_sigio) ;
 110
 111         if(got_sigio){
 112                 printk("Yes\n");
 113                 pty_output_sigio = 1;
 114         }
 115         else if(n == -EAGAIN) printk("No, enabling workaround\n");
 116         else panic("check_sigio : read failed, err = %d\n", n);
 117 }
 118
 119 static void tty_close(int master, int slave)
 120 {
 121         printk("Checking that host ptys support SIGIO on close...");
 122
 123         os_close_file(slave);
 124         if(got_sigio){
 125                 printk("Yes\n");
 126                 pty_close_sigio = 1;
 127         }
 128         else printk("No, enabling workaround\n");
 129 }
 130
 131 void __init check_sigio(void)
 132 {
 133         if((os_access("/dev/ptmx", OS_ACC_R_OK) < 0) &&
 134            (os_access("/dev/ptyp0", OS_ACC_R_OK) < 0)){
 135                 printk("No pseudo-terminals available - skipping pty SIGIO "
 136                        "check\n");
 137                 return;
 138         }
 139         check_one_sigio(tty_output);
 140         check_one_sigio(tty_close);
 141 }
 142
 143 /* Protected by sigio_lock(), also used by sigio_cleanup, which is an
 144  * exitcall.
 145  */
 146 static int write_sigio_pid = -1;
 147
 148 /* These arrays are initialized before the sigio thread is started, and
 149  * the descriptors closed after it is killed.  So, it can't see them change.
 150  * On the UML side, they are changed under the sigio_lock.
 151  */
 152 static int write_sigio_fds[2] = { -1, -1 };
 153 static int sigio_private[2] = { -1, -1 };
 154
 155 struct pollfds {
 156         struct pollfd *poll;
 157         int size;
 158         int used;
 159 };
 160
 161 /* Protected by sigio_lock().  Used by the sigio thread, but the UML thread
 162  * synchronizes with it.
 163  */
 164 struct pollfds current_poll = {
 165         .poll           = NULL,
 166         .size           = 0,
 167         .used           = 0
 168 };
 169
 170 struct pollfds next_poll = {
 171         .poll           = NULL,
 172         .size           = 0,
 173         .used           = 0
 174 };
 175
 176 static int write_sigio_thread(void *unused)
 177 {
 178         struct pollfds *fds, tmp;
 179         struct pollfd *p;
 180         int i, n, respond_fd;
 181         char c;
 182
 183         fds = &current_poll;
 184         while(1){
 185                 n = poll(fds->poll, fds->used, -1);
 186                 if(n < 0){
 187                         if(errno == EINTR) continue;
 188                         printk("write_sigio_thread : poll returned %d, "
 189                                "errno = %d\n", n, errno);
 190                 }
 191                 for(i = 0; i < fds->used; i++){
 192                         p = &fds->poll[i];
 193                         if(p->revents == 0) continue;
 194                         if(p->fd == sigio_private[1]){
 195                                 n = os_read_file(sigio_private[1], &c, sizeof(c));
 196                                 if(n != sizeof(c))
 197                                         printk("write_sigio_thread : "
 198                                                "read failed, err = %d\n", -n);
 199                                 tmp = current_poll;
 200                                 current_poll = next_poll;
 201                                 next_poll = tmp;
 202                                 respond_fd = sigio_private[1];
 203                         }
 204                         else {
 205                                 respond_fd = write_sigio_fds[1];
 206                                 fds->used--;
 207                                 memmove(&fds->poll[i], &fds->poll[i + 1],
 208                                         (fds->used - i) * sizeof(*fds->poll));
 209                         }
 210
 211                         n = os_write_file(respond_fd, &c, sizeof(c));
 212                         if(n != sizeof(c))
 213                                 printk("write_sigio_thread : write failed, "
 214                                        "err = %d\n", -n);
 215                 }
 216         }
 217 }
 218
 219 static int need_poll(int n)
 220 {
 221         if(n <= next_poll.size){
 222                 next_poll.used = n;
 223                 return(0);
 224         }
 225         if(next_poll.poll != NULL) kfree(next_poll.poll);
 226         next_poll.poll = um_kmalloc_atomic(n * sizeof(struct pollfd));
 227         if(next_poll.poll == NULL){
 228                 printk("need_poll : failed to allocate new pollfds\n");
 229                 next_poll.size = 0;
 230                 next_poll.used = 0;
 231                 return(-1);
 232         }
 233         next_poll.size = n;
 234         next_poll.used = n;
 235         return(0);
 236 }
 237
 238 static void update_thread(void)
 239 {
 240         unsigned long flags;
 241         int n;
 242         char c;
 243
 244         flags = set_signals(0);
 245         n = os_write_file(sigio_private[0], &c, sizeof(c));
 246         if(n != sizeof(c)){
 247                 printk("update_thread : write failed, err = %d\n", -n);
 248                 goto fail;
 249         }
 250
 251         n = os_read_file(sigio_private[0], &c, sizeof(c));
 252         if(n != sizeof(c)){
 253                 printk("update_thread : read failed, err = %d\n", -n);
 254                 goto fail;
 255         }
 256
 257         set_signals(flags);
 258         return;
 259  fail:
 260         sigio_lock();
 261         if(write_sigio_pid != -1)
 262                 os_kill_process(write_sigio_pid, 1);
 263         write_sigio_pid = -1;
 264         os_close_file(sigio_private[0]);
 265         os_close_file(sigio_private[1]);
 266         os_close_file(write_sigio_fds[0]);
 267         os_close_file(write_sigio_fds[1]);
 268         sigio_unlock();
 269         set_signals(flags);
 270 }
 271
 272 int add_sigio_fd(int fd, int read)
 273 {
 274         int err = 0, i, n, events;
 275
 276         sigio_lock();
 277         for(i = 0; i < current_poll.used; i++){
 278                 if(current_poll.poll[i].fd == fd)
 279                         goto out;
 280         }
 281
 282         n = current_poll.used + 1;
 283         err = need_poll(n);
 284         if(err)
 285                 goto out;
 286
 287         for(i = 0; i < current_poll.used; i++)
 288                 next_poll.poll[i] = current_poll.poll[i];
 289
 290         if(read) events = POLLIN;
 291         else events = POLLOUT;
 292
 293         next_poll.poll[n - 1] = ((struct pollfd) { .fd          = fd,
 294                                                    .events      = events,
 295                                                    .revents     = 0 });
 296         update_thread();
 297  out:
 298         sigio_unlock();
 299         return(err);
 300 }
 301
 302 int ignore_sigio_fd(int fd)
 303 {
 304         struct pollfd *p;
 305         int err = 0, i, n = 0;
 306
 307         sigio_lock();
 308         for(i = 0; i < current_poll.used; i++){
 309                 if(current_poll.poll[i].fd == fd) break;
 310         }
 311         if(i == current_poll.used)
 312                 goto out;
 313
 314         err = need_poll(current_poll.used - 1);
 315         if(err)
 316                 goto out;
 317
 318         for(i = 0; i < current_poll.used; i++){
 319                 p = &current_poll.poll[i];
 320                 if(p->fd != fd) next_poll.poll[n++] = current_poll.poll[i];
 321         }
 322         if(n == i){
 323                 printk("ignore_sigio_fd : fd %d not found\n", fd);
 324                 err = -1;
 325                 goto out;
 326         }
 327
 328         update_thread();
 329  out:
 330         sigio_unlock();
 331         return(err);
 332 }
 333
 334 static int setup_initial_poll(int fd)
 335 {
 336         struct pollfd *p;
 337
 338         p = um_kmalloc(sizeof(struct pollfd));
 339         if(p == NULL){
 340                 printk("setup_initial_poll : failed to allocate poll\n");
 341                 return(-1);
 342         }
 343         *p = ((struct pollfd) { .fd     = fd,
 344                                 .events         = POLLIN,
 345                                 .revents        = 0 });
 346         current_poll = ((struct pollfds) { .poll        = p,
 347                                            .used        = 1,
 348                                            .size        = 1 });
 349         return(0);
 350 }
 351
 352 void write_sigio_workaround(void)
 353 {
 354         unsigned long stack;
 355         int err;
 356
 357         sigio_lock();
 358         if(write_sigio_pid != -1)
 359                 goto out;
 360
 361         err = os_pipe(write_sigio_fds, 1, 1);
 362         if(err < 0){
 363                 printk("write_sigio_workaround - os_pipe 1 failed, "
 364                        "err = %d\n", -err);
 365                 goto out;
 366         }
 367         err = os_pipe(sigio_private, 1, 1);
 368         if(err < 0){
 369                 printk("write_sigio_workaround - os_pipe 2 failed, "
 370                        "err = %d\n", -err);
 371                 goto out_close1;
 372         }
 373         if(setup_initial_poll(sigio_private[1]))
 374                 goto out_close2;
 375
 376         write_sigio_pid = run_helper_thread(write_sigio_thread, NULL,
 377                                             CLONE_FILES | CLONE_VM, &stack, 0);
 378
 379         if(write_sigio_pid < 0) goto out_close2;
 380
 381         if(write_sigio_irq(write_sigio_fds[0]))
 382                 goto out_kill;
 383
 384  out:
 385         sigio_unlock();
 386         return;
 387
 388  out_kill:
 389         os_kill_process(write_sigio_pid, 1);
 390         write_sigio_pid = -1;
 391  out_close2:
 392         os_close_file(sigio_private[0]);
 393         os_close_file(sigio_private[1]);
 394  out_close1:
 395         os_close_file(write_sigio_fds[0]);
 396         os_close_file(write_sigio_fds[1]);
 397         sigio_unlock();
 398 }
 399
 400 int read_sigio_fd(int fd)
 401 {
 402         int n;
 403         char c;
 404
 405         n = os_read_file(fd, &c, sizeof(c));
 406         if(n != sizeof(c)){
 407                 if(n < 0) {
 408                         printk("read_sigio_fd - read failed, err = %d\n", -n);
 409                         return(n);
 410                 }
 411                 else {
 412                         printk("read_sigio_fd - short read, bytes = %d\n", n);
 413                         return(-EIO);
 414                 }
 415         }
 416         return(n);
 417 }
 418
 419 static void sigio_cleanup(void)
 420 {
 421         if(write_sigio_pid != -1)
 422                 os_kill_process(write_sigio_pid, 1);
 423 }
 424
 425 __uml_exitcall(sigio_cleanup);
 426
 427 /*
 428  * Overrides for Emacs so that we follow Linus's tabbing style.
 429  * Emacs will notice this stuff at the end of the file and automatically
 430  * adjust the settings for this buffer only.  This must remain at the end
 431  * of the file.
 432  * ---------------------------------------------------------------------------
 433  * Local variables:
 434  * c-file-style: "linux"
 435  * End:
 436  */