WebSVN - shark - Blame - Rev 1621 - /shark/branches/xen/modules/sem/sem.c

Rev	Author	Line No.	Line
961	pj	1	/*
		2	* Project: S.Ha.R.K.
		3	*
		4	* Coordinators:
		5	* Giorgio Buttazzo <giorgio@sssup.it>
		6	* Paolo Gai <pj@gandalf.sssup.it>
		7	*
		8	* Authors :
		9	* Paolo Gai <pj@gandalf.sssup.it>
		10	* Massimiliano Giorgi <massy@gandalf.sssup.it>
		11	* Luca Abeni <luca@gandalf.sssup.it>
		12	* (see the web pages for full authors list)
		13	*
		14	* ReTiS Lab (Scuola Superiore S.Anna - Pisa - Italy)
		15	*
		16	* http://www.sssup.it
		17	* http://retis.sssup.it
		18	* http://shark.sssup.it
		19	*/
		20
		21	/**
		22	------------
1043	tullio	23	CVS : $Id: sem.c,v 1.3 2006-06-12 12:29:34 tullio Exp $
961	pj	24
		25	File: $File$
1043	tullio	26	Revision: $Revision: 1.3 $
		27	Last update: $Date: 2006-06-12 12:29:34 $
961	pj	28	------------
		29
		30	This file contains the Hartik 3.3.1 Semaphore functions
		31
		32	Author: Giuseppe Lipari
		33
		34	Semaphores:
		35	this is the generalized version of the primitives signal & wait
		36	In this case, the user can specify the number to inc/dec the
		37	semaphore's counter. It is useful in the buffer management
		38	(see port section)
		39
		40	**/
		41
		42	/*
		43	* Copyright (C) 2000 Paolo Gai
		44	*
		45	* This program is free software; you can redistribute it and/or modify
		46	* it under the terms of the GNU General Public License as published by
		47	* the Free Software Foundation; either version 2 of the License, or
		48	* (at your option) any later version.
		49	*
		50	* This program is distributed in the hope that it will be useful,
		51	* but WITHOUT ANY WARRANTY; without even the implied warranty of
		52	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
		53	* GNU General Public License for more details.
		54	*
		55	* You should have received a copy of the GNU General Public License
		56	* along with this program; if not, write to the Free Software
		57	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
		58	*
		59	*/
		60
		61
		62	#include <stdarg.h>
		63	#include <sem/sem/sem.h>
		64	#include <kernel/config.h>
		65	#include <ll/ll.h>
1621	fabio	66	#include <arch/string.h>
961	pj	67	#include <kernel/const.h>
		68	#include <sys/types.h>
		69	#include <kernel/descr.h>
		70	#include <kernel/var.h>
		71	#include <kernel/func.h>
		72	#include <limits.h>
		73	#include <fcntl.h>
		74
		75	#include <tracer.h>
		76
		77	/* Semaphores descriptor tables */
		78	static struct sem_des {
		79	char name; / a name, for named semaphores */
		80	int index; /* an index for sem_open, containing the sem number */
		81	int count; /* the semaphore counter */
		82	IQUEUE blocked; /* the blocked processes queue */
		83	int next; /* the semaphore queue */
		84	BYTE used; /* 1 if the semaphore is used */
		85	} sem_table[SEM_NSEMS_MAX];
		86
		87
		88	/* this -IS- an extension to the proc_table!!! */
		89	static struct {
		90	int decsem; /* the value required in sem_xwait */
		91	int sem; /* the semaphore on whitch the process is blocked */
		92	} sp_table[MAX_PROC];
		93
		94	static int free_sem; /* Queue of free sem */
		95
		96
		97
		98	/----------------------------------------------------------------------/
		99	/* Cancellation test for semaphores */
		100	/----------------------------------------------------------------------/
		101
		102	/* this is the test that is done when a task is being killed
		103	and it is waiting on a sigwait */
		104	static int semwait_cancellation_point(PID i, void *arg)
		105	{
		106	LEVEL l;
		107
		108	if (proc_table[i].status == WAIT_SEM) {
		109	/* the task that have to be killed is waiting on a sig_wait.
		110	we reset the data structures set in sig_wait and then when the
		111	task will return on the sig_wait it will fall into a
		112	task_testcancel */
		113
		114	/* extract the process from the semaphore queue... */
		115	iq_extract(i,&sem_table[ sp_table[i].sem ].blocked);
		116
		117	l = proc_table[i].task_level;
		118	level_table[l]->public_unblock(l,i);
		119
		120	return 1;
		121	}
		122
		123	return 0;
		124	}
		125
		126	/----------------------------------------------------------------------/
		127	/* Init the semaphoric structures */
		128	/----------------------------------------------------------------------/
		129	void SEM_register_module(void)
		130	{
		131	int i;
		132
		133	for (i = 0; i < SEM_NSEMS_MAX; i++) {
		134	sem_table[i].name = NULL;
		135	sem_table[i].index = i;
		136	sem_table[i].count = 0;
		137	iq_init(&sem_table[i].blocked, &freedesc, 0);
		138	sem_table[i].next = i+1;
		139	sem_table[i].used = 0;
		140	}
		141	sem_table[SEM_NSEMS_MAX-1].next = NIL;
		142	free_sem = 0;
		143
		144	register_cancellation_point(semwait_cancellation_point, NULL);
		145	}
		146
		147	/----------------------------------------------------------------------/
		148	/* Allocate a semaphoric descriptor and sets the counter to n */
		149	/----------------------------------------------------------------------/
		150
		151	// the pshared parameter is NRQ for PSE52
		152	int sem_init(sem_t *sem, int pshared, unsigned int value)
		153	{
		154	SYS_FLAGS f;
		155
		156	if (value > SEM_VALUE_MAX)
		157	return EINVAL;
		158
		159	f = kern_fsave();
		160	*sem = free_sem;
		161	if (*sem != NIL) {
		162	free_sem = sem_table[*sem].next;
		163	sem_table[*sem].name = NULL;
		164	sem_table[*sem].count = value;
		165	iq_init(&sem_table[*sem].blocked, &freedesc, 0);
		166	sem_table[*sem].used = 1;
		167	}
		168	else {
		169	errno = ENOSPC;
		170	kern_frestore(f);
		171	return -1;
		172	}
		173	kern_frestore(f);
		174	return 0;
		175	}
		176
		177	/----------------------------------------------------------------------/
		178	/* Frees a semaphores descriptor */
		179	/----------------------------------------------------------------------/
		180	int sem_destroy(sem_t *sem)
		181	{
		182	SYS_FLAGS f;
		183
		184	f = kern_fsave();
		185
		186	if (sem < 0 \|\| sem >= SEM_NSEMS_MAX \|\| !sem_table[*sem].used) {
		187	errno = EINVAL;
		188	kern_frestore(f);
		189	return -1;
		190	}
		191
		192	if (sem_table[*sem].blocked.first != NIL) {
		193	errno = EBUSY;
		194	kern_frestore(f);
		195	return -1;
		196	}
		197
		198	sem_table[*sem].used = 0;
		199	sem_table[*sem].next = free_sem;
		200	free_sem = *sem;
		201
		202	kern_frestore(f);
		203	return 0;
		204	}
		205
		206	/----------------------------------------------------------------------/
		207	/* Allocate a named semaphore */
		208	/----------------------------------------------------------------------/
		209
		210	// the pshared parameter is NRQ for PSE52
		211	sem_t sem_open(const char name, int oflag, ...)
		212	{
		213	int i, j;
		214	int found = 0;
		215	mode_t m;
		216	sem_t sem;
		217	SYS_FLAGS f;
		218
		219	f = kern_fsave();
		220
		221	for (i = 0; i < SEM_NSEMS_MAX; i++)
		222	if (sem_table[i].used) {
		223	if (strcmp(name, sem_table[i].name) == 0) {
		224	found = 1;
		225	break;
		226	}
		227	}
		228	if (found) {
		229	if (oflag == (O_CREAT \| O_EXCL)) {
		230	errno = EEXIST;
		231	kern_frestore(f);
		232	return SEM_FAILED;
		233	} else {
		234	kern_frestore(f);
		235	return &sem_table[i].index;
		236	}
		237	} else {
		238	if (!(oflag & O_CREAT)) {
		239	errno = ENOENT;
		240	kern_frestore(f);
		241	return SEM_FAILED;
		242	} else {
		243	va_list l;
		244
		245	va_start(l, oflag);
		246	m = va_arg(l,mode_t);
		247	j = va_arg(l, int);
		248	va_end(l);
		249
		250	if (j > SEM_VALUE_MAX) {
		251	errno = EINVAL;
		252	kern_frestore(f);
		253	return SEM_FAILED;
		254	}
		255
		256	sem = free_sem;
		257	if (sem != -1) {
		258	free_sem = sem_table[sem].next;
		259	sem_table[sem].name = kern_alloc(strlen((char *)name)+1);
		260	strcpy(sem_table[sem].name, (char *)name);
		261	sem_table[sem].count = j;
		262	iq_init(&sem_table[sem].blocked, &freedesc, 0);
		263	sem_table[sem].used = 1;
		264	kern_frestore(f);
		265	return &sem_table[sem].index;
		266	}
		267	else {
		268	errno = ENOSPC;
		269	kern_frestore(f);
		270	return SEM_FAILED;
		271	}
		272	}
		273	}
		274	}
		275
		276	/----------------------------------------------------------------------/
		277	/* Frees a named semaphore */
		278	/----------------------------------------------------------------------/
		279	int sem_close(sem_t *sem)
		280	{
		281	SYS_FLAGS f;
		282
		283	f = kern_fsave();
		284
		285	if (sem < 0 \|\| sem >= SEM_NSEMS_MAX \|\| !sem_table[*sem].used) {
		286	errno = EINVAL;
		287	kern_frestore(f);
		288	return -1;
		289	}
		290
		291	/* why not???
		292	if (sem_table[*sem].q_first != -1) {
		293	errno = EBUSY;
		294	kern_sti();
		295	return -1;
		296	} */
		297
		298	kern_free(sem_table[sem].name,strlen(sem_table[sem].name)+1);
		299	sem_table[*sem].used = 0;
		300	sem_table[*sem].next = free_sem;
		301	free_sem = *sem;
		302
		303	kern_frestore(f);
		304	return 0;
		305	}
		306
		307	/----------------------------------------------------------------------/
		308	/* Unlink a named semaphore */
		309	/----------------------------------------------------------------------/
		310	int sem_unlink(const char *name)
		311	{
		312	int i;
		313	int found = 0;
		314	SYS_FLAGS f;
		315
		316	f = kern_fsave();
		317
		318	for (i = 0; i < SEM_NSEMS_MAX; i++)
		319	if (sem_table[i].used) {
		320	if (strcmp(name, sem_table[i].name) == 0) {
		321	found = 1;
		322	}
		323	}
		324
		325	if (found) {
		326	kern_free(sem_table[i].name,strlen((char *)name)+1);
		327	sem_table[i].used = 0;
		328	sem_table[i].next = free_sem;
		329	free_sem = i;
		330	kern_frestore(f);
		331	return 0;
		332	} else {
		333	errno = ENOENT;
		334	kern_frestore(f);
		335	return SEM_FAILED;
		336	}
		337	}
		338
		339	/----------------------------------------------------------------------/
		340	/* Generic wait. If it is possible, decrements the sem counter of n, */
		341	/* else blocks the task. */
		342	/----------------------------------------------------------------------/
		343	int sem_wait(sem_t *s)
		344	{
		345	struct sem_des s1; / It speeds up access */
		346
		347	if (s < 0 \|\| s >= SEM_NSEMS_MAX \|\| !sem_table[*s].used) {
		348	errno = EINVAL;
		349	return -1;
		350	}
		351
		352	task_testcancel();
		353
		354	proc_table[exec_shadow].context = kern_context_save();
		355
		356	s1 = &sem_table[*s];
		357
		358	if (s1->blocked.first != NIL \|\| s1->count == 0) {
		359	/* We must block exec task */
		360	LEVEL l; /* for readableness only */
		361
		362	/* tracer stuff */
		363	TRACER_LOGEVENT(FTrace_EVT_set_mutex_wait,(unsigned short int)proc_table[exec_shadow].context,(unsigned int)*s);
		364
		365	kern_epilogue_macro();
		366
		367	l = proc_table[exec_shadow].task_level;
		368	level_table[l]->public_block(l,exec_shadow);
		369
		370	/* we insert the task in the semaphore queue */
		371	proc_table[exec_shadow].status = WAIT_SEM;
		372
		373	/* Prepare sem_table des... */
		374	sp_table[exec_shadow].decsem = 1;
		375	sp_table[exec_shadow].sem = *s;
		376
		377	/* ...and put it in sem queue */
		378	iq_insertlast(exec_shadow,&s1->blocked);
		379
		380	/* and finally we reschedule */
		381	exec = exec_shadow = -1;
		382	scheduler();
		383	kern_context_load(proc_table[exec_shadow].context);
		384
		385	/* sem_wait is a cancellation point... */
		386	task_testcancel();
		387	}
		388	else {
		389	s1->count--;
		390	/* tracer stuff */
		391	TRACER_LOGEVENT(FTrace_EVT_set_mutex_wait,(unsigned short int)proc_table[exec_shadow].context,(unsigned int)*s);
		392	kern_context_load(proc_table[exec_shadow].context);
		393	}
		394
		395	return 0;
		396	}
		397
		398	/----------------------------------------------------------------------/
		399	/* Non-blocking wait */
		400	/----------------------------------------------------------------------/
		401	int sem_trywait(sem_t *s)
		402	{
		403	struct sem_des s1; / It speeds up access */
		404	SYS_FLAGS f;
		405
		406	if (s < 0 \|\| s >= SEM_NSEMS_MAX \|\| !sem_table[*s].used) {
		407	errno = EINVAL;
		408	return -1;
		409	}
		410
		411	f = kern_fsave();
		412
		413	s1 = &sem_table[*s];
		414
		415	if (s1->blocked.first != NIL \|\| s1->count == 0) {
		416	errno = EAGAIN;
		417	kern_frestore(f);
		418	return -1;
		419	}
		420	else
		421	s1->count--;
		422
		423	kern_frestore(f);
		424	return 0;
		425	}
		426
		427
		428	/----------------------------------------------------------------------/
		429	/* Generic wait. If it is possible, decrements the sem counter of n, */
		430	/* else blocks the task. */
		431	/----------------------------------------------------------------------/
		432	int sem_xwait(sem_t *s, int n, int wait)
		433	{
		434	struct sem_des s1; / It speeds up access */
		435
		436	if (s < 0 \|\| s >= SEM_NSEMS_MAX \|\| !sem_table[*s].used) {
		437	errno = EINVAL;
		438	return -1;
		439	}
		440
		441	/* We do not need to save context if we are sure we shall not block! */
		442	if (wait == NON_BLOCK)
		443	kern_cli();
		444	else
		445	proc_table[exec_shadow].context = kern_context_save();
		446
		447	s1 = &sem_table[*s];
		448
		449	/* The non blocking wait is really simple! */
		450	/* We do not suspend or schedule anything */
		451	if (wait == NON_BLOCK) {
		452	if (s1->blocked.first != NIL \|\| s1->count < n) {
		453	errno = EAGAIN;
		454	kern_sti();
		455	return -1;
		456	}
		457	else
		458	s1->count -= n;
		459
		460	kern_sti();
		461	return 0;
		462	}
		463	/* The blocking wait is more complex... */
		464	else {
		465	/* the blocking wait is a cancellation point */
		466	task_testcancel();
		467
		468	if (s1->blocked.first != NIL \|\| s1->count < n) {
		469	/* We must block exec task */
		470	LEVEL l; /* for readableness only */
		471
		472	/* tracer */
		473	TRACER_LOGEVENT(FTrace_EVT_set_mutex_wait,(unsigned short int)proc_table[exec_shadow].context,(unsigned int)*s);
		474
		475	kern_epilogue_macro();
		476
		477	l = proc_table[exec_shadow].task_level;
		478	level_table[l]->public_block(l,exec_shadow);
		479
		480	/* we insert the task in the semaphore queue */
		481	proc_table[exec_shadow].status = WAIT_SEM;
		482
		483	/* Prepare sem_table des... */
		484	sp_table[exec_shadow].decsem = n;
		485	sp_table[exec_shadow].sem = *s;
		486
		487	/* ...and put it in sem queue */
		488	iq_insertlast(exec_shadow,&s1->blocked);
		489
		490	/* and finally we reschedule */
		491	exec = exec_shadow = -1;
		492	scheduler();
		493	kern_context_load(proc_table[exec_shadow].context);
		494
		495	/* sem_wait is a cancellation point... */
		496	task_testcancel();
		497	}
		498	else {
		499	s1->count -= n;
		500	/* tracer */
		501	TRACER_LOGEVENT(FTrace_EVT_set_mutex_wait,(unsigned short int)proc_table[exec_shadow].context,(unsigned int)*s);
		502	kern_context_load(proc_table[exec_shadow].context);
		503	}
		504	}
		505
		506	return 0;
		507	}
		508
		509	/----------------------------------------------------------------------/
		510	/* Generic signal. It increments the sem counter of 1, and wakes one */
		511	/* of the tasks that are blocked on the semaphore, if it is possible.The*/
		512	/* semaphoric queue is a FIFO queue, in order to eliminate deadlocks */
		513	/----------------------------------------------------------------------/
		514	int sem_post(sem_t *s)
		515	{
		516	struct sem_des s1; / it speeds up access */
		517	int p; /* idem */
		518	LEVEL l;
		519
		520	if (s < 0 \|\| s >= SEM_NSEMS_MAX \|\| !sem_table[*s].used) {
		521	errno = EINVAL;
		522	return -1;
		523	}
		524
		525	// ugly patch to call a sem_post!!!
		526	if (ll_ActiveInt()) {
		527	SYS_FLAGS f;
		528	f = kern_fsave();
		529	s1 = &sem_table[*s];
		530	s1->count ++; /* inc sem count */
		531
		532	p = s1->blocked.first;
		533	if (p != NIL && sp_table[p].decsem <= s1->count) {
		534	/* Dec sem count */
		535	s1->count -= sp_table[p].decsem;
		536
		537	/* Get task from blocked queue */
		538	iq_extract(p,&s1->blocked);
		539
		540	l = proc_table[p].task_level;
		541	level_table[l]->public_unblock(l,p);
		542	/* only a task can be awaken */
		543	/* Preempt if necessary */
		544	event_need_reschedule();
		545	}
		546
		547	/* tracer */
1041	tullio	548	TRACER_LOGEVENT(FTrace_EVT_set_mutex_post,(unsigned short int)proc_table[exec_shadow].context,(unsigned int)*s);
961	pj	549	kern_frestore(f);
		550	}
		551	else {
		552	proc_table[exec].context = kern_context_save();
		553
		554	s1 = &sem_table[*s];
		555	s1->count ++; /* inc sem count */
		556
		557	p = s1->blocked.first;
		558	if (p != NIL && sp_table[p].decsem <= s1->count) {
		559	/* Dec sem count */
		560	s1->count -= sp_table[p].decsem;
		561
		562	/* Get task from blocked queue */
		563	iq_extract(p,&s1->blocked);
		564
		565	l = proc_table[p].task_level;
		566	level_table[l]->public_unblock(l,p);
		567	/* only a task can be awaken */
		568	/* Preempt if necessary */
		569	scheduler();
		570	}
		571
		572	/* tracer */
1041	tullio	573	TRACER_LOGEVENT(FTrace_EVT_set_mutex_post,(unsigned short int)proc_table[exec_shadow].context,(unsigned int)*s);
961	pj	574
		575	kern_context_load(proc_table[exec_shadow].context);
		576	}
		577
		578	return 0;
		579	}
		580
		581	/----------------------------------------------------------------------/
		582	/* Generic signal. It increments the sem counter of n, and wakes all the*/
		583	/* tasks that are blocked on the semaphore, if it is possible. The */
		584	/* semaphoric queue is a FIFO queue, in order to eliminate deadlocks */
		585	/----------------------------------------------------------------------/
		586	int sem_xpost(sem_t *s, int n)
		587	{
		588	struct sem_des s1; / it speeds up access */
		589	int p; /* idem */
		590	int fl = 0; /* a flag */
		591	LEVEL l;
		592
		593	if (s < 0 \|\| s >= SEM_NSEMS_MAX \|\| !sem_table[*s].used) {
		594	errno = EINVAL;
		595	return -1;
		596	}
		597
		598	// ugly patch to call a sem_post!!!
		599	if (ll_ActiveInt()) {
		600	SYS_FLAGS f;
		601	f = kern_fsave();
		602	s1 = &sem_table[*s];
		603	s1->count += n; /* inc sem count */
		604
		605	p = s1->blocked.first;
		606	while (p != NIL && sp_table[p].decsem <= s1->count) {
		607	/* Dec sem count */
		608	s1->count -= sp_table[p].decsem;
		609
		610	/* Get task from blocked queue */
		611	iq_extract(p,&s1->blocked);
		612
		613	l = proc_table[p].task_level;
		614	level_table[l]->public_unblock(l,p);
		615
		616	/* Next task to wake */
		617	p = s1->blocked.first;
		618
		619	fl = 1;
		620	}
		621
		622	/* tracer */
1043	tullio	623	TRACER_LOGEVENT(FTrace_EVT_set_mutex_post,(unsigned short int)proc_table[exec_shadow].context,(unsigned int)*s);
961	pj	624
		625	/* Preempt if necessary */
		626	if (fl) event_need_reschedule();
		627	kern_frestore(f);
		628	}
		629	else {
		630	proc_table[exec].context = kern_context_save();
		631
		632	s1 = &sem_table[*s];
		633	s1->count += n; /* inc sem count */
		634
		635	p = s1->blocked.first;
		636	while (p != NIL && sp_table[p].decsem <= s1->count) {
		637	/* Dec sem count */
		638	s1->count -= sp_table[p].decsem;
		639
		640	/* Get task from blocked queue */
		641	iq_extract(p,&s1->blocked);
		642
		643	l = proc_table[p].task_level;
		644	level_table[l]->public_unblock(l,p);
		645
		646	/* Next task to wake */
		647	p = s1->blocked.first;
		648
		649	fl = 1;
		650	}
		651
		652	/* tracer */
1043	tullio	653	TRACER_LOGEVENT(FTrace_EVT_set_mutex_post,(unsigned short int)proc_table[exec_shadow].context,(unsigned int)*s);
961	pj	654
		655	/* Preempt if necessary */
		656	if (fl) scheduler();
		657
		658	kern_context_load(proc_table[exec_shadow].context);
		659	}
		660
		661	return 0;
		662	}
		663
		664	/----------------------------------------------------------------------/
		665	/* Getvalue returns the value of the semaphore (>=0). If someone is */
		666	/* blocked on the semaphore, return the number of process blocked (<0) */
		667	/----------------------------------------------------------------------/
		668	int sem_getvalue(sem_t sem, int sval)
		669	{
		670	PID p;
		671	SYS_FLAGS f;
		672
		673	if (sem < 0 \|\| sem >= SEM_NSEMS_MAX \|\| !sem_table[*sem].used) {
		674	errno = EINVAL;
		675	return -1;
		676	}
		677
		678	f = kern_fsave();
		679
		680	if (iq_isempty(&sem_table[*sem].blocked))
		681	/* the sem is free */
		682	sval = sem_table[sem].count;
		683	else {
		684	/* the sem is busy */
		685	*sval = 0;
		686	p = iq_query_first(&sem_table[*sem].blocked);
		687	do {
		688	(*sval)--;
		689	p = iq_query_next(p, &sem_table[*sem].blocked);
		690	} while (p != NIL);
		691	}
		692
		693	kern_frestore(f);
		694	return 0;
		695	}
		696
		697
		698	/----------------------------------------------------------------------/
		699	/* this function returns 1 if the task is blocked on a semaphore */
		700	/----------------------------------------------------------------------/
		701	int isBlocked(PID i)
		702	{
		703	if (proc_table[i].status == WAIT_SEM) return 1;
		704	else return 0;
		705	}
		706

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