sysv_shm.c revision 61081 
1/* $FreeBSD: head/sys/kern/sysv_shm.c 61081 2000-05-29 22:40:54Z dillon $ */
2/*	$NetBSD: sysv_shm.c,v 1.23 1994/07/04 23:25:12 glass Exp $	*/
3
4/*
5 * Copyright (c) 1994 Adam Glass and Charles Hannum.  All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 3. All advertising materials mentioning features or use of this software
16 *    must display the following acknowledgement:
17 *	This product includes software developed by Adam Glass and Charles
18 *	Hannum.
19 * 4. The names of the authors may not be used to endorse or promote products
20 *    derived from this software without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
23 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
24 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
25 * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT,
26 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
27 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
28 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
29 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
30 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
31 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32 */
33
34#include "opt_compat.h"
35#include "opt_rlimit.h"
36#include "opt_sysvipc.h"
37
38#include <sys/param.h>
39#include <sys/systm.h>
40#include <sys/sysproto.h>
41#include <sys/kernel.h>
42#include <sys/sysctl.h>
43#include <sys/shm.h>
44#include <sys/proc.h>
45#include <sys/malloc.h>
46#include <sys/mman.h>
47#include <sys/stat.h>
48#include <sys/sysent.h>
49
50#include <vm/vm.h>
51#include <vm/vm_param.h>
52#include <sys/lock.h>
53#include <vm/pmap.h>
54#include <vm/vm_object.h>
55#include <vm/vm_map.h>
56#include <vm/vm_page.h>
57#include <vm/vm_pager.h>
58
59static MALLOC_DEFINE(M_SHM, "shm", "SVID compatible shared memory segments");
60
61struct oshmctl_args;
62static int oshmctl __P((struct proc *p, struct oshmctl_args *uap));
63
64static int shmget_allocate_segment __P((struct proc *p, struct shmget_args *uap, int mode));
65static int shmget_existing __P((struct proc *p, struct shmget_args *uap, int mode, int segnum));
66
67/* XXX casting to (sy_call_t *) is bogus, as usual. */
68static sy_call_t *shmcalls[] = {
69	(sy_call_t *)shmat, (sy_call_t *)oshmctl,
70	(sy_call_t *)shmdt, (sy_call_t *)shmget,
71	(sy_call_t *)shmctl
72};
73
74#define	SHMSEG_FREE     	0x0200
75#define	SHMSEG_REMOVED  	0x0400
76#define	SHMSEG_ALLOCATED	0x0800
77#define	SHMSEG_WANTED		0x1000
78
79static int shm_last_free, shm_nused, shm_committed, shmalloced;
80static struct shmid_ds	*shmsegs;
81
82struct shm_handle {
83	/* vm_offset_t kva; */
84	vm_object_t shm_object;
85};
86
87struct shmmap_state {
88	vm_offset_t va;
89	int shmid;
90};
91
92static void shm_deallocate_segment __P((struct shmid_ds *));
93static int shm_find_segment_by_key __P((key_t));
94static struct shmid_ds *shm_find_segment_by_shmid __P((int));
95static int shm_delete_mapping __P((struct proc *, struct shmmap_state *));
96static void shmrealloc __P((void));
97static void shminit __P((void *));
98
99/*
100 * Tuneable values
101 */
102#ifndef SHMMAXPGS
103#define	SHMMAXPGS	1024	/* XXX increase this, it's not in kva! */
104#endif
105#ifndef SHMMAX
106#define	SHMMAX	(SHMMAXPGS*PAGE_SIZE)
107#endif
108#ifndef SHMMIN
109#define	SHMMIN	1
110#endif
111#ifndef SHMMNI
112#define	SHMMNI	96
113#endif
114#ifndef SHMSEG
115#define	SHMSEG	64
116#endif
117#ifndef SHMALL
118#define	SHMALL	(SHMMAXPGS)
119#endif
120
121struct	shminfo shminfo = {
122	SHMMAX,
123	SHMMIN,
124	SHMMNI,
125	SHMSEG,
126	SHMALL
127};
128
129static int shm_use_phys;
130
131SYSCTL_DECL(_kern_ipc);
132SYSCTL_INT(_kern_ipc, OID_AUTO, shmmax, CTLFLAG_RW, &shminfo.shmmax, 0, "");
133SYSCTL_INT(_kern_ipc, OID_AUTO, shmmin, CTLFLAG_RW, &shminfo.shmmin, 0, "");
134SYSCTL_INT(_kern_ipc, OID_AUTO, shmmni, CTLFLAG_RD, &shminfo.shmmni, 0, "");
135SYSCTL_INT(_kern_ipc, OID_AUTO, shmseg, CTLFLAG_RW, &shminfo.shmseg, 0, "");
136SYSCTL_INT(_kern_ipc, OID_AUTO, shmall, CTLFLAG_RW, &shminfo.shmall, 0, "");
137SYSCTL_INT(_kern_ipc, OID_AUTO, shm_use_phys, CTLFLAG_RW, &shm_use_phys, 0, "");
138
139static int
140shm_find_segment_by_key(key)
141	key_t key;
142{
143	int i;
144
145	for (i = 0; i < shmalloced; i++)
146		if ((shmsegs[i].shm_perm.mode & SHMSEG_ALLOCATED) &&
147		    shmsegs[i].shm_perm.key == key)
148			return i;
149	return -1;
150}
151
152static struct shmid_ds *
153shm_find_segment_by_shmid(shmid)
154	int shmid;
155{
156	int segnum;
157	struct shmid_ds *shmseg;
158
159	segnum = IPCID_TO_IX(shmid);
160	if (segnum < 0 || segnum >= shmalloced)
161		return NULL;
162	shmseg = &shmsegs[segnum];
163	if ((shmseg->shm_perm.mode & (SHMSEG_ALLOCATED | SHMSEG_REMOVED))
164	    != SHMSEG_ALLOCATED ||
165	    shmseg->shm_perm.seq != IPCID_TO_SEQ(shmid))
166		return NULL;
167	return shmseg;
168}
169
170static void
171shm_deallocate_segment(shmseg)
172	struct shmid_ds *shmseg;
173{
174	struct shm_handle *shm_handle;
175	size_t size;
176
177	shm_handle = shmseg->shm_internal;
178	vm_object_deallocate(shm_handle->shm_object);
179	free((caddr_t)shm_handle, M_SHM);
180	shmseg->shm_internal = NULL;
181	size = round_page(shmseg->shm_segsz);
182	shm_committed -= btoc(size);
183	shm_nused--;
184	shmseg->shm_perm.mode = SHMSEG_FREE;
185}
186
187static int
188shm_delete_mapping(p, shmmap_s)
189	struct proc *p;
190	struct shmmap_state *shmmap_s;
191{
192	struct shmid_ds *shmseg;
193	int segnum, result;
194	size_t size;
195
196	segnum = IPCID_TO_IX(shmmap_s->shmid);
197	shmseg = &shmsegs[segnum];
198	size = round_page(shmseg->shm_segsz);
199	result = vm_map_remove(&p->p_vmspace->vm_map, shmmap_s->va, shmmap_s->va + size);
200	if (result != KERN_SUCCESS)
201		return EINVAL;
202	shmmap_s->shmid = -1;
203	shmseg->shm_dtime = time_second;
204	if ((--shmseg->shm_nattch <= 0) &&
205	    (shmseg->shm_perm.mode & SHMSEG_REMOVED)) {
206		shm_deallocate_segment(shmseg);
207		shm_last_free = segnum;
208	}
209	return 0;
210}
211
212#ifndef _SYS_SYSPROTO_H_
213struct shmdt_args {
214	void *shmaddr;
215};
216#endif
217
218int
219shmdt(p, uap)
220	struct proc *p;
221	struct shmdt_args *uap;
222{
223	struct shmmap_state *shmmap_s;
224	int i;
225
226	shmmap_s = (struct shmmap_state *)p->p_vmspace->vm_shm;
227 	if (shmmap_s == NULL)
228 	    return EINVAL;
229	for (i = 0; i < shminfo.shmseg; i++, shmmap_s++)
230		if (shmmap_s->shmid != -1 &&
231		    shmmap_s->va == (vm_offset_t)uap->shmaddr)
232			break;
233	if (i == shminfo.shmseg)
234		return EINVAL;
235	return shm_delete_mapping(p, shmmap_s);
236}
237
238#ifndef _SYS_SYSPROTO_H_
239struct shmat_args {
240	int shmid;
241	void *shmaddr;
242	int shmflg;
243};
244#endif
245
246int
247shmat(p, uap)
248	struct proc *p;
249	struct shmat_args *uap;
250{
251	int error, i, flags;
252	struct shmid_ds *shmseg;
253	struct shmmap_state *shmmap_s = NULL;
254	struct shm_handle *shm_handle;
255	vm_offset_t attach_va;
256	vm_prot_t prot;
257	vm_size_t size;
258	int rv;
259
260	shmmap_s = (struct shmmap_state *)p->p_vmspace->vm_shm;
261	if (shmmap_s == NULL) {
262		size = shminfo.shmseg * sizeof(struct shmmap_state);
263		shmmap_s = malloc(size, M_SHM, M_WAITOK);
264		for (i = 0; i < shminfo.shmseg; i++)
265			shmmap_s[i].shmid = -1;
266		p->p_vmspace->vm_shm = (caddr_t)shmmap_s;
267	}
268	shmseg = shm_find_segment_by_shmid(uap->shmid);
269	if (shmseg == NULL)
270		return EINVAL;
271	error = ipcperm(p, &shmseg->shm_perm,
272	    (uap->shmflg & SHM_RDONLY) ? IPC_R : IPC_R|IPC_W);
273	if (error)
274		return error;
275	for (i = 0; i < shminfo.shmseg; i++) {
276		if (shmmap_s->shmid == -1)
277			break;
278		shmmap_s++;
279	}
280	if (i >= shminfo.shmseg)
281		return EMFILE;
282	size = round_page(shmseg->shm_segsz);
283#ifdef VM_PROT_READ_IS_EXEC
284	prot = VM_PROT_READ | VM_PROT_EXECUTE;
285#else
286	prot = VM_PROT_READ;
287#endif
288	if ((uap->shmflg & SHM_RDONLY) == 0)
289		prot |= VM_PROT_WRITE;
290	flags = MAP_ANON | MAP_SHARED;
291	if (uap->shmaddr) {
292		flags |= MAP_FIXED;
293		if (uap->shmflg & SHM_RND)
294			attach_va = (vm_offset_t)uap->shmaddr & ~(SHMLBA-1);
295		else if (((vm_offset_t)uap->shmaddr & (SHMLBA-1)) == 0)
296			attach_va = (vm_offset_t)uap->shmaddr;
297		else
298			return EINVAL;
299	} else {
300		/* This is just a hint to vm_map_find() about where to put it. */
301		attach_va = round_page((vm_offset_t)p->p_vmspace->vm_taddr + MAXTSIZ + MAXDSIZ);
302	}
303
304	shm_handle = shmseg->shm_internal;
305	vm_object_reference(shm_handle->shm_object);
306	rv = vm_map_find(&p->p_vmspace->vm_map, shm_handle->shm_object,
307		0, &attach_va, size, (flags & MAP_FIXED)?0:1, prot, prot, 0);
308	if (rv != KERN_SUCCESS) {
309		return ENOMEM;
310	}
311	vm_map_inherit(&p->p_vmspace->vm_map,
312		attach_va, attach_va + size, VM_INHERIT_SHARE);
313
314	shmmap_s->va = attach_va;
315	shmmap_s->shmid = uap->shmid;
316	shmseg->shm_lpid = p->p_pid;
317	shmseg->shm_atime = time_second;
318	shmseg->shm_nattch++;
319	p->p_retval[0] = attach_va;
320	return 0;
321}
322
323struct oshmid_ds {
324	struct	ipc_perm shm_perm;	/* operation perms */
325	int	shm_segsz;		/* size of segment (bytes) */
326	ushort	shm_cpid;		/* pid, creator */
327	ushort	shm_lpid;		/* pid, last operation */
328	short	shm_nattch;		/* no. of current attaches */
329	time_t	shm_atime;		/* last attach time */
330	time_t	shm_dtime;		/* last detach time */
331	time_t	shm_ctime;		/* last change time */
332	void	*shm_handle;		/* internal handle for shm segment */
333};
334
335struct oshmctl_args {
336	int shmid;
337	int cmd;
338	struct oshmid_ds *ubuf;
339};
340
341static int
342oshmctl(p, uap)
343	struct proc *p;
344	struct oshmctl_args *uap;
345{
346#ifdef COMPAT_43
347	int error;
348	struct shmid_ds *shmseg;
349	struct oshmid_ds outbuf;
350
351	shmseg = shm_find_segment_by_shmid(uap->shmid);
352	if (shmseg == NULL)
353		return EINVAL;
354	switch (uap->cmd) {
355	case IPC_STAT:
356		error = ipcperm(p, &shmseg->shm_perm, IPC_R);
357		if (error)
358			return error;
359		outbuf.shm_perm = shmseg->shm_perm;
360		outbuf.shm_segsz = shmseg->shm_segsz;
361		outbuf.shm_cpid = shmseg->shm_cpid;
362		outbuf.shm_lpid = shmseg->shm_lpid;
363		outbuf.shm_nattch = shmseg->shm_nattch;
364		outbuf.shm_atime = shmseg->shm_atime;
365		outbuf.shm_dtime = shmseg->shm_dtime;
366		outbuf.shm_ctime = shmseg->shm_ctime;
367		outbuf.shm_handle = shmseg->shm_internal;
368		error = copyout((caddr_t)&outbuf, uap->ubuf, sizeof(outbuf));
369		if (error)
370			return error;
371		break;
372	default:
373		/* XXX casting to (sy_call_t *) is bogus, as usual. */
374		return ((sy_call_t *)shmctl)(p, uap);
375	}
376	return 0;
377#else
378	return EINVAL;
379#endif
380}
381
382#ifndef _SYS_SYSPROTO_H_
383struct shmctl_args {
384	int shmid;
385	int cmd;
386	struct shmid_ds *buf;
387};
388#endif
389
390int
391shmctl(p, uap)
392	struct proc *p;
393	struct shmctl_args *uap;
394{
395	int error;
396	struct shmid_ds inbuf;
397	struct shmid_ds *shmseg;
398
399	shmseg = shm_find_segment_by_shmid(uap->shmid);
400	if (shmseg == NULL)
401		return EINVAL;
402	switch (uap->cmd) {
403	case IPC_STAT:
404		error = ipcperm(p, &shmseg->shm_perm, IPC_R);
405		if (error)
406			return error;
407		error = copyout((caddr_t)shmseg, uap->buf, sizeof(inbuf));
408		if (error)
409			return error;
410		break;
411	case IPC_SET:
412		error = ipcperm(p, &shmseg->shm_perm, IPC_M);
413		if (error)
414			return error;
415		error = copyin(uap->buf, (caddr_t)&inbuf, sizeof(inbuf));
416		if (error)
417			return error;
418		shmseg->shm_perm.uid = inbuf.shm_perm.uid;
419		shmseg->shm_perm.gid = inbuf.shm_perm.gid;
420		shmseg->shm_perm.mode =
421		    (shmseg->shm_perm.mode & ~ACCESSPERMS) |
422		    (inbuf.shm_perm.mode & ACCESSPERMS);
423		shmseg->shm_ctime = time_second;
424		break;
425	case IPC_RMID:
426		error = ipcperm(p, &shmseg->shm_perm, IPC_M);
427		if (error)
428			return error;
429		shmseg->shm_perm.key = IPC_PRIVATE;
430		shmseg->shm_perm.mode |= SHMSEG_REMOVED;
431		if (shmseg->shm_nattch <= 0) {
432			shm_deallocate_segment(shmseg);
433			shm_last_free = IPCID_TO_IX(uap->shmid);
434		}
435		break;
436#if 0
437	case SHM_LOCK:
438	case SHM_UNLOCK:
439#endif
440	default:
441		return EINVAL;
442	}
443	return 0;
444}
445
446#ifndef _SYS_SYSPROTO_H_
447struct shmget_args {
448	key_t key;
449	size_t size;
450	int shmflg;
451};
452#endif
453
454static int
455shmget_existing(p, uap, mode, segnum)
456	struct proc *p;
457	struct shmget_args *uap;
458	int mode;
459	int segnum;
460{
461	struct shmid_ds *shmseg;
462	int error;
463
464	shmseg = &shmsegs[segnum];
465	if (shmseg->shm_perm.mode & SHMSEG_REMOVED) {
466		/*
467		 * This segment is in the process of being allocated.  Wait
468		 * until it's done, and look the key up again (in case the
469		 * allocation failed or it was freed).
470		 */
471		shmseg->shm_perm.mode |= SHMSEG_WANTED;
472		error = tsleep((caddr_t)shmseg, PLOCK | PCATCH, "shmget", 0);
473		if (error)
474			return error;
475		return EAGAIN;
476	}
477	if ((uap->shmflg & (IPC_CREAT | IPC_EXCL)) == (IPC_CREAT | IPC_EXCL))
478		return EEXIST;
479	error = ipcperm(p, &shmseg->shm_perm, mode);
480	if (error)
481		return error;
482	if (uap->size && uap->size > shmseg->shm_segsz)
483		return EINVAL;
484	p->p_retval[0] = IXSEQ_TO_IPCID(segnum, shmseg->shm_perm);
485	return 0;
486}
487
488static int
489shmget_allocate_segment(p, uap, mode)
490	struct proc *p;
491	struct shmget_args *uap;
492	int mode;
493{
494	int i, segnum, shmid, size;
495	struct ucred *cred = p->p_ucred;
496	struct shmid_ds *shmseg;
497	struct shm_handle *shm_handle;
498
499	if (uap->size < shminfo.shmmin || uap->size > shminfo.shmmax)
500		return EINVAL;
501	if (shm_nused >= shminfo.shmmni) /* any shmids left? */
502		return ENOSPC;
503	size = round_page(uap->size);
504	if (shm_committed + btoc(size) > shminfo.shmall)
505		return ENOMEM;
506	if (shm_last_free < 0) {
507		shmrealloc();	/* maybe expand the shmsegs[] array */
508		for (i = 0; i < shmalloced; i++)
509			if (shmsegs[i].shm_perm.mode & SHMSEG_FREE)
510				break;
511		if (i == shmalloced)
512			return ENOSPC;
513		segnum = i;
514	} else  {
515		segnum = shm_last_free;
516		shm_last_free = -1;
517	}
518	shmseg = &shmsegs[segnum];
519	/*
520	 * In case we sleep in malloc(), mark the segment present but deleted
521	 * so that noone else tries to create the same key.
522	 */
523	shmseg->shm_perm.mode = SHMSEG_ALLOCATED | SHMSEG_REMOVED;
524	shmseg->shm_perm.key = uap->key;
525	shmseg->shm_perm.seq = (shmseg->shm_perm.seq + 1) & 0x7fff;
526	shm_handle = (struct shm_handle *)
527	    malloc(sizeof(struct shm_handle), M_SHM, M_WAITOK);
528	shmid = IXSEQ_TO_IPCID(segnum, shmseg->shm_perm);
529
530	/*
531	 * We make sure that we have allocated a pager before we need
532	 * to.
533	 */
534	if (shm_use_phys) {
535		shm_handle->shm_object =
536		    vm_pager_allocate(OBJT_PHYS, 0, size, VM_PROT_DEFAULT, 0);
537	} else {
538		shm_handle->shm_object =
539		    vm_pager_allocate(OBJT_SWAP, 0, size, VM_PROT_DEFAULT, 0);
540	}
541	vm_object_clear_flag(shm_handle->shm_object, OBJ_ONEMAPPING);
542	vm_object_set_flag(shm_handle->shm_object, OBJ_NOSPLIT);
543
544	shmseg->shm_internal = shm_handle;
545	shmseg->shm_perm.cuid = shmseg->shm_perm.uid = cred->cr_uid;
546	shmseg->shm_perm.cgid = shmseg->shm_perm.gid = cred->cr_gid;
547	shmseg->shm_perm.mode = (shmseg->shm_perm.mode & SHMSEG_WANTED) |
548	    (mode & ACCESSPERMS) | SHMSEG_ALLOCATED;
549	shmseg->shm_segsz = uap->size;
550	shmseg->shm_cpid = p->p_pid;
551	shmseg->shm_lpid = shmseg->shm_nattch = 0;
552	shmseg->shm_atime = shmseg->shm_dtime = 0;
553	shmseg->shm_ctime = time_second;
554	shm_committed += btoc(size);
555	shm_nused++;
556	if (shmseg->shm_perm.mode & SHMSEG_WANTED) {
557		/*
558		 * Somebody else wanted this key while we were asleep.  Wake
559		 * them up now.
560		 */
561		shmseg->shm_perm.mode &= ~SHMSEG_WANTED;
562		wakeup((caddr_t)shmseg);
563	}
564	p->p_retval[0] = shmid;
565	return 0;
566}
567
568int
569shmget(p, uap)
570	struct proc *p;
571	struct shmget_args *uap;
572{
573	int segnum, mode, error;
574
575	mode = uap->shmflg & ACCESSPERMS;
576	if (uap->key != IPC_PRIVATE) {
577	again:
578		segnum = shm_find_segment_by_key(uap->key);
579		if (segnum >= 0) {
580			error = shmget_existing(p, uap, mode, segnum);
581			if (error == EAGAIN)
582				goto again;
583			return error;
584		}
585		if ((uap->shmflg & IPC_CREAT) == 0)
586			return ENOENT;
587	}
588	return shmget_allocate_segment(p, uap, mode);
589}
590
591int
592shmsys(p, uap)
593	struct proc *p;
594	/* XXX actually varargs. */
595	struct shmsys_args /* {
596		u_int	which;
597		int	a2;
598		int	a3;
599		int	a4;
600	} */ *uap;
601{
602
603	if (uap->which >= sizeof(shmcalls)/sizeof(shmcalls[0]))
604		return EINVAL;
605	return ((*shmcalls[uap->which])(p, &uap->a2));
606}
607
608void
609shmfork(p1, p2)
610	struct proc *p1, *p2;
611{
612	struct shmmap_state *shmmap_s;
613	size_t size;
614	int i;
615
616	size = shminfo.shmseg * sizeof(struct shmmap_state);
617	shmmap_s = malloc(size, M_SHM, M_WAITOK);
618	bcopy((caddr_t)p1->p_vmspace->vm_shm, (caddr_t)shmmap_s, size);
619	p2->p_vmspace->vm_shm = (caddr_t)shmmap_s;
620	for (i = 0; i < shminfo.shmseg; i++, shmmap_s++)
621		if (shmmap_s->shmid != -1)
622			shmsegs[IPCID_TO_IX(shmmap_s->shmid)].shm_nattch++;
623}
624
625void
626shmexit(p)
627	struct proc *p;
628{
629	struct shmmap_state *shmmap_s;
630	int i;
631
632	shmmap_s = (struct shmmap_state *)p->p_vmspace->vm_shm;
633	for (i = 0; i < shminfo.shmseg; i++, shmmap_s++)
634		if (shmmap_s->shmid != -1)
635			shm_delete_mapping(p, shmmap_s);
636	free((caddr_t)p->p_vmspace->vm_shm, M_SHM);
637	p->p_vmspace->vm_shm = NULL;
638}
639
640static void
641shmrealloc(void)
642{
643	int i;
644	struct shmid_ds *newsegs;
645
646	if (shmalloced >= shminfo.shmmni)
647		return;
648
649	newsegs = malloc(shminfo.shmmni * sizeof(*newsegs), M_SHM, M_WAITOK);
650	if (newsegs == NULL)
651		return;
652	for (i = 0; i < shmalloced; i++)
653		bcopy(&shmsegs[i], &newsegs[i], sizeof(newsegs[0]));
654	for (; i < shminfo.shmmni; i++) {
655		shmsegs[i].shm_perm.mode = SHMSEG_FREE;
656		shmsegs[i].shm_perm.seq = 0;
657	}
658	free(shmsegs, M_SHM);
659	shmsegs = newsegs;
660	shmalloced = shminfo.shmmni;
661}
662
663static void
664shminit(dummy)
665	void *dummy;
666{
667	int i;
668
669	shmalloced = shminfo.shmmni;
670	shmsegs = malloc(shmalloced * sizeof(shmsegs[0]), M_SHM, M_WAITOK);
671	if (shmsegs == NULL)
672		panic("cannot allocate initial memory for sysvshm");
673	for (i = 0; i < shmalloced; i++) {
674		shmsegs[i].shm_perm.mode = SHMSEG_FREE;
675		shmsegs[i].shm_perm.seq = 0;
676	}
677	shm_last_free = 0;
678	shm_nused = 0;
679	shm_committed = 0;
680}
681SYSINIT(sysv_shm, SI_SUB_SYSV_SHM, SI_ORDER_FIRST, shminit, NULL);
682