/* $NetBSD: sysv_sem.c,v 1.47 2003/06/29 22:31:27 fvdl Exp $ */ /*- * Copyright (c) 1999 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility, * NASA Ames Research Center. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the NetBSD * Foundation, Inc. and its contributors. * 4. Neither the name of The NetBSD Foundation nor the names of its * contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ /* * Implementation of SVID semaphores * * Author: Daniel Boulet * * This software is provided ``AS IS'' without any warranties of any kind. */ #include __KERNEL_RCSID(0, "$NetBSD: sysv_sem.c,v 1.47 2003/06/29 22:31:27 fvdl Exp $"); #define SYSVSEM #include #include #include #include #include /* XXX for */ #include #include int semtot = 0; struct semid_ds *sema; /* semaphore id pool */ struct __sem *sem; /* semaphore pool */ struct sem_undo *semu_list; /* list of active undo structures */ int *semu; /* undo structure pool */ #ifdef SEM_DEBUG #define SEM_PRINTF(a) printf a #else #define SEM_PRINTF(a) #endif struct sem_undo *semu_alloc __P((struct proc *)); int semundo_adjust __P((struct proc *, struct sem_undo **, int, int, int)); void semundo_clear __P((int, int)); /* * XXXSMP Once we go MP, there needs to be a lock for the semaphore system. * Until then, we're saved by being a non-preemptive kernel. */ void seminit() { int i; if (sema == NULL) panic("sema is NULL"); if (semu == NULL) panic("semu is NULL"); for (i = 0; i < seminfo.semmni; i++) { sema[i]._sem_base = 0; sema[i].sem_perm.mode = 0; } for (i = 0; i < seminfo.semmnu; i++) { struct sem_undo *suptr = SEMU(i); suptr->un_proc = NULL; } semu_list = NULL; exithook_establish(semexit, NULL); } /* * Placebo. */ int sys_semconfig(l, v, retval) struct lwp *l; void *v; register_t *retval; { *retval = 0; return 0; } /* * Allocate a new sem_undo structure for a process * (returns ptr to structure or NULL if no more room) */ struct sem_undo * semu_alloc(p) struct proc *p; { int i; struct sem_undo *suptr; struct sem_undo **supptr; int attempt; /* * Try twice to allocate something. * (we'll purge any empty structures after the first pass so * two passes are always enough) */ for (attempt = 0; attempt < 2; attempt++) { /* * Look for a free structure. * Fill it in and return it if we find one. */ for (i = 0; i < seminfo.semmnu; i++) { suptr = SEMU(i); if (suptr->un_proc == NULL) { suptr->un_next = semu_list; semu_list = suptr; suptr->un_cnt = 0; suptr->un_proc = p; return(suptr); } } /* * We didn't find a free one, if this is the first attempt * then try to free some structures. */ if (attempt == 0) { /* All the structures are in use - try to free some */ int did_something = 0; supptr = &semu_list; while ((suptr = *supptr) != NULL) { if (suptr->un_cnt == 0) { suptr->un_proc = NULL; *supptr = suptr->un_next; did_something = 1; } else supptr = &(suptr->un_next); } /* If we didn't free anything then just give-up */ if (!did_something) return(NULL); } else { /* * The second pass failed even though we freed * something after the first pass! * This is IMPOSSIBLE! */ panic("semu_alloc - second attempt failed"); } } return NULL; } /* * Adjust a particular entry for a particular proc */ int semundo_adjust(p, supptr, semid, semnum, adjval) struct proc *p; struct sem_undo **supptr; int semid, semnum; int adjval; { struct sem_undo *suptr; struct undo *sunptr; int i; /* Look for and remember the sem_undo if the caller doesn't provide it */ suptr = *supptr; if (suptr == NULL) { for (suptr = semu_list; suptr != NULL; suptr = suptr->un_next) { if (suptr->un_proc == p) { *supptr = suptr; break; } } if (suptr == NULL) { if (adjval == 0) return(0); suptr = semu_alloc(p); if (suptr == NULL) return(ENOSPC); *supptr = suptr; } } /* * Look for the requested entry and adjust it (delete if adjval becomes * 0). */ sunptr = &suptr->un_ent[0]; for (i = 0; i < suptr->un_cnt; i++, sunptr++) { if (sunptr->un_id != semid || sunptr->un_num != semnum) continue; if (adjval == 0) sunptr->un_adjval = 0; else sunptr->un_adjval += adjval; if (sunptr->un_adjval == 0) { suptr->un_cnt--; if (i < suptr->un_cnt) suptr->un_ent[i] = suptr->un_ent[suptr->un_cnt]; } return(0); } /* Didn't find the right entry - create it */ if (adjval == 0) return(0); if (suptr->un_cnt == SEMUME) return(EINVAL); sunptr = &suptr->un_ent[suptr->un_cnt]; suptr->un_cnt++; sunptr->un_adjval = adjval; sunptr->un_id = semid; sunptr->un_num = semnum; return(0); } void semundo_clear(semid, semnum) int semid, semnum; { struct sem_undo *suptr; for (suptr = semu_list; suptr != NULL; suptr = suptr->un_next) { struct undo *sunptr; int i; sunptr = &suptr->un_ent[0]; for (i = 0; i < suptr->un_cnt; i++, sunptr++) { if (sunptr->un_id == semid) { if (semnum == -1 || sunptr->un_num == semnum) { suptr->un_cnt--; if (i < suptr->un_cnt) { suptr->un_ent[i] = suptr->un_ent[suptr->un_cnt]; i--, sunptr--; } } if (semnum != -1) break; } } } } int sys_____semctl13(l, v, retval) struct lwp *l; void *v; register_t *retval; { struct sys_____semctl13_args /* { syscallarg(int) semid; syscallarg(int) semnum; syscallarg(int) cmd; syscallarg(union __semun *) arg; } */ *uap = v; struct proc *p = l->l_proc; struct semid_ds sembuf; int cmd, error; void *pass_arg; union __semun karg; cmd = SCARG(uap, cmd); switch (cmd) { case IPC_SET: case IPC_STAT: pass_arg = &sembuf; break; case GETALL: case SETVAL: case SETALL: pass_arg = &karg; break; default: pass_arg = NULL; break; } if (pass_arg) { error = copyin(SCARG(uap, arg), &karg, sizeof(karg)); if (error) return error; if (cmd == IPC_SET) { error = copyin(karg.buf, &sembuf, sizeof(sembuf)); if (error) return (error); } } error = semctl1(p, SCARG(uap, semid), SCARG(uap, semnum), cmd, pass_arg, retval); if (error == 0 && cmd == IPC_STAT) error = copyout(&sembuf, karg.buf, sizeof(sembuf)); return (error); } int semctl1(p, semid, semnum, cmd, v, retval) struct proc *p; int semid, semnum, cmd; void *v; register_t *retval; { struct ucred *cred = p->p_ucred; union __semun *arg = v; struct semid_ds *sembuf = v, *semaptr; int i, error, ix; SEM_PRINTF(("call to semctl(%d, %d, %d, %p)\n", semid, semnum, cmd, v)); ix = IPCID_TO_IX(semid); if (ix < 0 || ix >= seminfo.semmsl) return (EINVAL); semaptr = &sema[ix]; if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 || semaptr->sem_perm._seq != IPCID_TO_SEQ(semid)) return (EINVAL); switch (cmd) { case IPC_RMID: if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_M)) != 0) return (error); semaptr->sem_perm.cuid = cred->cr_uid; semaptr->sem_perm.uid = cred->cr_uid; semtot -= semaptr->sem_nsems; for (i = semaptr->_sem_base - sem; i < semtot; i++) sem[i] = sem[i + semaptr->sem_nsems]; for (i = 0; i < seminfo.semmni; i++) { if ((sema[i].sem_perm.mode & SEM_ALLOC) && sema[i]._sem_base > semaptr->_sem_base) sema[i]._sem_base -= semaptr->sem_nsems; } semaptr->sem_perm.mode = 0; semundo_clear(ix, -1); wakeup(semaptr); break; case IPC_SET: if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_M))) return (error); semaptr->sem_perm.uid = sembuf->sem_perm.uid; semaptr->sem_perm.gid = sembuf->sem_perm.gid; semaptr->sem_perm.mode = (semaptr->sem_perm.mode & ~0777) | (sembuf->sem_perm.mode & 0777); semaptr->sem_ctime = time.tv_sec; break; case IPC_STAT: if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R))) return (error); memcpy(sembuf, semaptr, sizeof(struct semid_ds)); break; case GETNCNT: if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R))) return (error); if (semnum < 0 || semnum >= semaptr->sem_nsems) return (EINVAL); *retval = semaptr->_sem_base[semnum].semncnt; break; case GETPID: if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R))) return (error); if (semnum < 0 || semnum >= semaptr->sem_nsems) return (EINVAL); *retval = semaptr->_sem_base[semnum].sempid; break; case GETVAL: if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R))) return (error); if (semnum < 0 || semnum >= semaptr->sem_nsems) return (EINVAL); *retval = semaptr->_sem_base[semnum].semval; break; case GETALL: if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R))) return (error); for (i = 0; i < semaptr->sem_nsems; i++) { error = copyout(&semaptr->_sem_base[i].semval, &arg->array[i], sizeof(arg->array[i])); if (error != 0) break; } break; case GETZCNT: if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R))) return (error); if (semnum < 0 || semnum >= semaptr->sem_nsems) return (EINVAL); *retval = semaptr->_sem_base[semnum].semzcnt; break; case SETVAL: if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_W))) return (error); if (semnum < 0 || semnum >= semaptr->sem_nsems) return (EINVAL); semaptr->_sem_base[semnum].semval = arg->val; semundo_clear(ix, semnum); wakeup(semaptr); break; case SETALL: if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_W))) return (error); for (i = 0; i < semaptr->sem_nsems; i++) { error = copyin(&arg->array[i], &semaptr->_sem_base[i].semval, sizeof(arg->array[i])); if (error != 0) break; } semundo_clear(ix, -1); wakeup(semaptr); break; default: return (EINVAL); } return (error); } int sys_semget(l, v, retval) struct lwp *l; void *v; register_t *retval; { struct sys_semget_args /* { syscallarg(key_t) key; syscallarg(int) nsems; syscallarg(int) semflg; } */ *uap = v; int semid, eval; int key = SCARG(uap, key); int nsems = SCARG(uap, nsems); int semflg = SCARG(uap, semflg); struct ucred *cred = l->l_proc->p_ucred; SEM_PRINTF(("semget(0x%x, %d, 0%o)\n", key, nsems, semflg)); if (key != IPC_PRIVATE) { for (semid = 0; semid < seminfo.semmni; semid++) { if ((sema[semid].sem_perm.mode & SEM_ALLOC) && sema[semid].sem_perm._key == key) break; } if (semid < seminfo.semmni) { SEM_PRINTF(("found public key\n")); if ((eval = ipcperm(cred, &sema[semid].sem_perm, semflg & 0700))) return(eval); if (nsems > 0 && sema[semid].sem_nsems < nsems) { SEM_PRINTF(("too small\n")); return(EINVAL); } if ((semflg & IPC_CREAT) && (semflg & IPC_EXCL)) { SEM_PRINTF(("not exclusive\n")); return(EEXIST); } goto found; } } SEM_PRINTF(("need to allocate the semid_ds\n")); if (key == IPC_PRIVATE || (semflg & IPC_CREAT)) { if (nsems <= 0 || nsems > seminfo.semmsl) { SEM_PRINTF(("nsems out of range (0<%d<=%d)\n", nsems, seminfo.semmsl)); return(EINVAL); } if (nsems > seminfo.semmns - semtot) { SEM_PRINTF(("not enough semaphores left (need %d, got %d)\n", nsems, seminfo.semmns - semtot)); return(ENOSPC); } for (semid = 0; semid < seminfo.semmni; semid++) { if ((sema[semid].sem_perm.mode & SEM_ALLOC) == 0) break; } if (semid == seminfo.semmni) { SEM_PRINTF(("no more semid_ds's available\n")); return(ENOSPC); } SEM_PRINTF(("semid %d is available\n", semid)); sema[semid].sem_perm._key = key; sema[semid].sem_perm.cuid = cred->cr_uid; sema[semid].sem_perm.uid = cred->cr_uid; sema[semid].sem_perm.cgid = cred->cr_gid; sema[semid].sem_perm.gid = cred->cr_gid; sema[semid].sem_perm.mode = (semflg & 0777) | SEM_ALLOC; sema[semid].sem_perm._seq = (sema[semid].sem_perm._seq + 1) & 0x7fff; sema[semid].sem_nsems = nsems; sema[semid].sem_otime = 0; sema[semid].sem_ctime = time.tv_sec; sema[semid]._sem_base = &sem[semtot]; semtot += nsems; memset(sema[semid]._sem_base, 0, sizeof(sema[semid]._sem_base[0])*nsems); SEM_PRINTF(("sembase = %p, next = %p\n", sema[semid]._sem_base, &sem[semtot])); } else { SEM_PRINTF(("didn't find it and wasn't asked to create it\n")); return(ENOENT); } found: *retval = IXSEQ_TO_IPCID(semid, sema[semid].sem_perm); return(0); } int sys_semop(l, v, retval) struct lwp *l; void *v; register_t *retval; { struct sys_semop_args /* { syscallarg(int) semid; syscallarg(struct sembuf *) sops; syscallarg(size_t) nsops; } */ *uap = v; struct proc *p = l->l_proc; int semid = SCARG(uap, semid); size_t nsops = SCARG(uap, nsops); struct sembuf sops[MAX_SOPS]; struct semid_ds *semaptr; struct sembuf *sopptr = NULL; struct __sem *semptr = NULL; struct sem_undo *suptr = NULL; struct ucred *cred = p->p_ucred; int i, j, eval; int do_wakeup, do_undos; SEM_PRINTF(("call to semop(%d, %p, %lld)\n", semid, sops, (long long)nsops)); semid = IPCID_TO_IX(semid); /* Convert back to zero origin */ if (semid < 0 || semid >= seminfo.semmsl) return(EINVAL); semaptr = &sema[semid]; if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 || semaptr->sem_perm._seq != IPCID_TO_SEQ(SCARG(uap, semid))) return(EINVAL); if ((eval = ipcperm(cred, &semaptr->sem_perm, IPC_W))) { SEM_PRINTF(("eval = %d from ipaccess\n", eval)); return(eval); } if (nsops > MAX_SOPS) { SEM_PRINTF(("too many sops (max=%d, nsops=%lld)\n", MAX_SOPS, (long long)nsops)); return(E2BIG); } if ((eval = copyin(SCARG(uap, sops), sops, nsops * sizeof(sops[0]))) != 0) { SEM_PRINTF(("eval = %d from copyin(%p, %p, %lld)\n", eval, SCARG(uap, sops), &sops, (long long)(nsops * sizeof(sops[0])))); return(eval); } /* * Loop trying to satisfy the vector of requests. * If we reach a point where we must wait, any requests already * performed are rolled back and we go to sleep until some other * process wakes us up. At this point, we start all over again. * * This ensures that from the perspective of other tasks, a set * of requests is atomic (never partially satisfied). */ do_undos = 0; for (;;) { do_wakeup = 0; for (i = 0; i < nsops; i++) { sopptr = &sops[i]; if (sopptr->sem_num >= semaptr->sem_nsems) return(EFBIG); semptr = &semaptr->_sem_base[sopptr->sem_num]; SEM_PRINTF(("semop: semaptr=%p, sem_base=%p, semptr=%p, sem[%d]=%d : op=%d, flag=%s\n", semaptr, semaptr->_sem_base, semptr, sopptr->sem_num, semptr->semval, sopptr->sem_op, (sopptr->sem_flg & IPC_NOWAIT) ? "nowait" : "wait")); if (sopptr->sem_op < 0) { if ((int)(semptr->semval + sopptr->sem_op) < 0) { SEM_PRINTF(("semop: can't do it now\n")); break; } else { semptr->semval += sopptr->sem_op; if (semptr->semval == 0 && semptr->semzcnt > 0) do_wakeup = 1; } if (sopptr->sem_flg & SEM_UNDO) do_undos = 1; } else if (sopptr->sem_op == 0) { if (semptr->semval > 0) { SEM_PRINTF(("semop: not zero now\n")); break; } } else { if (semptr->semncnt > 0) do_wakeup = 1; semptr->semval += sopptr->sem_op; if (sopptr->sem_flg & SEM_UNDO) do_undos = 1; } } /* * Did we get through the entire vector? */ if (i >= nsops) goto done; /* * No ... rollback anything that we've already done */ SEM_PRINTF(("semop: rollback 0 through %d\n", i-1)); for (j = 0; j < i; j++) semaptr->_sem_base[sops[j].sem_num].semval -= sops[j].sem_op; /* * If the request that we couldn't satisfy has the * NOWAIT flag set then return with EAGAIN. */ if (sopptr->sem_flg & IPC_NOWAIT) return(EAGAIN); if (sopptr->sem_op == 0) semptr->semzcnt++; else semptr->semncnt++; SEM_PRINTF(("semop: good night!\n")); eval = tsleep((caddr_t)semaptr, (PZERO - 4) | PCATCH, "semwait", 0); SEM_PRINTF(("semop: good morning (eval=%d)!\n", eval)); suptr = NULL; /* sem_undo may have been reallocated */ if (eval != 0) return(EINTR); SEM_PRINTF(("semop: good morning!\n")); /* * Make sure that the semaphore still exists */ if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 || semaptr->sem_perm._seq != IPCID_TO_SEQ(SCARG(uap, semid))) { /* The man page says to return EIDRM. */ /* Unfortunately, BSD doesn't define that code! */ #ifdef EIDRM return(EIDRM); #else return(EINVAL); #endif } /* * The semaphore is still alive. Readjust the count of * waiting processes. */ if (sopptr->sem_op == 0) semptr->semzcnt--; else semptr->semncnt--; } done: /* * Process any SEM_UNDO requests. */ if (do_undos) { for (i = 0; i < nsops; i++) { /* * We only need to deal with SEM_UNDO's for non-zero * op's. */ int adjval; if ((sops[i].sem_flg & SEM_UNDO) == 0) continue; adjval = sops[i].sem_op; if (adjval == 0) continue; eval = semundo_adjust(p, &suptr, semid, sops[i].sem_num, -adjval); if (eval == 0) continue; /* * Oh-Oh! We ran out of either sem_undo's or undo's. * Rollback the adjustments to this point and then * rollback the semaphore ups and down so we can return * with an error with all structures restored. We * rollback the undo's in the exact reverse order that * we applied them. This guarantees that we won't run * out of space as we roll things back out. */ for (j = i - 1; j >= 0; j--) { if ((sops[j].sem_flg & SEM_UNDO) == 0) continue; adjval = sops[j].sem_op; if (adjval == 0) continue; if (semundo_adjust(p, &suptr, semid, sops[j].sem_num, adjval) != 0) panic("semop - can't undo undos"); } for (j = 0; j < nsops; j++) semaptr->_sem_base[sops[j].sem_num].semval -= sops[j].sem_op; SEM_PRINTF(("eval = %d from semundo_adjust\n", eval)); return(eval); } /* loop through the sops */ } /* if (do_undos) */ /* We're definitely done - set the sempid's */ for (i = 0; i < nsops; i++) { sopptr = &sops[i]; semptr = &semaptr->_sem_base[sopptr->sem_num]; semptr->sempid = p->p_pid; } /* Do a wakeup if any semaphore was up'd. */ if (do_wakeup) { SEM_PRINTF(("semop: doing wakeup\n")); #ifdef SEM_WAKEUP sem_wakeup((caddr_t)semaptr); #else wakeup((caddr_t)semaptr); #endif SEM_PRINTF(("semop: back from wakeup\n")); } SEM_PRINTF(("semop: done\n")); *retval = 0; return(0); } /* * Go through the undo structures for this process and apply the adjustments to * semaphores. */ /*ARGSUSED*/ void semexit(p, v) struct proc *p; void *v; { struct sem_undo *suptr; struct sem_undo **supptr; /* * Go through the chain of undo vectors looking for one associated with * this process. */ for (supptr = &semu_list; (suptr = *supptr) != NULL; supptr = &suptr->un_next) { if (suptr->un_proc == p) break; } /* * If there is no undo vector, skip to the end. */ if (suptr == NULL) return; /* * We now have an undo vector for this process. */ SEM_PRINTF(("proc @%p has undo structure with %d entries\n", p, suptr->un_cnt)); /* * If there are any active undo elements then process them. */ if (suptr->un_cnt > 0) { int ix; for (ix = 0; ix < suptr->un_cnt; ix++) { int semid = suptr->un_ent[ix].un_id; int semnum = suptr->un_ent[ix].un_num; int adjval = suptr->un_ent[ix].un_adjval; struct semid_ds *semaptr; semaptr = &sema[semid]; if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0) panic("semexit - semid not allocated"); if (semnum >= semaptr->sem_nsems) panic("semexit - semnum out of range"); SEM_PRINTF(("semexit: %p id=%d num=%d(adj=%d) ; sem=%d\n", suptr->un_proc, suptr->un_ent[ix].un_id, suptr->un_ent[ix].un_num, suptr->un_ent[ix].un_adjval, semaptr->_sem_base[semnum].semval)); if (adjval < 0 && semaptr->_sem_base[semnum].semval < -adjval) semaptr->_sem_base[semnum].semval = 0; else semaptr->_sem_base[semnum].semval += adjval; #ifdef SEM_WAKEUP sem_wakeup((caddr_t)semaptr); #else wakeup((caddr_t)semaptr); #endif SEM_PRINTF(("semexit: back from wakeup\n")); } } /* * Deallocate the undo vector. */ SEM_PRINTF(("removing vector\n")); suptr->un_proc = NULL; *supptr = suptr->un_next; }