| 1 | /* |
| 2 | * Copyright (c) 1982, 1986, 1989, 1991, 1993 |
| 3 | * The Regents of the University of California. All rights reserved. |
| 4 | * (c) UNIX System Laboratories, Inc. |
| 5 | * All or some portions of this file are derived from material licensed |
| 6 | * to the University of California by American Telephone and Telegraph |
| 7 | * Co. or Unix System Laboratories, Inc. and are reproduced herein with |
| 8 | * the permission of UNIX System Laboratories, Inc. |
| 9 | * |
| 10 | * Redistribution and use in source and binary forms, with or without |
| 11 | * modification, are permitted provided that the following conditions |
| 12 | * are met: |
| 13 | * 1. Redistributions of source code must retain the above copyright |
| 14 | * notice, this list of conditions and the following disclaimer. |
| 15 | * 2. Redistributions in binary form must reproduce the above copyright |
| 16 | * notice, this list of conditions and the following disclaimer in the |
| 17 | * documentation and/or other materials provided with the distribution. |
| 18 | * 3. All advertising materials mentioning features or use of this software |
| 19 | * must display the following acknowledgement: |
| 20 | * This product includes software developed by the University of |
| 21 | * California, Berkeley and its contributors. |
| 22 | * 4. Neither the name of the University nor the names of its contributors |
| 23 | * may be used to endorse or promote products derived from this software |
| 24 | * without specific prior written permission. |
| 25 | * |
| 26 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
| 27 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 28 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| 29 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
| 30 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| 31 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| 32 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| 33 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| 34 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| 35 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| 36 | * SUCH DAMAGE. |
| 37 | * |
| 38 | * @(#)kern_fork.c 8.6 (Berkeley) 4/8/94 |
| 39 | * $FreeBSD: src/sys/kern/kern_fork.c,v 1.72.2.14 2003/06/26 04:15:10 silby Exp $ |
| 40 | * $DragonFly: src/sys/kern/kern_fork.c,v 1.29 2004/09/17 01:29:45 joerg Exp $ |
| 41 | */ |
| 42 | |
| 43 | #include "opt_ktrace.h" |
| 44 | |
| 45 | #include <sys/param.h> |
| 46 | #include <sys/systm.h> |
| 47 | #include <sys/sysproto.h> |
| 48 | #include <sys/filedesc.h> |
| 49 | #include <sys/kernel.h> |
| 50 | #include <sys/sysctl.h> |
| 51 | #include <sys/malloc.h> |
| 52 | #include <sys/proc.h> |
| 53 | #include <sys/resourcevar.h> |
| 54 | #include <sys/vnode.h> |
| 55 | #include <sys/acct.h> |
| 56 | #include <sys/ktrace.h> |
| 57 | #include <sys/unistd.h> |
| 58 | #include <sys/jail.h> |
| 59 | #include <sys/caps.h> |
| 60 | |
| 61 | #include <vm/vm.h> |
| 62 | #include <sys/lock.h> |
| 63 | #include <vm/pmap.h> |
| 64 | #include <vm/vm_map.h> |
| 65 | #include <vm/vm_extern.h> |
| 66 | #include <vm/vm_zone.h> |
| 67 | |
| 68 | #include <sys/vmmeter.h> |
| 69 | #include <sys/user.h> |
| 70 | |
| 71 | static MALLOC_DEFINE(M_ATFORK, "atfork", "atfork callback"); |
| 72 | |
| 73 | /* |
| 74 | * These are the stuctures used to create a callout list for things to do |
| 75 | * when forking a process |
| 76 | */ |
| 77 | struct forklist { |
| 78 | forklist_fn function; |
| 79 | TAILQ_ENTRY(forklist) next; |
| 80 | }; |
| 81 | |
| 82 | TAILQ_HEAD(forklist_head, forklist); |
| 83 | static struct forklist_head fork_list = TAILQ_HEAD_INITIALIZER(fork_list); |
| 84 | |
| 85 | int forksleep; /* Place for fork1() to sleep on. */ |
| 86 | |
| 87 | /* ARGSUSED */ |
| 88 | int |
| 89 | fork(struct fork_args *uap) |
| 90 | { |
| 91 | struct proc *p = curproc; |
| 92 | struct proc *p2; |
| 93 | int error; |
| 94 | |
| 95 | error = fork1(p, RFFDG | RFPROC, &p2); |
| 96 | if (error == 0) { |
| 97 | start_forked_proc(p, p2); |
| 98 | uap->sysmsg_fds[0] = p2->p_pid; |
| 99 | uap->sysmsg_fds[1] = 0; |
| 100 | } |
| 101 | return error; |
| 102 | } |
| 103 | |
| 104 | /* ARGSUSED */ |
| 105 | int |
| 106 | vfork(struct vfork_args *uap) |
| 107 | { |
| 108 | struct proc *p = curproc; |
| 109 | struct proc *p2; |
| 110 | int error; |
| 111 | |
| 112 | error = fork1(p, RFFDG | RFPROC | RFPPWAIT | RFMEM, &p2); |
| 113 | if (error == 0) { |
| 114 | start_forked_proc(p, p2); |
| 115 | uap->sysmsg_fds[0] = p2->p_pid; |
| 116 | uap->sysmsg_fds[1] = 0; |
| 117 | } |
| 118 | return error; |
| 119 | } |
| 120 | |
| 121 | /* |
| 122 | * Handle rforks. An rfork may (1) operate on the current process without |
| 123 | * creating a new, (2) create a new process that shared the current process's |
| 124 | * vmspace, signals, and/or descriptors, or (3) create a new process that does |
| 125 | * not share these things (normal fork). |
| 126 | * |
| 127 | * Note that we only call start_forked_proc() if a new process is actually |
| 128 | * created. |
| 129 | * |
| 130 | * rfork { int flags } |
| 131 | */ |
| 132 | int |
| 133 | rfork(struct rfork_args *uap) |
| 134 | { |
| 135 | struct proc *p = curproc; |
| 136 | struct proc *p2; |
| 137 | int error; |
| 138 | |
| 139 | if ((uap->flags & RFKERNELONLY) != 0) |
| 140 | return (EINVAL); |
| 141 | |
| 142 | error = fork1(p, uap->flags, &p2); |
| 143 | if (error == 0) { |
| 144 | if (p2) |
| 145 | start_forked_proc(p, p2); |
| 146 | uap->sysmsg_fds[0] = p2 ? p2->p_pid : 0; |
| 147 | uap->sysmsg_fds[1] = 0; |
| 148 | } |
| 149 | return error; |
| 150 | } |
| 151 | |
| 152 | |
| 153 | int nprocs = 1; /* process 0 */ |
| 154 | static int nextpid = 0; |
| 155 | |
| 156 | /* |
| 157 | * Random component to nextpid generation. We mix in a random factor to make |
| 158 | * it a little harder to predict. We sanity check the modulus value to avoid |
| 159 | * doing it in critical paths. Don't let it be too small or we pointlessly |
| 160 | * waste randomness entropy, and don't let it be impossibly large. Using a |
| 161 | * modulus that is too big causes a LOT more process table scans and slows |
| 162 | * down fork processing as the pidchecked caching is defeated. |
| 163 | */ |
| 164 | static int randompid = 0; |
| 165 | |
| 166 | static int |
| 167 | sysctl_kern_randompid(SYSCTL_HANDLER_ARGS) |
| 168 | { |
| 169 | int error, pid; |
| 170 | |
| 171 | pid = randompid; |
| 172 | error = sysctl_handle_int(oidp, &pid, 0, req); |
| 173 | if (error || !req->newptr) |
| 174 | return (error); |
| 175 | if (pid < 0 || pid > PID_MAX - 100) /* out of range */ |
| 176 | pid = PID_MAX - 100; |
| 177 | else if (pid < 2) /* NOP */ |
| 178 | pid = 0; |
| 179 | else if (pid < 100) /* Make it reasonable */ |
| 180 | pid = 100; |
| 181 | randompid = pid; |
| 182 | return (error); |
| 183 | } |
| 184 | |
| 185 | SYSCTL_PROC(_kern, OID_AUTO, randompid, CTLTYPE_INT|CTLFLAG_RW, |
| 186 | 0, 0, sysctl_kern_randompid, "I", "Random PID modulus"); |
| 187 | |
| 188 | int |
| 189 | fork1(struct proc *p1, int flags, struct proc **procp) |
| 190 | { |
| 191 | struct proc *p2, *pptr; |
| 192 | uid_t uid; |
| 193 | struct proc *newproc; |
| 194 | int ok; |
| 195 | static int curfail = 0, pidchecked = 0; |
| 196 | static struct timeval lastfail; |
| 197 | struct forklist *ep; |
| 198 | struct filedesc_to_leader *fdtol; |
| 199 | |
| 200 | if ((flags & (RFFDG|RFCFDG)) == (RFFDG|RFCFDG)) |
| 201 | return (EINVAL); |
| 202 | |
| 203 | /* |
| 204 | * Here we don't create a new process, but we divorce |
| 205 | * certain parts of a process from itself. |
| 206 | */ |
| 207 | if ((flags & RFPROC) == 0) { |
| 208 | |
| 209 | vm_fork(p1, 0, flags); |
| 210 | |
| 211 | /* |
| 212 | * Close all file descriptors. |
| 213 | */ |
| 214 | if (flags & RFCFDG) { |
| 215 | struct filedesc *fdtmp; |
| 216 | fdtmp = fdinit(p1); |
| 217 | fdfree(p1); |
| 218 | p1->p_fd = fdtmp; |
| 219 | } |
| 220 | |
| 221 | /* |
| 222 | * Unshare file descriptors (from parent.) |
| 223 | */ |
| 224 | if (flags & RFFDG) { |
| 225 | if (p1->p_fd->fd_refcnt > 1) { |
| 226 | struct filedesc *newfd; |
| 227 | newfd = fdcopy(p1); |
| 228 | fdfree(p1); |
| 229 | p1->p_fd = newfd; |
| 230 | } |
| 231 | } |
| 232 | *procp = NULL; |
| 233 | return (0); |
| 234 | } |
| 235 | |
| 236 | /* |
| 237 | * Although process entries are dynamically created, we still keep |
| 238 | * a global limit on the maximum number we will create. Don't allow |
| 239 | * a nonprivileged user to use the last ten processes; don't let root |
| 240 | * exceed the limit. The variable nprocs is the current number of |
| 241 | * processes, maxproc is the limit. |
| 242 | */ |
| 243 | uid = p1->p_ucred->cr_ruid; |
| 244 | if ((nprocs >= maxproc - 10 && uid != 0) || nprocs >= maxproc) { |
| 245 | if (ppsratecheck(&lastfail, &curfail, 1)) |
| 246 | printf("maxproc limit exceeded by uid %d, please " |
| 247 | "see tuning(7) and login.conf(5).\n", uid); |
| 248 | tsleep(&forksleep, 0, "fork", hz / 2); |
| 249 | return (EAGAIN); |
| 250 | } |
| 251 | /* |
| 252 | * Increment the nprocs resource before blocking can occur. There |
| 253 | * are hard-limits as to the number of processes that can run. |
| 254 | */ |
| 255 | nprocs++; |
| 256 | |
| 257 | /* |
| 258 | * Increment the count of procs running with this uid. Don't allow |
| 259 | * a nonprivileged user to exceed their current limit. |
| 260 | */ |
| 261 | ok = chgproccnt(p1->p_ucred->cr_ruidinfo, 1, |
| 262 | (uid != 0) ? p1->p_rlimit[RLIMIT_NPROC].rlim_cur : 0); |
| 263 | if (!ok) { |
| 264 | /* |
| 265 | * Back out the process count |
| 266 | */ |
| 267 | nprocs--; |
| 268 | if (ppsratecheck(&lastfail, &curfail, 1)) |
| 269 | printf("maxproc limit exceeded by uid %d, please " |
| 270 | "see tuning(7) and login.conf(5).\n", uid); |
| 271 | tsleep(&forksleep, 0, "fork", hz / 2); |
| 272 | return (EAGAIN); |
| 273 | } |
| 274 | |
| 275 | /* Allocate new proc. */ |
| 276 | newproc = zalloc(proc_zone); |
| 277 | |
| 278 | /* |
| 279 | * Setup linkage for kernel based threading |
| 280 | */ |
| 281 | if ((flags & RFTHREAD) != 0) { |
| 282 | newproc->p_peers = p1->p_peers; |
| 283 | p1->p_peers = newproc; |
| 284 | newproc->p_leader = p1->p_leader; |
| 285 | } else { |
| 286 | newproc->p_peers = 0; |
| 287 | newproc->p_leader = newproc; |
| 288 | } |
| 289 | |
| 290 | newproc->p_wakeup = 0; |
| 291 | newproc->p_vmspace = NULL; |
| 292 | TAILQ_INIT(&newproc->p_sysmsgq); |
| 293 | |
| 294 | /* |
| 295 | * Find an unused process ID. We remember a range of unused IDs |
| 296 | * ready to use (from nextpid+1 through pidchecked-1). |
| 297 | */ |
| 298 | nextpid++; |
| 299 | if (randompid) |
| 300 | nextpid += arc4random() % randompid; |
| 301 | retry: |
| 302 | /* |
| 303 | * If the process ID prototype has wrapped around, |
| 304 | * restart somewhat above 0, as the low-numbered procs |
| 305 | * tend to include daemons that don't exit. |
| 306 | */ |
| 307 | if (nextpid >= PID_MAX) { |
| 308 | nextpid = nextpid % PID_MAX; |
| 309 | if (nextpid < 100) |
| 310 | nextpid += 100; |
| 311 | pidchecked = 0; |
| 312 | } |
| 313 | if (nextpid >= pidchecked) { |
| 314 | int doingzomb = 0; |
| 315 | |
| 316 | pidchecked = PID_MAX; |
| 317 | /* |
| 318 | * Scan the active and zombie procs to check whether this pid |
| 319 | * is in use. Remember the lowest pid that's greater |
| 320 | * than nextpid, so we can avoid checking for a while. |
| 321 | */ |
| 322 | p2 = LIST_FIRST(&allproc); |
| 323 | again: |
| 324 | for (; p2 != 0; p2 = LIST_NEXT(p2, p_list)) { |
| 325 | while (p2->p_pid == nextpid || |
| 326 | p2->p_pgrp->pg_id == nextpid || |
| 327 | p2->p_session->s_sid == nextpid) { |
| 328 | nextpid++; |
| 329 | if (nextpid >= pidchecked) |
| 330 | goto retry; |
| 331 | } |
| 332 | if (p2->p_pid > nextpid && pidchecked > p2->p_pid) |
| 333 | pidchecked = p2->p_pid; |
| 334 | if (p2->p_pgrp->pg_id > nextpid && |
| 335 | pidchecked > p2->p_pgrp->pg_id) |
| 336 | pidchecked = p2->p_pgrp->pg_id; |
| 337 | if (p2->p_session->s_sid > nextpid && |
| 338 | pidchecked > p2->p_session->s_sid) |
| 339 | pidchecked = p2->p_session->s_sid; |
| 340 | } |
| 341 | if (!doingzomb) { |
| 342 | doingzomb = 1; |
| 343 | p2 = LIST_FIRST(&zombproc); |
| 344 | goto again; |
| 345 | } |
| 346 | } |
| 347 | |
| 348 | p2 = newproc; |
| 349 | p2->p_stat = SIDL; /* protect against others */ |
| 350 | p2->p_pid = nextpid; |
| 351 | LIST_INSERT_HEAD(&allproc, p2, p_list); |
| 352 | LIST_INSERT_HEAD(PIDHASH(p2->p_pid), p2, p_hash); |
| 353 | |
| 354 | /* |
| 355 | * Make a proc table entry for the new process. |
| 356 | * Start by zeroing the section of proc that is zero-initialized, |
| 357 | * then copy the section that is copied directly from the parent. |
| 358 | */ |
| 359 | bzero(&p2->p_startzero, |
| 360 | (unsigned) ((caddr_t)&p2->p_endzero - (caddr_t)&p2->p_startzero)); |
| 361 | bcopy(&p1->p_startcopy, &p2->p_startcopy, |
| 362 | (unsigned) ((caddr_t)&p2->p_endcopy - (caddr_t)&p2->p_startcopy)); |
| 363 | |
| 364 | p2->p_aioinfo = NULL; |
| 365 | |
| 366 | /* |
| 367 | * Duplicate sub-structures as needed. |
| 368 | * Increase reference counts on shared objects. |
| 369 | * The p_stats and p_sigacts substructs are set in vm_fork. |
| 370 | */ |
| 371 | p2->p_flag = P_INMEM; |
| 372 | if (p1->p_flag & P_PROFIL) |
| 373 | startprofclock(p2); |
| 374 | p2->p_ucred = crhold(p1->p_ucred); |
| 375 | |
| 376 | if (p2->p_ucred->cr_prison) { |
| 377 | p2->p_ucred->cr_prison->pr_ref++; |
| 378 | p2->p_flag |= P_JAILED; |
| 379 | } |
| 380 | |
| 381 | if (p2->p_args) |
| 382 | p2->p_args->ar_ref++; |
| 383 | |
| 384 | if (flags & RFSIGSHARE) { |
| 385 | p2->p_procsig = p1->p_procsig; |
| 386 | p2->p_procsig->ps_refcnt++; |
| 387 | if (p1->p_sigacts == &p1->p_addr->u_sigacts) { |
| 388 | struct sigacts *newsigacts; |
| 389 | int s; |
| 390 | |
| 391 | /* Create the shared sigacts structure */ |
| 392 | MALLOC(newsigacts, struct sigacts *, |
| 393 | sizeof(struct sigacts), M_SUBPROC, M_WAITOK); |
| 394 | s = splhigh(); |
| 395 | /* |
| 396 | * Set p_sigacts to the new shared structure. |
| 397 | * Note that this is updating p1->p_sigacts at the |
| 398 | * same time, since p_sigacts is just a pointer to |
| 399 | * the shared p_procsig->ps_sigacts. |
| 400 | */ |
| 401 | p2->p_sigacts = newsigacts; |
| 402 | bcopy(&p1->p_addr->u_sigacts, p2->p_sigacts, |
| 403 | sizeof(*p2->p_sigacts)); |
| 404 | *p2->p_sigacts = p1->p_addr->u_sigacts; |
| 405 | splx(s); |
| 406 | } |
| 407 | } else { |
| 408 | MALLOC(p2->p_procsig, struct procsig *, sizeof(struct procsig), |
| 409 | M_SUBPROC, M_WAITOK); |
| 410 | bcopy(p1->p_procsig, p2->p_procsig, sizeof(*p2->p_procsig)); |
| 411 | p2->p_procsig->ps_refcnt = 1; |
| 412 | p2->p_sigacts = NULL; /* finished in vm_fork() */ |
| 413 | } |
| 414 | if (flags & RFLINUXTHPN) |
| 415 | p2->p_sigparent = SIGUSR1; |
| 416 | else |
| 417 | p2->p_sigparent = SIGCHLD; |
| 418 | |
| 419 | /* bump references to the text vnode (for procfs) */ |
| 420 | p2->p_textvp = p1->p_textvp; |
| 421 | if (p2->p_textvp) |
| 422 | vref(p2->p_textvp); |
| 423 | |
| 424 | if (flags & RFCFDG) { |
| 425 | p2->p_fd = fdinit(p1); |
| 426 | fdtol = NULL; |
| 427 | } else if (flags & RFFDG) { |
| 428 | p2->p_fd = fdcopy(p1); |
| 429 | fdtol = NULL; |
| 430 | } else { |
| 431 | p2->p_fd = fdshare(p1); |
| 432 | if (p1->p_fdtol == NULL) |
| 433 | p1->p_fdtol = |
| 434 | filedesc_to_leader_alloc(NULL, |
| 435 | p1->p_leader); |
| 436 | if ((flags & RFTHREAD) != 0) { |
| 437 | /* |
| 438 | * Shared file descriptor table and |
| 439 | * shared process leaders. |
| 440 | */ |
| 441 | fdtol = p1->p_fdtol; |
| 442 | fdtol->fdl_refcount++; |
| 443 | } else { |
| 444 | /* |
| 445 | * Shared file descriptor table, and |
| 446 | * different process leaders |
| 447 | */ |
| 448 | fdtol = filedesc_to_leader_alloc(p1->p_fdtol, p2); |
| 449 | } |
| 450 | } |
| 451 | p2->p_fdtol = fdtol; |
| 452 | |
| 453 | /* |
| 454 | * If p_limit is still copy-on-write, bump refcnt, |
| 455 | * otherwise get a copy that won't be modified. |
| 456 | * (If PL_SHAREMOD is clear, the structure is shared |
| 457 | * copy-on-write.) |
| 458 | */ |
| 459 | if (p1->p_limit->p_lflags & PL_SHAREMOD) { |
| 460 | p2->p_limit = limcopy(p1->p_limit); |
| 461 | } else { |
| 462 | p2->p_limit = p1->p_limit; |
| 463 | p2->p_limit->p_refcnt++; |
| 464 | } |
| 465 | |
| 466 | /* |
| 467 | * Preserve some more flags in subprocess. P_PROFIL has already |
| 468 | * been preserved. |
| 469 | */ |
| 470 | p2->p_flag |= p1->p_flag & (P_SUGID | P_ALTSTACK); |
| 471 | if (p1->p_session->s_ttyvp != NULL && p1->p_flag & P_CONTROLT) |
| 472 | p2->p_flag |= P_CONTROLT; |
| 473 | if (flags & RFPPWAIT) |
| 474 | p2->p_flag |= P_PPWAIT; |
| 475 | |
| 476 | LIST_INSERT_AFTER(p1, p2, p_pglist); |
| 477 | |
| 478 | /* |
| 479 | * Attach the new process to its parent. |
| 480 | * |
| 481 | * If RFNOWAIT is set, the newly created process becomes a child |
| 482 | * of init. This effectively disassociates the child from the |
| 483 | * parent. |
| 484 | */ |
| 485 | if (flags & RFNOWAIT) |
| 486 | pptr = initproc; |
| 487 | else |
| 488 | pptr = p1; |
| 489 | p2->p_pptr = pptr; |
| 490 | LIST_INSERT_HEAD(&pptr->p_children, p2, p_sibling); |
| 491 | LIST_INIT(&p2->p_children); |
| 492 | varsymset_init(&p2->p_varsymset, &p1->p_varsymset); |
| 493 | callout_init(&p2->p_ithandle); |
| 494 | |
| 495 | #ifdef KTRACE |
| 496 | /* |
| 497 | * Copy traceflag and tracefile if enabled. If not inherited, |
| 498 | * these were zeroed above but we still could have a trace race |
| 499 | * so make sure p2's p_tracep is NULL. |
| 500 | */ |
| 501 | if ((p1->p_traceflag & KTRFAC_INHERIT) && p2->p_tracep == NULL) { |
| 502 | p2->p_traceflag = p1->p_traceflag; |
| 503 | if ((p2->p_tracep = p1->p_tracep) != NULL) |
| 504 | vref(p2->p_tracep); |
| 505 | } |
| 506 | #endif |
| 507 | |
| 508 | /* |
| 509 | * Give the child process an estcpu skewed towards the batch side |
| 510 | * of the parent. This prevents batch programs from glitching |
| 511 | * interactive programs when they are first started. If the child |
| 512 | * is not a batch program it's priority will be corrected by the |
| 513 | * scheduler. |
| 514 | * |
| 515 | * The interactivity model always starts at 0 (par value). |
| 516 | */ |
| 517 | p2->p_estcpu_fork = p2->p_estcpu = |
| 518 | ESTCPULIM(p1->p_estcpu + ESTCPURAMP); |
| 519 | p2->p_interactive = 0; |
| 520 | |
| 521 | /* |
| 522 | * This begins the section where we must prevent the parent |
| 523 | * from being swapped. |
| 524 | */ |
| 525 | PHOLD(p1); |
| 526 | |
| 527 | /* |
| 528 | * Finish creating the child process. It will return via a different |
| 529 | * execution path later. (ie: directly into user mode) |
| 530 | */ |
| 531 | vm_fork(p1, p2, flags); |
| 532 | caps_fork(p1, p2, flags); |
| 533 | |
| 534 | if (flags == (RFFDG | RFPROC)) { |
| 535 | mycpu->gd_cnt.v_forks++; |
| 536 | mycpu->gd_cnt.v_forkpages += p2->p_vmspace->vm_dsize + p2->p_vmspace->vm_ssize; |
| 537 | } else if (flags == (RFFDG | RFPROC | RFPPWAIT | RFMEM)) { |
| 538 | mycpu->gd_cnt.v_vforks++; |
| 539 | mycpu->gd_cnt.v_vforkpages += p2->p_vmspace->vm_dsize + p2->p_vmspace->vm_ssize; |
| 540 | } else if (p1 == &proc0) { |
| 541 | mycpu->gd_cnt.v_kthreads++; |
| 542 | mycpu->gd_cnt.v_kthreadpages += p2->p_vmspace->vm_dsize + p2->p_vmspace->vm_ssize; |
| 543 | } else { |
| 544 | mycpu->gd_cnt.v_rforks++; |
| 545 | mycpu->gd_cnt.v_rforkpages += p2->p_vmspace->vm_dsize + p2->p_vmspace->vm_ssize; |
| 546 | } |
| 547 | |
| 548 | /* |
| 549 | * Both processes are set up, now check if any loadable modules want |
| 550 | * to adjust anything. |
| 551 | * What if they have an error? XXX |
| 552 | */ |
| 553 | TAILQ_FOREACH(ep, &fork_list, next) { |
| 554 | (*ep->function)(p1, p2, flags); |
| 555 | } |
| 556 | |
| 557 | /* |
| 558 | * Make child runnable and add to run queue. |
| 559 | */ |
| 560 | microtime(&p2->p_thread->td_start); |
| 561 | p2->p_acflag = AFORK; |
| 562 | |
| 563 | /* |
| 564 | * tell any interested parties about the new process |
| 565 | */ |
| 566 | KNOTE(&p1->p_klist, NOTE_FORK | p2->p_pid); |
| 567 | |
| 568 | /* |
| 569 | * Return child proc pointer to parent. |
| 570 | */ |
| 571 | *procp = p2; |
| 572 | return (0); |
| 573 | } |
| 574 | |
| 575 | /* |
| 576 | * The next two functionms are general routines to handle adding/deleting |
| 577 | * items on the fork callout list. |
| 578 | * |
| 579 | * at_fork(): |
| 580 | * Take the arguments given and put them onto the fork callout list, |
| 581 | * However first make sure that it's not already there. |
| 582 | * Returns 0 on success or a standard error number. |
| 583 | */ |
| 584 | int |
| 585 | at_fork(forklist_fn function) |
| 586 | { |
| 587 | struct forklist *ep; |
| 588 | |
| 589 | #ifdef INVARIANTS |
| 590 | /* let the programmer know if he's been stupid */ |
| 591 | if (rm_at_fork(function)) { |
| 592 | printf("WARNING: fork callout entry (%p) already present\n", |
| 593 | function); |
| 594 | } |
| 595 | #endif |
| 596 | ep = malloc(sizeof(*ep), M_ATFORK, M_WAITOK|M_ZERO); |
| 597 | ep->function = function; |
| 598 | TAILQ_INSERT_TAIL(&fork_list, ep, next); |
| 599 | return (0); |
| 600 | } |
| 601 | |
| 602 | /* |
| 603 | * Scan the exit callout list for the given item and remove it.. |
| 604 | * Returns the number of items removed (0 or 1) |
| 605 | */ |
| 606 | int |
| 607 | rm_at_fork(forklist_fn function) |
| 608 | { |
| 609 | struct forklist *ep; |
| 610 | |
| 611 | TAILQ_FOREACH(ep, &fork_list, next) { |
| 612 | if (ep->function == function) { |
| 613 | TAILQ_REMOVE(&fork_list, ep, next); |
| 614 | free(ep, M_ATFORK); |
| 615 | return(1); |
| 616 | } |
| 617 | } |
| 618 | return (0); |
| 619 | } |
| 620 | |
| 621 | /* |
| 622 | * Add a forked process to the run queue after any remaining setup, such |
| 623 | * as setting the fork handler, has been completed. |
| 624 | */ |
| 625 | void |
| 626 | start_forked_proc(struct proc *p1, struct proc *p2) |
| 627 | { |
| 628 | /* |
| 629 | * Move from SIDL to RUN queue, and activate the process's thread. |
| 630 | * Activation of the thread effectively makes the process "a" |
| 631 | * current process, so we do not setrunqueue(). |
| 632 | * |
| 633 | * YYY setrunqueue works here but we should clean up the trampoline |
| 634 | * code so we just schedule the LWKT thread and let the trampoline |
| 635 | * deal with the userland scheduler on return to userland. |
| 636 | */ |
| 637 | KASSERT(p2 && p2->p_stat == SIDL, |
| 638 | ("cannot start forked process, bad status: %p", p2)); |
| 639 | resetpriority(p2); |
| 640 | (void) splhigh(); |
| 641 | p2->p_stat = SRUN; |
| 642 | setrunqueue(p2); |
| 643 | (void) spl0(); |
| 644 | |
| 645 | /* |
| 646 | * Now can be swapped. |
| 647 | */ |
| 648 | PRELE(p1); |
| 649 | |
| 650 | /* |
| 651 | * Preserve synchronization semantics of vfork. If waiting for |
| 652 | * child to exec or exit, set P_PPWAIT on child, and sleep on our |
| 653 | * proc (in case of exit). |
| 654 | */ |
| 655 | while (p2->p_flag & P_PPWAIT) |
| 656 | tsleep(p1, 0, "ppwait", 0); |
| 657 | } |
| 658 | |