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NetBSD/sys/kern/sysv_sem.c

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/* $NetBSD: sysv_sem.c,v 1.98 2019/08/07 00:38:02 pgoyette Exp $ */
/*-
* Copyright (c) 1999, 2007 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, and by Andrew Doran.
*
* 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.
*
* 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 <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: sysv_sem.c,v 1.98 2019/08/07 00:38:02 pgoyette Exp $");
#ifdef _KERNEL_OPT
#include "opt_sysv.h"
#endif
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/sem.h>
#include <sys/sysctl.h>
#include <sys/kmem.h>
#include <sys/mount.h> /* XXX for <sys/syscallargs.h> */
#include <sys/syscallargs.h>
#include <sys/kauth.h>
#include <sys/once.h>
/*
* Memory areas:
* 1st: Pool of semaphore identifiers
* 2nd: Semaphores
* 3rd: Conditional variables
* 4th: Undo structures
*/
struct semid_ds * sema __read_mostly;
static struct __sem * sem __read_mostly;
static kcondvar_t * semcv __read_mostly;
static int * semu __read_mostly;
static kmutex_t semlock __cacheline_aligned;
static bool sem_realloc_state __read_mostly;
static kcondvar_t sem_realloc_cv;
/*
* List of active undo structures, total number of semaphores,
* and total number of semop waiters.
*/
static struct sem_undo *semu_list __read_mostly;
static u_int semtot __cacheline_aligned;
static u_int sem_waiters __cacheline_aligned;
/* Macro to find a particular sem_undo vector */
#define SEMU(s, ix) ((struct sem_undo *)(((long)s) + ix * seminfo.semusz))
#ifdef SEM_DEBUG
#define SEM_PRINTF(a) printf a
#else
#define SEM_PRINTF(a)
#endif
void *hook; /* cookie from exithook_establish() */
extern int kern_has_sysvsem;
SYSCTL_SETUP_PROTO(sysctl_ipc_sem_setup);
struct sem_undo *semu_alloc(struct proc *);
int semundo_adjust(struct proc *, struct sem_undo **, int, int, int);
void semundo_clear(int, int);
static ONCE_DECL(exithook_control);
static int seminit_exithook(void);
int
seminit(void)
{
int i, sz;
vaddr_t v;
mutex_init(&semlock, MUTEX_DEFAULT, IPL_NONE);
cv_init(&sem_realloc_cv, "semrealc");
sem_realloc_state = false;
semtot = 0;
sem_waiters = 0;
/* Allocate the wired memory for our structures */
sz = ALIGN(seminfo.semmni * sizeof(struct semid_ds)) +
ALIGN(seminfo.semmns * sizeof(struct __sem)) +
ALIGN(seminfo.semmni * sizeof(kcondvar_t)) +
ALIGN(seminfo.semmnu * seminfo.semusz);
sz = round_page(sz);
v = uvm_km_alloc(kernel_map, sz, 0, UVM_KMF_WIRED|UVM_KMF_ZERO);
if (v == 0) {
printf("sysv_sem: cannot allocate memory");
return ENOMEM;
}
sema = (void *)v;
sem = (void *)((uintptr_t)sema +
ALIGN(seminfo.semmni * sizeof(struct semid_ds)));
semcv = (void *)((uintptr_t)sem +
ALIGN(seminfo.semmns * sizeof(struct __sem)));
semu = (void *)((uintptr_t)semcv +
ALIGN(seminfo.semmni * sizeof(kcondvar_t)));
for (i = 0; i < seminfo.semmni; i++) {
sema[i]._sem_base = 0;
sema[i].sem_perm.mode = 0;
cv_init(&semcv[i], "semwait");
}
for (i = 0; i < seminfo.semmnu; i++) {
struct sem_undo *suptr = SEMU(semu, i);
suptr->un_proc = NULL;
}
semu_list = NULL;
kern_has_sysvsem = 1;
return 0;
}
static int
seminit_exithook(void)
{
hook = exithook_establish(semexit, NULL);
return 0;
}
int
semfini(void)
{
int i, sz;
vaddr_t v = (vaddr_t)sema;
/* Don't allow module unload if we're busy */
mutex_enter(&semlock);
if (semtot) {
mutex_exit(&semlock);
return 1;
}
/* Remove the exit hook */
if (hook)
exithook_disestablish(hook);
/* Destroy all our condvars */
for (i = 0; i < seminfo.semmni; i++) {
cv_destroy(&semcv[i]);
}
/* Free the wired memory that we allocated */
sz = ALIGN(seminfo.semmni * sizeof(struct semid_ds)) +
ALIGN(seminfo.semmns * sizeof(struct __sem)) +
ALIGN(seminfo.semmni * sizeof(kcondvar_t)) +
ALIGN(seminfo.semmnu * seminfo.semusz);
sz = round_page(sz);
uvm_km_free(kernel_map, v, sz, UVM_KMF_WIRED);
/* Destroy the last cv and mutex */
cv_destroy(&sem_realloc_cv);
mutex_exit(&semlock);
mutex_destroy(&semlock);
kern_has_sysvsem = 0;
return 0;
}
static int
semrealloc(int newsemmni, int newsemmns, int newsemmnu)
{
struct semid_ds *new_sema, *old_sema;
struct __sem *new_sem;
struct sem_undo *new_semu_list, *suptr, *nsuptr;
int *new_semu;
kcondvar_t *new_semcv;
vaddr_t v;
int i, j, lsemid, nmnus, sz;
if (newsemmni < 1 || newsemmns < 1 || newsemmnu < 1)
return EINVAL;
/* Allocate the wired memory for our structures */
sz = ALIGN(newsemmni * sizeof(struct semid_ds)) +
ALIGN(newsemmns * sizeof(struct __sem)) +
ALIGN(newsemmni * sizeof(kcondvar_t)) +
ALIGN(newsemmnu * seminfo.semusz);
sz = round_page(sz);
v = uvm_km_alloc(kernel_map, sz, 0, UVM_KMF_WIRED|UVM_KMF_ZERO);
if (v == 0)
return ENOMEM;
mutex_enter(&semlock);
if (sem_realloc_state) {
mutex_exit(&semlock);
uvm_km_free(kernel_map, v, sz, UVM_KMF_WIRED);
return EBUSY;
}
sem_realloc_state = true;
if (sem_waiters) {
/*
* Mark reallocation state, wake-up all waiters,
* and wait while they will all exit.
*/
for (i = 0; i < seminfo.semmni; i++)
cv_broadcast(&semcv[i]);
while (sem_waiters)
cv_wait(&sem_realloc_cv, &semlock);
}
old_sema = sema;
/* Get the number of last slot */
lsemid = 0;
for (i = 0; i < seminfo.semmni; i++)
if (sema[i].sem_perm.mode & SEM_ALLOC)
lsemid = i;
/* Get the number of currently used undo structures */
nmnus = 0;
for (i = 0; i < seminfo.semmnu; i++) {
suptr = SEMU(semu, i);
if (suptr->un_proc == NULL)
continue;
nmnus++;
}
/* We cannot reallocate less memory than we use */
if (lsemid >= newsemmni || semtot > newsemmns || nmnus > newsemmnu) {
mutex_exit(&semlock);
uvm_km_free(kernel_map, v, sz, UVM_KMF_WIRED);
return EBUSY;
}
new_sema = (void *)v;
new_sem = (void *)((uintptr_t)new_sema +
ALIGN(newsemmni * sizeof(struct semid_ds)));
new_semcv = (void *)((uintptr_t)new_sem +
ALIGN(newsemmns * sizeof(struct __sem)));
new_semu = (void *)((uintptr_t)new_semcv +
ALIGN(newsemmni * sizeof(kcondvar_t)));
/* Initialize all semaphore identifiers and condvars */
for (i = 0; i < newsemmni; i++) {
new_sema[i]._sem_base = 0;
new_sema[i].sem_perm.mode = 0;
cv_init(&new_semcv[i], "semwait");
}
for (i = 0; i < newsemmnu; i++) {
nsuptr = SEMU(new_semu, i);
nsuptr->un_proc = NULL;
}
/*
* Copy all identifiers, semaphores and list of the
* undo structures to the new memory allocation.
*/
j = 0;
for (i = 0; i <= lsemid; i++) {
if ((sema[i].sem_perm.mode & SEM_ALLOC) == 0)
continue;
memcpy(&new_sema[i], &sema[i], sizeof(struct semid_ds));
new_sema[i]._sem_base = &new_sem[j];
memcpy(new_sema[i]._sem_base, sema[i]._sem_base,
(sizeof(struct __sem) * sema[i].sem_nsems));
j += sema[i].sem_nsems;
}
KASSERT(j == semtot);
j = 0;
new_semu_list = NULL;
for (suptr = semu_list; suptr != NULL; suptr = suptr->un_next) {
KASSERT(j < newsemmnu);
nsuptr = SEMU(new_semu, j);
memcpy(nsuptr, suptr, SEMUSZ);
nsuptr->un_next = new_semu_list;
new_semu_list = nsuptr;
j++;
}
for (i = 0; i < seminfo.semmni; i++) {
KASSERT(cv_has_waiters(&semcv[i]) == false);
cv_destroy(&semcv[i]);
}
sz = ALIGN(seminfo.semmni * sizeof(struct semid_ds)) +
ALIGN(seminfo.semmns * sizeof(struct __sem)) +
ALIGN(seminfo.semmni * sizeof(kcondvar_t)) +
ALIGN(seminfo.semmnu * seminfo.semusz);
sz = round_page(sz);
/* Set the pointers and update the new values */
sema = new_sema;
sem = new_sem;
semcv = new_semcv;
semu = new_semu;
semu_list = new_semu_list;
seminfo.semmni = newsemmni;
seminfo.semmns = newsemmns;
seminfo.semmnu = newsemmnu;
/* Reallocation completed - notify all waiters, if any */
sem_realloc_state = false;
cv_broadcast(&sem_realloc_cv);
mutex_exit(&semlock);
uvm_km_free(kernel_map, (vaddr_t)old_sema, sz, UVM_KMF_WIRED);
return 0;
}
/*
* Placebo.
*/
int
sys_semconfig(struct lwp *l, const struct sys_semconfig_args *uap, register_t *retval)
{
RUN_ONCE(&exithook_control, seminit_exithook);
*retval = 0;
return 0;
}
/*
* Allocate a new sem_undo structure for a process.
* => Returns NULL on failure.
*/
struct sem_undo *
semu_alloc(struct proc *p)
{
struct sem_undo *suptr, **supptr;
bool attempted = false;
int i;
KASSERT(mutex_owned(&semlock));
again:
/* Look for a free structure. */
for (i = 0; i < seminfo.semmnu; i++) {
suptr = SEMU(semu, i);
if (suptr->un_proc == NULL) {
/* Found. Fill it in and return. */
suptr->un_next = semu_list;
semu_list = suptr;
suptr->un_cnt = 0;
suptr->un_proc = p;
return suptr;
}
}
/* Not found. Attempt to free some structures. */
if (!attempted) {
bool freed = false;
attempted = true;
supptr = &semu_list;
while ((suptr = *supptr) != NULL) {
if (suptr->un_cnt == 0) {
suptr->un_proc = NULL;
*supptr = suptr->un_next;
freed = true;
} else {
supptr = &suptr->un_next;
}
}
if (freed) {
goto again;
}
}
return NULL;
}
/*
* Adjust a particular entry for a particular proc
*/
int
semundo_adjust(struct proc *p, struct sem_undo **supptr, int semid, int semnum,
int adjval)
{
struct sem_undo *suptr;
struct sem_undo_entry *sunptr;
int i;
KASSERT(mutex_owned(&semlock));
/*
* 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)
break;
if (suptr == NULL) {
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;
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 (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(int semid, int semnum)
{
struct sem_undo *suptr;
struct sem_undo_entry *sunptr, *sunend;
KASSERT(mutex_owned(&semlock));
for (suptr = semu_list; suptr != NULL; suptr = suptr->un_next)
for (sunptr = &suptr->un_ent[0],
sunend = sunptr + suptr->un_cnt; sunptr < sunend;) {
if (sunptr->un_id == semid) {
if (semnum == -1 || sunptr->un_num == semnum) {
suptr->un_cnt--;
sunend--;
if (sunptr != sunend)
*sunptr = *sunend;
if (semnum != -1)
break;
else
continue;
}
}
sunptr++;
}
}
int
sys_____semctl50(struct lwp *l, const struct sys_____semctl50_args *uap,
register_t *retval)
{
/* {
syscallarg(int) semid;
syscallarg(int) semnum;
syscallarg(int) cmd;
syscallarg(union __semun *) arg;
} */
struct semid_ds sembuf;
int cmd, error;
void *pass_arg;
union __semun karg;
RUN_ONCE(&exithook_control, seminit_exithook);
cmd = SCARG(uap, cmd);
pass_arg = get_semctl_arg(cmd, &sembuf, &karg);
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(l, 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(struct lwp *l, int semid, int semnum, int cmd, void *v,
register_t *retval)
{
kauth_cred_t cred = l->l_cred;
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));
mutex_enter(&semlock);
ix = IPCID_TO_IX(semid);
if (ix < 0 || ix >= seminfo.semmni) {
mutex_exit(&semlock);
return (EINVAL);
}
semaptr = &sema[ix];
if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 ||
semaptr->sem_perm._seq != IPCID_TO_SEQ(semid)) {
mutex_exit(&semlock);
return (EINVAL);
}
switch (cmd) {
case IPC_RMID:
if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_M)) != 0)
break;
semaptr->sem_perm.cuid = kauth_cred_geteuid(cred);
semaptr->sem_perm.uid = kauth_cred_geteuid(cred);
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);
cv_broadcast(&semcv[ix]);
break;
case IPC_SET:
if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_M)))
break;
KASSERT(sembuf != NULL);
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_second;
break;
case IPC_STAT:
if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R)))
break;
KASSERT(sembuf != NULL);
memset(sembuf, 0, sizeof *sembuf);
sembuf->sem_perm = semaptr->sem_perm;
sembuf->sem_perm.mode &= 0777;
sembuf->sem_nsems = semaptr->sem_nsems;
sembuf->sem_otime = semaptr->sem_otime;
sembuf->sem_ctime = semaptr->sem_ctime;
break;
case GETNCNT:
if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R)))
break;
if (semnum < 0 || semnum >= semaptr->sem_nsems) {
error = EINVAL;
break;
}
*retval = semaptr->_sem_base[semnum].semncnt;
break;
case GETPID:
if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R)))
break;
if (semnum < 0 || semnum >= semaptr->sem_nsems) {
error = EINVAL;
break;
}
*retval = semaptr->_sem_base[semnum].sempid;
break;
case GETVAL:
if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R)))
break;
if (semnum < 0 || semnum >= semaptr->sem_nsems) {
error = EINVAL;
break;
}
*retval = semaptr->_sem_base[semnum].semval;
break;
case GETALL:
if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R)))
break;
KASSERT(arg != NULL);
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)))
break;
if (semnum < 0 || semnum >= semaptr->sem_nsems) {
error = EINVAL;
break;
}
*retval = semaptr->_sem_base[semnum].semzcnt;
break;
case SETVAL:
if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_W)))
break;
if (semnum < 0 || semnum >= semaptr->sem_nsems) {
error = EINVAL;
break;
}
KASSERT(arg != NULL);
if ((unsigned int)arg->val > seminfo.semvmx) {
error = ERANGE;
break;
}
semaptr->_sem_base[semnum].semval = arg->val;
semundo_clear(ix, semnum);
cv_broadcast(&semcv[ix]);
break;
case SETALL:
if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_W)))
break;
KASSERT(arg != NULL);
for (i = 0; i < semaptr->sem_nsems; i++) {
unsigned short semval;
error = copyin(&arg->array[i], &semval,
sizeof(arg->array[i]));
if (error != 0)
break;
if ((unsigned int)semval > seminfo.semvmx) {
error = ERANGE;
break;
}
semaptr->_sem_base[i].semval = semval;
}
semundo_clear(ix, -1);
cv_broadcast(&semcv[ix]);
break;
default:
error = EINVAL;
break;
}
mutex_exit(&semlock);
return (error);
}
int
sys_semget(struct lwp *l, const struct sys_semget_args *uap, register_t *retval)
{
/* {
syscallarg(key_t) key;
syscallarg(int) nsems;
syscallarg(int) semflg;
} */
int semid, error = 0;
int key = SCARG(uap, key);
int nsems = SCARG(uap, nsems);
int semflg = SCARG(uap, semflg);
kauth_cred_t cred = l->l_cred;
RUN_ONCE(&exithook_control, seminit_exithook);
SEM_PRINTF(("semget(0x%x, %d, 0%o)\n", key, nsems, semflg));
mutex_enter(&semlock);
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 ((error = ipcperm(cred, &sema[semid].sem_perm,
semflg & 0700)))
goto out;
if (nsems > 0 && sema[semid].sem_nsems < nsems) {
SEM_PRINTF(("too small\n"));
error = EINVAL;
goto out;
}
if ((semflg & IPC_CREAT) && (semflg & IPC_EXCL)) {
SEM_PRINTF(("not exclusive\n"));
error = EEXIST;
goto out;
}
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));
error = EINVAL;
goto out;
}
if (nsems > seminfo.semmns - semtot) {
SEM_PRINTF(("not enough semaphores left "
"(need %d, got %d)\n",
nsems, seminfo.semmns - semtot));
error = ENOSPC;
goto out;
}
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"));
error = ENOSPC;
goto out;
}
SEM_PRINTF(("semid %d is available\n", semid));
sema[semid].sem_perm._key = key;
sema[semid].sem_perm.cuid = kauth_cred_geteuid(cred);
sema[semid].sem_perm.uid = kauth_cred_geteuid(cred);
sema[semid].sem_perm.cgid = kauth_cred_getegid(cred);
sema[semid].sem_perm.gid = kauth_cred_getegid(cred);
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_second;
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"));
error = ENOENT;
goto out;
}
found:
*retval = IXSEQ_TO_IPCID(semid, sema[semid].sem_perm);
out:
mutex_exit(&semlock);
return (error);
}
#define SMALL_SOPS 8
int
sys_semop(struct lwp *l, const struct sys_semop_args *uap, register_t *retval)
{
/* {
syscallarg(int) semid;
syscallarg(struct sembuf *) sops;
syscallarg(size_t) nsops;
} */
struct proc *p = l->l_proc;
int semid = SCARG(uap, semid), seq;
size_t nsops = SCARG(uap, nsops);
struct sembuf small_sops[SMALL_SOPS];
struct sembuf *sops;
struct semid_ds *semaptr;
struct sembuf *sopptr = NULL;
struct __sem *semptr = NULL;
struct sem_undo *suptr = NULL;
kauth_cred_t cred = l->l_cred;
int i, error;
int do_wakeup, do_undos;
RUN_ONCE(&exithook_control, seminit_exithook);
SEM_PRINTF(("call to semop(%d, %p, %zd)\n", semid, SCARG(uap,sops), nsops));
if (__predict_false((p->p_flag & PK_SYSVSEM) == 0)) {
mutex_enter(p->p_lock);
p->p_flag |= PK_SYSVSEM;
mutex_exit(p->p_lock);
}
restart:
if (nsops <= SMALL_SOPS) {
sops = small_sops;
} else if (nsops <= seminfo.semopm) {
sops = kmem_alloc(nsops * sizeof(*sops), KM_SLEEP);
} else {
SEM_PRINTF(("too many sops (max=%d, nsops=%zd)\n",
seminfo.semopm, nsops));
return (E2BIG);
}
error = copyin(SCARG(uap, sops), sops, nsops * sizeof(sops[0]));
if (error) {
SEM_PRINTF(("error = %d from copyin(%p, %p, %zd)\n", error,
SCARG(uap, sops), &sops, nsops * sizeof(sops[0])));
if (sops != small_sops)
kmem_free(sops, nsops * sizeof(*sops));
return error;
}
mutex_enter(&semlock);
/* In case of reallocation, we will wait for completion */
while (__predict_false(sem_realloc_state))
cv_wait(&sem_realloc_cv, &semlock);
semid = IPCID_TO_IX(semid); /* Convert back to zero origin */
if (semid < 0 || semid >= seminfo.semmni) {
error = EINVAL;
goto out;
}
semaptr = &sema[semid];
seq = IPCID_TO_SEQ(SCARG(uap, semid));
if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 ||
semaptr->sem_perm._seq != seq) {
error = EINVAL;
goto out;
}
if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_W))) {
SEM_PRINTF(("error = %d from ipaccess\n", error));
goto out;
}
for (i = 0; i < nsops; i++)
if (sops[i].sem_num >= semaptr->sem_nsems) {
error = EFBIG;
goto out;
}
/*
* 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];
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));
while (i-- > 0)
semaptr->_sem_base[sops[i].sem_num].semval -=
sops[i].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) {
error = EAGAIN;
goto out;
}
if (sopptr->sem_op == 0)
semptr->semzcnt++;
else
semptr->semncnt++;
sem_waiters++;
SEM_PRINTF(("semop: good night!\n"));
error = cv_wait_sig(&semcv[semid], &semlock);
SEM_PRINTF(("semop: good morning (error=%d)!\n", error));
sem_waiters--;
/* Notify reallocator, if it is waiting */
cv_broadcast(&sem_realloc_cv);
/*
* Make sure that the semaphore still exists
*/
if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 ||
semaptr->sem_perm._seq != seq) {
error = EIDRM;
goto out;
}
/*
* The semaphore is still alive. Readjust the count of
* waiting processes.
*/
semptr = &semaptr->_sem_base[sopptr->sem_num];
if (sopptr->sem_op == 0)
semptr->semzcnt--;
else
semptr->semncnt--;
/* In case of such state, restart the call */
if (sem_realloc_state) {
mutex_exit(&semlock);
goto restart;
}
/* Is it really morning, or was our sleep interrupted? */
if (error != 0) {
error = EINTR;
goto out;
}
SEM_PRINTF(("semop: good morning!\n"));
}
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;
error = semundo_adjust(p, &suptr, semid,
sops[i].sem_num, -adjval);
if (error == 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.
*/
while (i-- > 0) {
if ((sops[i].sem_flg & SEM_UNDO) == 0)
continue;
adjval = sops[i].sem_op;
if (adjval == 0)
continue;
if (semundo_adjust(p, &suptr, semid,
sops[i].sem_num, adjval) != 0)
panic("semop - can't undo undos");
}
for (i = 0; i < nsops; i++)
semaptr->_sem_base[sops[i].sem_num].semval -=
sops[i].sem_op;
SEM_PRINTF(("error = %d from semundo_adjust\n", error));
goto out;
} /* 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;
}
/* Update sem_otime */
semaptr->sem_otime = time_second;
/* Do a wakeup if any semaphore was up'd. */
if (do_wakeup) {
SEM_PRINTF(("semop: doing wakeup\n"));
cv_broadcast(&semcv[semid]);
SEM_PRINTF(("semop: back from wakeup\n"));
}
SEM_PRINTF(("semop: done\n"));
*retval = 0;
out:
mutex_exit(&semlock);
if (sops != small_sops)
kmem_free(sops, nsops * sizeof(*sops));
return error;
}
/*
* Go through the undo structures for this process and apply the
* adjustments to semaphores.
*/
/*ARGSUSED*/
void
semexit(struct proc *p, void *v)
{
struct sem_undo *suptr;
struct sem_undo **supptr;
if ((p->p_flag & PK_SYSVSEM) == 0)
return;
mutex_enter(&semlock);
/*
* 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) {
mutex_exit(&semlock);
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)
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;
cv_broadcast(&semcv[semid]);
SEM_PRINTF(("semexit: back from wakeup\n"));
}
}
/*
* Deallocate the undo vector.
*/
SEM_PRINTF(("removing vector\n"));
suptr->un_proc = NULL;
*supptr = suptr->un_next;
mutex_exit(&semlock);
}
/*
* Sysctl initialization and nodes.
*/
static int
sysctl_ipc_semmni(SYSCTLFN_ARGS)
{
int newsize, error;
struct sysctlnode node;
node = *rnode;
node.sysctl_data = &newsize;
newsize = seminfo.semmni;
error = sysctl_lookup(SYSCTLFN_CALL(&node));
if (error || newp == NULL)
return error;
return semrealloc(newsize, seminfo.semmns, seminfo.semmnu);
}
static int
sysctl_ipc_semmns(SYSCTLFN_ARGS)
{
int newsize, error;
struct sysctlnode node;
node = *rnode;
node.sysctl_data = &newsize;
newsize = seminfo.semmns;
error = sysctl_lookup(SYSCTLFN_CALL(&node));
if (error || newp == NULL)
return error;
return semrealloc(seminfo.semmni, newsize, seminfo.semmnu);
}
static int
sysctl_ipc_semmnu(SYSCTLFN_ARGS)
{
int newsize, error;
struct sysctlnode node;
node = *rnode;
node.sysctl_data = &newsize;
newsize = seminfo.semmnu;
error = sysctl_lookup(SYSCTLFN_CALL(&node));
if (error || newp == NULL)
return error;
return semrealloc(seminfo.semmni, seminfo.semmns, newsize);
}
SYSCTL_SETUP(sysctl_ipc_sem_setup, "sysctl kern.ipc subtree setup")
{
const struct sysctlnode *node = NULL;
sysctl_createv(clog, 0, NULL, &node,
CTLFLAG_PERMANENT,
CTLTYPE_NODE, "ipc",
SYSCTL_DESCR("SysV IPC options"),
NULL, 0, NULL, 0,
CTL_KERN, KERN_SYSVIPC, CTL_EOL);
if (node == NULL)
return;
sysctl_createv(clog, 0, &node, NULL,
CTLFLAG_PERMANENT | CTLFLAG_READWRITE,
CTLTYPE_INT, "semmni",
SYSCTL_DESCR("Max number of number of semaphore identifiers"),
sysctl_ipc_semmni, 0, &seminfo.semmni, 0,
CTL_CREATE, CTL_EOL);
sysctl_createv(clog, 0, &node, NULL,
CTLFLAG_PERMANENT | CTLFLAG_READWRITE,
CTLTYPE_INT, "semmns",
SYSCTL_DESCR("Max number of number of semaphores in system"),
sysctl_ipc_semmns, 0, &seminfo.semmns, 0,
CTL_CREATE, CTL_EOL);
sysctl_createv(clog, 0, &node, NULL,
CTLFLAG_PERMANENT | CTLFLAG_READWRITE,
CTLTYPE_INT, "semmnu",
SYSCTL_DESCR("Max number of undo structures in system"),
sysctl_ipc_semmnu, 0, &seminfo.semmnu, 0,
CTL_CREATE, CTL_EOL);
}
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