sys/kern/sysv_sem.c

   1 /* $FreeBSD: src/sys/kern/sysv_sem.c,v 1.69 2004/03/17 09:37:13 cperciva Exp $ */
   2 /* $DragonFly: src/sys/kern/sysv_sem.c,v 1.18 2006/12/23 23:47:54 swildner Exp $ */
   3
   4 /*
   5  * Implementation of SVID semaphores
   6  *
   7  * Author:  Daniel Boulet
   8  *
   9  * This software is provided ``AS IS'' without any warranties of any kind.
  10  */
  11
  12 #include "opt_sysvipc.h"
  13
  14 #include <sys/param.h>
  15 #include <sys/systm.h>
  16 #include <sys/sysproto.h>
  17 #include <sys/kernel.h>
  18 #include <sys/proc.h>
  19 #include <sys/sem.h>
  20 #include <sys/sysent.h>
  21 #include <sys/sysctl.h>
  22 #include <sys/malloc.h>
  23 #include <sys/jail.h>
  24
  25 static MALLOC_DEFINE(M_SEM, "sem", "SVID compatible semaphores");
  26
  27 static void seminit (void *);
  28
  29 static struct sem_undo *semu_alloc (struct proc *p);
  30 static int semundo_adjust (struct proc *p, struct sem_undo **supptr,
  31                 int semid, int semnum, int adjval);
  32 static void semundo_clear (int semid, int semnum);
  33
  34 /* XXX casting to (sy_call_t *) is bogus, as usual. */
  35 static sy_call_t *semcalls[] = {
  36         (sy_call_t *)sys___semctl, (sy_call_t *)sys_semget,
  37         (sy_call_t *)sys_semop
  38 };
  39
  40 static int      semtot = 0;
  41 static struct semid_ds *sema;   /* semaphore id pool */
  42 static struct sem *sem;         /* semaphore pool */
  43 static struct sem_undo *semu_list; /* list of active undo structures */
  44 static int      *semu;          /* undo structure pool */
  45
  46 struct sem {
  47         u_short semval;         /* semaphore value */
  48         pid_t   sempid;         /* pid of last operation */
  49         u_short semncnt;        /* # awaiting semval > cval */
  50         u_short semzcnt;        /* # awaiting semval = 0 */
  51 };
  52
  53 /*
  54  * Undo structure (one per process)
  55  */
  56 struct sem_undo {
  57         struct  sem_undo *un_next;      /* ptr to next active undo structure */
  58         struct  proc *un_proc;          /* owner of this structure */
  59         short   un_cnt;                 /* # of active entries */
  60         struct undo {
  61                 short   un_adjval;      /* adjust on exit values */
  62                 short   un_num;         /* semaphore # */
  63                 int     un_id;          /* semid */
  64         } un_ent[1];                    /* undo entries */
  65 };
  66
  67 /*
  68  * Configuration parameters
  69  */
  70 #ifndef SEMMNI
  71 #define SEMMNI  10              /* # of semaphore identifiers */
  72 #endif
  73 #ifndef SEMMNS
  74 #define SEMMNS  60              /* # of semaphores in system */
  75 #endif
  76 #ifndef SEMUME
  77 #define SEMUME  10              /* max # of undo entries per process */
  78 #endif
  79 #ifndef SEMMNU
  80 #define SEMMNU  30              /* # of undo structures in system */
  81 #endif
  82
  83 /* shouldn't need tuning */
  84 #ifndef SEMMAP
  85 #define SEMMAP  30              /* # of entries in semaphore map */
  86 #endif
  87 #ifndef SEMMSL
  88 #define SEMMSL  SEMMNS          /* max # of semaphores per id */
  89 #endif
  90 #ifndef SEMOPM
  91 #define SEMOPM  100             /* max # of operations per semop call */
  92 #endif
  93
  94 #define SEMVMX  32767           /* semaphore maximum value */
  95 #define SEMAEM  16384           /* adjust on exit max value */
  96
  97 /*
  98  * Due to the way semaphore memory is allocated, we have to ensure that
  99  * SEMUSZ is properly aligned.
 100  */
 101
 102 #define SEM_ALIGN(bytes) (((bytes) + (sizeof(long) - 1)) & ~(sizeof(long) - 1))
 103
 104 /* actual size of an undo structure */
 105 #define SEMUSZ  SEM_ALIGN(offsetof(struct sem_undo, un_ent[SEMUME]))
 106
 107 /*
 108  * Macro to find a particular sem_undo vector
 109  */
 110 #define SEMU(ix)        ((struct sem_undo *)(((intptr_t)semu)+ix * seminfo.semusz))
 111
 112 /*
 113  * semaphore info struct
 114  */
 115 struct seminfo seminfo = {
 116                 SEMMAP,         /* # of entries in semaphore map */
 117                 SEMMNI,         /* # of semaphore identifiers */
 118                 SEMMNS,         /* # of semaphores in system */
 119                 SEMMNU,         /* # of undo structures in system */
 120                 SEMMSL,         /* max # of semaphores per id */
 121                 SEMOPM,         /* max # of operations per semop call */
 122                 SEMUME,         /* max # of undo entries per process */
 123                 SEMUSZ,         /* size in bytes of undo structure */
 124                 SEMVMX,         /* semaphore maximum value */
 125                 SEMAEM          /* adjust on exit max value */
 126 };
 127
 128 TUNABLE_INT("kern.ipc.semmap", &seminfo.semmap);
 129 TUNABLE_INT("kern.ipc.semmni", &seminfo.semmni);
 130 TUNABLE_INT("kern.ipc.semmns", &seminfo.semmns);
 131 TUNABLE_INT("kern.ipc.semmnu", &seminfo.semmnu);
 132 TUNABLE_INT("kern.ipc.semmsl", &seminfo.semmsl);
 133 TUNABLE_INT("kern.ipc.semopm", &seminfo.semopm);
 134 TUNABLE_INT("kern.ipc.semume", &seminfo.semume);
 135 TUNABLE_INT("kern.ipc.semusz", &seminfo.semusz);
 136 TUNABLE_INT("kern.ipc.semvmx", &seminfo.semvmx);
 137 TUNABLE_INT("kern.ipc.semaem", &seminfo.semaem);
 138
 139 SYSCTL_INT(_kern_ipc, OID_AUTO, semmap, CTLFLAG_RW, &seminfo.semmap, 0, "");
 140 SYSCTL_INT(_kern_ipc, OID_AUTO, semmni, CTLFLAG_RD, &seminfo.semmni, 0, "");
 141 SYSCTL_INT(_kern_ipc, OID_AUTO, semmns, CTLFLAG_RD, &seminfo.semmns, 0, "");
 142 SYSCTL_INT(_kern_ipc, OID_AUTO, semmnu, CTLFLAG_RD, &seminfo.semmnu, 0, "");
 143 SYSCTL_INT(_kern_ipc, OID_AUTO, semmsl, CTLFLAG_RW, &seminfo.semmsl, 0, "");
 144 SYSCTL_INT(_kern_ipc, OID_AUTO, semopm, CTLFLAG_RD, &seminfo.semopm, 0, "");
 145 SYSCTL_INT(_kern_ipc, OID_AUTO, semume, CTLFLAG_RD, &seminfo.semume, 0, "");
 146 SYSCTL_INT(_kern_ipc, OID_AUTO, semusz, CTLFLAG_RD, &seminfo.semusz, 0, "");
 147 SYSCTL_INT(_kern_ipc, OID_AUTO, semvmx, CTLFLAG_RW, &seminfo.semvmx, 0, "");
 148 SYSCTL_INT(_kern_ipc, OID_AUTO, semaem, CTLFLAG_RW, &seminfo.semaem, 0, "");
 149
 150 #if 0
 151 RO seminfo.semmap       /* SEMMAP unused */
 152 RO seminfo.semmni
 153 RO seminfo.semmns
 154 RO seminfo.semmnu       /* undo entries per system */
 155 RW seminfo.semmsl
 156 RO seminfo.semopm       /* SEMOPM unused */
 157 RO seminfo.semume
 158 RO seminfo.semusz       /* param - derived from SEMUME for per-proc sizeof */
 159 RO seminfo.semvmx       /* SEMVMX unused - user param */
 160 RO seminfo.semaem       /* SEMAEM unused - user param */
 161 #endif
 162
 163 static void
 164 seminit(void *dummy)
 165 {
 166         int i;
 167
 168         sem = kmalloc(sizeof(struct sem) * seminfo.semmns, M_SEM, M_WAITOK);
 169         if (sem == NULL)
 170                 panic("sem is NULL");
 171         sema = kmalloc(sizeof(struct semid_ds) * seminfo.semmni, M_SEM, M_WAITOK);
 172         if (sema == NULL)
 173                 panic("sema is NULL");
 174         semu = kmalloc(seminfo.semmnu * seminfo.semusz, M_SEM, M_WAITOK);
 175         if (semu == NULL)
 176                 panic("semu is NULL");
 177
 178         for (i = 0; i < seminfo.semmni; i++) {
 179                 sema[i].sem_base = 0;
 180                 sema[i].sem_perm.mode = 0;
 181         }
 182         for (i = 0; i < seminfo.semmnu; i++) {
 183                 struct sem_undo *suptr = SEMU(i);
 184                 suptr->un_proc = NULL;
 185         }
 186         semu_list = NULL;
 187 }
 188 SYSINIT(sysv_sem, SI_SUB_SYSV_SEM, SI_ORDER_FIRST, seminit, NULL)
 189
 190 /*
 191  * Entry point for all SEM calls
 192  *
 193  * semsys_args(int which, a2, a3, ...) (VARARGS)
 194  */
 195 int
 196 sys_semsys(struct semsys_args *uap)
 197 {
 198         struct proc *p = curproc;
 199         unsigned int which = (unsigned int)uap->which;
 200
 201         if (!jail_sysvipc_allowed && p->p_ucred->cr_prison != NULL)
 202                 return (ENOSYS);
 203
 204         if (which >= sizeof(semcalls)/sizeof(semcalls[0]))
 205                 return (EINVAL);
 206         bcopy(&uap->a2, &uap->which,
 207             sizeof(struct semsys_args) - offsetof(struct semsys_args, a2));
 208         return ((*semcalls[which])(uap));
 209 }
 210
 211 /*
 212  * Allocate a new sem_undo structure for a process
 213  * (returns ptr to structure or NULL if no more room)
 214  */
 215
 216 static struct sem_undo *
 217 semu_alloc(struct proc *p)
 218 {
 219         int i;
 220         struct sem_undo *suptr;
 221         struct sem_undo **supptr;
 222         int attempt;
 223
 224         /*
 225          * Try twice to allocate something.
 226          * (we'll purge any empty structures after the first pass so
 227          * two passes are always enough)
 228          */
 229
 230         for (attempt = 0; attempt < 2; attempt++) {
 231                 /*
 232                  * Look for a free structure.
 233                  * Fill it in and return it if we find one.
 234                  */
 235
 236                 for (i = 0; i < seminfo.semmnu; i++) {
 237                         suptr = SEMU(i);
 238                         if (suptr->un_proc == NULL) {
 239                                 suptr->un_next = semu_list;
 240                                 semu_list = suptr;
 241                                 suptr->un_cnt = 0;
 242                                 suptr->un_proc = p;
 243                                 return(suptr);
 244                         }
 245                 }
 246
 247                 /*
 248                  * We didn't find a free one, if this is the first attempt
 249                  * then try to free some structures.
 250                  */
 251
 252                 if (attempt == 0) {
 253                         /* All the structures are in use - try to free some */
 254                         int did_something = 0;
 255
 256                         supptr = &semu_list;
 257                         while ((suptr = *supptr) != NULL) {
 258                                 if (suptr->un_cnt == 0)  {
 259                                         suptr->un_proc = NULL;
 260                                         *supptr = suptr->un_next;
 261                                         did_something = 1;
 262                                 } else
 263                                         supptr = &(suptr->un_next);
 264                         }
 265
 266                         /* If we didn't free anything then just give-up */
 267                         if (!did_something)
 268                                 return(NULL);
 269                 } else {
 270                         /*
 271                          * The second pass failed even though we freed
 272                          * something after the first pass!
 273                          * This is IMPOSSIBLE!
 274                          */
 275                         panic("semu_alloc - second attempt failed");
 276                 }
 277         }
 278         return (NULL);
 279 }
 280
 281 /*
 282  * Adjust a particular entry for a particular proc
 283  */
 284
 285 static int
 286 semundo_adjust(struct proc *p, struct sem_undo **supptr, int semid, int semnum,
 287                int adjval)
 288 {
 289         struct sem_undo *suptr;
 290         struct undo *sunptr;
 291         int i;
 292
 293         /* Look for and remember the sem_undo if the caller doesn't provide
 294            it */
 295
 296         suptr = *supptr;
 297         if (suptr == NULL) {
 298                 for (suptr = semu_list; suptr != NULL;
 299                     suptr = suptr->un_next) {
 300                         if (suptr->un_proc == p) {
 301                                 *supptr = suptr;
 302                                 break;
 303                         }
 304                 }
 305                 if (suptr == NULL) {
 306                         if (adjval == 0)
 307                                 return(0);
 308                         suptr = semu_alloc(p);
 309                         if (suptr == NULL)
 310                                 return(ENOSPC);
 311                         *supptr = suptr;
 312                 }
 313         }
 314
 315         /*
 316          * Look for the requested entry and adjust it (delete if adjval becomes
 317          * 0).
 318          */
 319         sunptr = &suptr->un_ent[0];
 320         for (i = 0; i < suptr->un_cnt; i++, sunptr++) {
 321                 if (sunptr->un_id != semid || sunptr->un_num != semnum)
 322                         continue;
 323                 if (adjval == 0)
 324                         sunptr->un_adjval = 0;
 325                 else
 326                         sunptr->un_adjval += adjval;
 327                 if (sunptr->un_adjval == 0) {
 328                         suptr->un_cnt--;
 329                         if (i < suptr->un_cnt)
 330                                 suptr->un_ent[i] =
 331                                     suptr->un_ent[suptr->un_cnt];
 332                 }
 333                 return(0);
 334         }
 335
 336         /* Didn't find the right entry - create it */
 337         if (adjval == 0)
 338                 return(0);
 339         if (suptr->un_cnt != seminfo.semume) {
 340                 sunptr = &suptr->un_ent[suptr->un_cnt];
 341                 suptr->un_cnt++;
 342                 sunptr->un_adjval = adjval;
 343                 sunptr->un_id = semid; sunptr->un_num = semnum;
 344         } else
 345                 return(EINVAL);
 346         return(0);
 347 }
 348
 349 static void
 350 semundo_clear(int semid, int semnum)
 351 {
 352         struct sem_undo *suptr;
 353
 354         for (suptr = semu_list; suptr != NULL; suptr = suptr->un_next) {
 355                 struct undo *sunptr = &suptr->un_ent[0];
 356                 int i = 0;
 357
 358                 while (i < suptr->un_cnt) {
 359                         if (sunptr->un_id == semid) {
 360                                 if (semnum == -1 || sunptr->un_num == semnum) {
 361                                         suptr->un_cnt--;
 362                                         if (i < suptr->un_cnt) {
 363                                                 suptr->un_ent[i] =
 364                                                   suptr->un_ent[suptr->un_cnt];
 365                                                 continue;
 366                                         }
 367                                 }
 368                                 if (semnum != -1)
 369                                         break;
 370                         }
 371                         i++, sunptr++;
 372                 }
 373         }
 374 }
 375
 376 /*
 377  * Note that the user-mode half of this passes a union, not a pointer
 378  */
 379
 380 int
 381 sys___semctl(struct __semctl_args *uap)
 382 {
 383         struct proc *p = curproc;
 384         int semid = uap->semid;
 385         int semnum = uap->semnum;
 386         int cmd = uap->cmd;
 387         union semun *arg = uap->arg;
 388         union semun real_arg;
 389         struct ucred *cred = p->p_ucred;
 390         int i, rval, eval;
 391         struct semid_ds sbuf;
 392         struct semid_ds *semaptr;
 393
 394 #ifdef SEM_DEBUG
 395         kprintf("call to semctl(%d, %d, %d, 0x%x)\n", semid, semnum, cmd, arg);
 396 #endif
 397
 398         if (!jail_sysvipc_allowed && p->p_ucred->cr_prison != NULL)
 399                 return (ENOSYS);
 400
 401         semid = IPCID_TO_IX(semid);
 402         if (semid < 0 || semid >= seminfo.semmni)
 403                 return(EINVAL);
 404
 405         semaptr = &sema[semid];
 406         if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 ||
 407             semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid))
 408                 return(EINVAL);
 409
 410         eval = 0;
 411         rval = 0;
 412
 413         switch (cmd) {
 414         case IPC_RMID:
 415                 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_M)))
 416                         return(eval);
 417                 semaptr->sem_perm.cuid = cred->cr_uid;
 418                 semaptr->sem_perm.uid = cred->cr_uid;
 419                 semtot -= semaptr->sem_nsems;
 420                 for (i = semaptr->sem_base - sem; i < semtot; i++)
 421                         sem[i] = sem[i + semaptr->sem_nsems];
 422                 for (i = 0; i < seminfo.semmni; i++) {
 423                         if ((sema[i].sem_perm.mode & SEM_ALLOC) &&
 424                             sema[i].sem_base > semaptr->sem_base)
 425                                 sema[i].sem_base -= semaptr->sem_nsems;
 426                 }
 427                 semaptr->sem_perm.mode = 0;
 428                 semundo_clear(semid, -1);
 429                 wakeup((caddr_t)semaptr);
 430                 break;
 431
 432         case IPC_SET:
 433                 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_M)))
 434                         return(eval);
 435                 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
 436                         return(eval);
 437                 if ((eval = copyin(real_arg.buf, (caddr_t)&sbuf,
 438                     sizeof(sbuf))) != 0)
 439                         return(eval);
 440                 semaptr->sem_perm.uid = sbuf.sem_perm.uid;
 441                 semaptr->sem_perm.gid = sbuf.sem_perm.gid;
 442                 semaptr->sem_perm.mode = (semaptr->sem_perm.mode & ~0777) |
 443                     (sbuf.sem_perm.mode & 0777);
 444                 semaptr->sem_ctime = time_second;
 445                 break;
 446
 447         case IPC_STAT:
 448                 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R)))
 449                         return(eval);
 450                 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
 451                         return(eval);
 452                 eval = copyout((caddr_t)semaptr, real_arg.buf,
 453                     sizeof(struct semid_ds));
 454                 break;
 455
 456         case GETNCNT:
 457                 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R)))
 458                         return(eval);
 459                 if (semnum < 0 || semnum >= semaptr->sem_nsems)
 460                         return(EINVAL);
 461                 rval = semaptr->sem_base[semnum].semncnt;
 462                 break;
 463
 464         case GETPID:
 465                 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R)))
 466                         return(eval);
 467                 if (semnum < 0 || semnum >= semaptr->sem_nsems)
 468                         return(EINVAL);
 469                 rval = semaptr->sem_base[semnum].sempid;
 470                 break;
 471
 472         case GETVAL:
 473                 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R)))
 474                         return(eval);
 475                 if (semnum < 0 || semnum >= semaptr->sem_nsems)
 476                         return(EINVAL);
 477                 rval = semaptr->sem_base[semnum].semval;
 478                 break;
 479
 480         case GETALL:
 481                 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R)))
 482                         return(eval);
 483                 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
 484                         return(eval);
 485                 for (i = 0; i < semaptr->sem_nsems; i++) {
 486                         eval = copyout((caddr_t)&semaptr->sem_base[i].semval,
 487                             &real_arg.array[i], sizeof(real_arg.array[0]));
 488                         if (eval != 0)
 489                                 break;
 490                 }
 491                 break;
 492
 493         case GETZCNT:
 494                 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R)))
 495                         return(eval);
 496                 if (semnum < 0 || semnum >= semaptr->sem_nsems)
 497                         return(EINVAL);
 498                 rval = semaptr->sem_base[semnum].semzcnt;
 499                 break;
 500
 501         case SETVAL:
 502                 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_W)))
 503                         return(eval);
 504                 if (semnum < 0 || semnum >= semaptr->sem_nsems)
 505                         return(EINVAL);
 506                 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
 507                         return(eval);
 508                 semaptr->sem_base[semnum].semval = real_arg.val;
 509                 semundo_clear(semid, semnum);
 510                 wakeup((caddr_t)semaptr);
 511                 break;
 512
 513         case SETALL:
 514                 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_W)))
 515                         return(eval);
 516                 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
 517                         return(eval);
 518                 for (i = 0; i < semaptr->sem_nsems; i++) {
 519                         eval = copyin(&real_arg.array[i],
 520                             (caddr_t)&semaptr->sem_base[i].semval,
 521                             sizeof(real_arg.array[0]));
 522                         if (eval != 0)
 523                                 break;
 524                 }
 525                 semundo_clear(semid, -1);
 526                 wakeup((caddr_t)semaptr);
 527                 break;
 528
 529         default:
 530                 return(EINVAL);
 531         }
 532
 533         if (eval == 0)
 534                 uap->sysmsg_result = rval;
 535         return(eval);
 536 }
 537
 538 int
 539 sys_semget(struct semget_args *uap)
 540 {
 541         struct proc *p = curproc;
 542         int semid, eval;
 543         int key = uap->key;
 544         int nsems = uap->nsems;
 545         int semflg = uap->semflg;
 546         struct ucred *cred = p->p_ucred;
 547
 548 #ifdef SEM_DEBUG
 549         kprintf("semget(0x%x, %d, 0%o)\n", key, nsems, semflg);
 550 #endif
 551
 552         if (!jail_sysvipc_allowed && p->p_ucred->cr_prison != NULL)
 553                 return (ENOSYS);
 554
 555         if (key != IPC_PRIVATE) {
 556                 for (semid = 0; semid < seminfo.semmni; semid++) {
 557                         if ((sema[semid].sem_perm.mode & SEM_ALLOC) &&
 558                             sema[semid].sem_perm.key == key)
 559                                 break;
 560                 }
 561                 if (semid < seminfo.semmni) {
 562 #ifdef SEM_DEBUG
 563                         kprintf("found public key\n");
 564 #endif
 565                         if ((eval = ipcperm(p, &sema[semid].sem_perm,
 566                             semflg & 0700)))
 567                                 return(eval);
 568                         if (nsems > 0 && sema[semid].sem_nsems < nsems) {
 569 #ifdef SEM_DEBUG
 570                                 kprintf("too small\n");
 571 #endif
 572                                 return(EINVAL);
 573                         }
 574                         if ((semflg & IPC_CREAT) && (semflg & IPC_EXCL)) {
 575 #ifdef SEM_DEBUG
 576                                 kprintf("not exclusive\n");
 577 #endif
 578                                 return(EEXIST);
 579                         }
 580                         goto found;
 581                 }
 582         }
 583
 584 #ifdef SEM_DEBUG
 585         kprintf("need to allocate the semid_ds\n");
 586 #endif
 587         if (key == IPC_PRIVATE || (semflg & IPC_CREAT)) {
 588                 if (nsems <= 0 || nsems > seminfo.semmsl) {
 589 #ifdef SEM_DEBUG
 590                         kprintf("nsems out of range (0<%d<=%d)\n", nsems,
 591                             seminfo.semmsl);
 592 #endif
 593                         return(EINVAL);
 594                 }
 595                 if (nsems > seminfo.semmns - semtot) {
 596 #ifdef SEM_DEBUG
 597                         kprintf("not enough semaphores left (need %d, got %d)\n",
 598                             nsems, seminfo.semmns - semtot);
 599 #endif
 600                         return(ENOSPC);
 601                 }
 602                 for (semid = 0; semid < seminfo.semmni; semid++) {
 603                         if ((sema[semid].sem_perm.mode & SEM_ALLOC) == 0)
 604                                 break;
 605                 }
 606                 if (semid == seminfo.semmni) {
 607 #ifdef SEM_DEBUG
 608                         kprintf("no more semid_ds's available\n");
 609 #endif
 610                         return(ENOSPC);
 611                 }
 612 #ifdef SEM_DEBUG
 613                 kprintf("semid %d is available\n", semid);
 614 #endif
 615                 sema[semid].sem_perm.key = key;
 616                 sema[semid].sem_perm.cuid = cred->cr_uid;
 617                 sema[semid].sem_perm.uid = cred->cr_uid;
 618                 sema[semid].sem_perm.cgid = cred->cr_gid;
 619                 sema[semid].sem_perm.gid = cred->cr_gid;
 620                 sema[semid].sem_perm.mode = (semflg & 0777) | SEM_ALLOC;
 621                 sema[semid].sem_perm.seq =
 622                     (sema[semid].sem_perm.seq + 1) & 0x7fff;
 623                 sema[semid].sem_nsems = nsems;
 624                 sema[semid].sem_otime = 0;
 625                 sema[semid].sem_ctime = time_second;
 626                 sema[semid].sem_base = &sem[semtot];
 627                 semtot += nsems;
 628                 bzero(sema[semid].sem_base,
 629                     sizeof(sema[semid].sem_base[0])*nsems);
 630 #ifdef SEM_DEBUG
 631                 kprintf("sembase = 0x%x, next = 0x%x\n", sema[semid].sem_base,
 632                     &sem[semtot]);
 633 #endif
 634         } else {
 635 #ifdef SEM_DEBUG
 636                 kprintf("didn't find it and wasn't asked to create it\n");
 637 #endif
 638                 return(ENOENT);
 639         }
 640
 641 found:
 642         uap->sysmsg_result = IXSEQ_TO_IPCID(semid, sema[semid].sem_perm);
 643         return(0);
 644 }
 645
 646 int
 647 sys_semop(struct semop_args *uap)
 648 {
 649         struct proc *p = curproc;
 650         int semid = uap->semid;
 651         u_int nsops = uap->nsops;
 652         struct sembuf sops[MAX_SOPS];
 653         struct semid_ds *semaptr;
 654         struct sembuf *sopptr;
 655         struct sem *semptr;
 656         struct sem_undo *suptr = NULL;
 657         int i, j, eval;
 658         int do_wakeup, do_undos;
 659
 660 #ifdef SEM_DEBUG
 661         kprintf("call to semop(%d, 0x%x, %u)\n", semid, sops, nsops);
 662 #endif
 663
 664         if (!jail_sysvipc_allowed && p->p_ucred->cr_prison != NULL)
 665                 return (ENOSYS);
 666
 667         semid = IPCID_TO_IX(semid);     /* Convert back to zero origin */
 668
 669         if (semid < 0 || semid >= seminfo.semmni)
 670                 return(EINVAL);
 671
 672         semaptr = &sema[semid];
 673         if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0)
 674                 return(EINVAL);
 675         if (semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid))
 676                 return(EINVAL);
 677
 678         if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_W))) {
 679 #ifdef SEM_DEBUG
 680                 kprintf("eval = %d from ipaccess\n", eval);
 681 #endif
 682                 return(eval);
 683         }
 684
 685         if (nsops > MAX_SOPS) {
 686 #ifdef SEM_DEBUG
 687                 kprintf("too many sops (max=%d, nsops=%u)\n", MAX_SOPS, nsops);
 688 #endif
 689                 return(E2BIG);
 690         }
 691
 692         if ((eval = copyin(uap->sops, &sops, nsops * sizeof(sops[0]))) != 0) {
 693 #ifdef SEM_DEBUG
 694                 kprintf("eval = %d from copyin(%08x, %08x, %u)\n", eval,
 695                     uap->sops, &sops, nsops * sizeof(sops[0]));
 696 #endif
 697                 return(eval);
 698         }
 699
 700         /*
 701          * Loop trying to satisfy the vector of requests.
 702          * If we reach a point where we must wait, any requests already
 703          * performed are rolled back and we go to sleep until some other
 704          * process wakes us up.  At this point, we start all over again.
 705          *
 706          * This ensures that from the perspective of other tasks, a set
 707          * of requests is atomic (never partially satisfied).
 708          */
 709         do_undos = 0;
 710
 711         for (;;) {
 712                 do_wakeup = 0;
 713
 714                 for (i = 0; i < nsops; i++) {
 715                         sopptr = &sops[i];
 716
 717                         if (sopptr->sem_num >= semaptr->sem_nsems)
 718                                 return(EFBIG);
 719
 720                         semptr = &semaptr->sem_base[sopptr->sem_num];
 721
 722 #ifdef SEM_DEBUG
 723                         kprintf("semop:  semaptr=%x, sem_base=%x, semptr=%x, sem[%d]=%d : op=%d, flag=%s\n",
 724                             semaptr, semaptr->sem_base, semptr,
 725                             sopptr->sem_num, semptr->semval, sopptr->sem_op,
 726                             (sopptr->sem_flg & IPC_NOWAIT) ? "nowait" : "wait");
 727 #endif
 728
 729                         if (sopptr->sem_op < 0) {
 730                                 if (semptr->semval + sopptr->sem_op < 0) {
 731 #ifdef SEM_DEBUG
 732                                         kprintf("semop:  can't do it now\n");
 733 #endif
 734                                         break;
 735                                 } else {
 736                                         semptr->semval += sopptr->sem_op;
 737                                         if (semptr->semval == 0 &&
 738                                             semptr->semzcnt > 0)
 739                                                 do_wakeup = 1;
 740                                 }
 741                                 if (sopptr->sem_flg & SEM_UNDO)
 742                                         do_undos = 1;
 743                         } else if (sopptr->sem_op == 0) {
 744                                 if (semptr->semval > 0) {
 745 #ifdef SEM_DEBUG
 746                                         kprintf("semop:  not zero now\n");
 747 #endif
 748                                         break;
 749                                 }
 750                         } else {
 751                                 if (semptr->semncnt > 0)
 752                                         do_wakeup = 1;
 753                                 semptr->semval += sopptr->sem_op;
 754                                 if (sopptr->sem_flg & SEM_UNDO)
 755                                         do_undos = 1;
 756                         }
 757                 }
 758
 759                 /*
 760                  * Did we get through the entire vector?
 761                  */
 762                 if (i >= nsops)
 763                         goto done;
 764
 765                 /*
 766                  * No ... rollback anything that we've already done
 767                  */
 768 #ifdef SEM_DEBUG
 769                 kprintf("semop:  rollback 0 through %d\n", i-1);
 770 #endif
 771                 for (j = 0; j < i; j++)
 772                         semaptr->sem_base[sops[j].sem_num].semval -=
 773                             sops[j].sem_op;
 774
 775                 /*
 776                  * If the request that we couldn't satisfy has the
 777                  * NOWAIT flag set then return with EAGAIN.
 778                  */
 779                 if (sopptr->sem_flg & IPC_NOWAIT)
 780                         return(EAGAIN);
 781
 782                 if (sopptr->sem_op == 0)
 783                         semptr->semzcnt++;
 784                 else
 785                         semptr->semncnt++;
 786
 787 #ifdef SEM_DEBUG
 788                 kprintf("semop:  good night!\n");
 789 #endif
 790                 eval = tsleep((caddr_t)semaptr, PCATCH, "semwait", 0);
 791 #ifdef SEM_DEBUG
 792                 kprintf("semop:  good morning (eval=%d)!\n", eval);
 793 #endif
 794
 795                 suptr = NULL;   /* sem_undo may have been reallocated */
 796
 797                 /* return code is checked below, after sem[nz]cnt-- */
 798
 799                 /*
 800                  * Make sure that the semaphore still exists
 801                  */
 802                 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 ||
 803                     semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid))
 804                         return(EIDRM);
 805
 806                 /*
 807                  * The semaphore is still alive.  Readjust the count of
 808                  * waiting processes.
 809                  */
 810                 if (sopptr->sem_op == 0)
 811                         semptr->semzcnt--;
 812                 else
 813                         semptr->semncnt--;
 814
 815                 /*
 816                  * Is it really morning, or was our sleep interrupted?
 817                  * (Delayed check of msleep() return code because we
 818                  * need to decrement sem[nz]cnt either way.)
 819                  */
 820                 if (eval != 0)
 821                         return(EINTR);
 822 #ifdef SEM_DEBUG
 823                 kprintf("semop:  good morning!\n");
 824 #endif
 825         }
 826
 827 done:
 828         /*
 829          * Process any SEM_UNDO requests.
 830          */
 831         if (do_undos) {
 832                 for (i = 0; i < nsops; i++) {
 833                         /*
 834                          * We only need to deal with SEM_UNDO's for non-zero
 835                          * op's.
 836                          */
 837                         int adjval;
 838
 839                         if ((sops[i].sem_flg & SEM_UNDO) == 0)
 840                                 continue;
 841                         adjval = sops[i].sem_op;
 842                         if (adjval == 0)
 843                                 continue;
 844                         eval = semundo_adjust(p, &suptr, semid,
 845                             sops[i].sem_num, -adjval);
 846                         if (eval == 0)
 847                                 continue;
 848
 849                         /*
 850                          * Oh-Oh!  We ran out of either sem_undo's or undo's.
 851                          * Rollback the adjustments to this point and then
 852                          * rollback the semaphore ups and down so we can return
 853                          * with an error with all structures restored.  We
 854                          * rollback the undo's in the exact reverse order that
 855                          * we applied them.  This guarantees that we won't run
 856                          * out of space as we roll things back out.
 857                          */
 858                         for (j = i - 1; j >= 0; j--) {
 859                                 if ((sops[j].sem_flg & SEM_UNDO) == 0)
 860                                         continue;
 861                                 adjval = sops[j].sem_op;
 862                                 if (adjval == 0)
 863                                         continue;
 864                                 if (semundo_adjust(p, &suptr, semid,
 865                                     sops[j].sem_num, adjval) != 0)
 866                                         panic("semop - can't undo undos");
 867                         }
 868
 869                         for (j = 0; j < nsops; j++)
 870                                 semaptr->sem_base[sops[j].sem_num].semval -=
 871                                     sops[j].sem_op;
 872
 873 #ifdef SEM_DEBUG
 874                         kprintf("eval = %d from semundo_adjust\n", eval);
 875 #endif
 876                         return(eval);
 877                 } /* loop through the sops */
 878         } /* if (do_undos) */
 879
 880         /* We're definitely done - set the sempid's */
 881         for (i = 0; i < nsops; i++) {
 882                 sopptr = &sops[i];
 883                 semptr = &semaptr->sem_base[sopptr->sem_num];
 884                 semptr->sempid = p->p_pid;
 885         }
 886
 887         /* Do a wakeup if any semaphore was up'd. */
 888         if (do_wakeup) {
 889 #ifdef SEM_DEBUG
 890                 kprintf("semop:  doing wakeup\n");
 891 #endif
 892                 wakeup((caddr_t)semaptr);
 893 #ifdef SEM_DEBUG
 894                 kprintf("semop:  back from wakeup\n");
 895 #endif
 896         }
 897 #ifdef SEM_DEBUG
 898         kprintf("semop:  done\n");
 899 #endif
 900         uap->sysmsg_result = 0;
 901         return(0);
 902 }
 903
 904 /*
 905  * Go through the undo structures for this process and apply the adjustments to
 906  * semaphores.
 907  */
 908 void
 909 semexit(struct proc *p)
 910 {
 911         struct sem_undo *suptr;
 912         struct sem_undo **supptr;
 913         int did_something;
 914
 915         did_something = 0;
 916
 917         /*
 918          * Go through the chain of undo vectors looking for one
 919          * associated with this process.
 920          */
 921
 922         for (supptr = &semu_list; (suptr = *supptr) != NULL;
 923             supptr = &suptr->un_next) {
 924                 if (suptr->un_proc == p)
 925                         break;
 926         }
 927
 928         if (suptr == NULL)
 929                 return;
 930
 931 #ifdef SEM_DEBUG
 932         kprintf("proc @%08x has undo structure with %d entries\n", p,
 933             suptr->un_cnt);
 934 #endif
 935
 936         /*
 937          * If there are any active undo elements then process them.
 938          */
 939         if (suptr->un_cnt > 0) {
 940                 int ix;
 941
 942                 for (ix = 0; ix < suptr->un_cnt; ix++) {
 943                         int semid = suptr->un_ent[ix].un_id;
 944                         int semnum = suptr->un_ent[ix].un_num;
 945                         int adjval = suptr->un_ent[ix].un_adjval;
 946                         struct semid_ds *semaptr;
 947
 948                         semaptr = &sema[semid];
 949                         if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0)
 950                                 panic("semexit - semid not allocated");
 951                         if (semnum >= semaptr->sem_nsems)
 952                                 panic("semexit - semnum out of range");
 953
 954 #ifdef SEM_DEBUG
 955                         kprintf("semexit:  %08x id=%d num=%d(adj=%d) ; sem=%d\n",
 956                             suptr->un_proc, suptr->un_ent[ix].un_id,
 957                             suptr->un_ent[ix].un_num,
 958                             suptr->un_ent[ix].un_adjval,
 959                             semaptr->sem_base[semnum].semval);
 960 #endif
 961
 962                         if (adjval < 0) {
 963                                 if (semaptr->sem_base[semnum].semval < -adjval)
 964                                         semaptr->sem_base[semnum].semval = 0;
 965                                 else
 966                                         semaptr->sem_base[semnum].semval +=
 967                                             adjval;
 968                         } else
 969                                 semaptr->sem_base[semnum].semval += adjval;
 970
 971                         wakeup((caddr_t)semaptr);
 972 #ifdef SEM_DEBUG
 973                         kprintf("semexit:  back from wakeup\n");
 974 #endif
 975                 }
 976         }
 977
 978         /*
 979          * Deallocate the undo vector.
 980          */
 981 #ifdef SEM_DEBUG
 982         kprintf("removing vector\n");
 983 #endif
 984         suptr->un_proc = NULL;
 985         *supptr = suptr->un_next;
 986 }