WebSVN – HelenOS-historic – Diff – /kernel/trunk/generic/src/synch/waitq.c


/*
 * Copyright (C) 2001-2004 Jakub Jermar
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - 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.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
 */
 
#include <synch/waitq.h>
#include <synch/synch.h>
#include <synch/spinlock.h>
#include <proc/thread.h>
#include <proc/scheduler.h>
#include <arch/asm.h>
#include <arch/types.h>
#include <typedefs.h>
#include <time/timeout.h>
#include <arch.h>
#include <context.h>
#include <adt/list.h>
 
static void waitq_timeouted_sleep(void *data);
 
/** Initialize wait queue
 *
 * Initialize wait queue.
 *
 * @param wq Pointer to wait queue to be initialized.
 */
void waitq_initialize(waitq_t *wq)
{
    spinlock_initialize(&wq->lock, "waitq_lock");
    list_initialize(&wq->head);
    wq->missed_wakeups = 0;
}
 
/** Handle timeout during waitq_sleep_timeout() call
 *
 * This routine is called when waitq_sleep_timeout() timeouts.
 * Interrupts are disabled.
 *
 * It is supposed to try to remove 'its' thread from the wait queue;
 * it can eventually fail to achieve this goal when these two events
 * overlap. In that case it behaves just as though there was no
 * timeout at all.
 *
 * @param data Pointer to the thread that called waitq_sleep_timeout().
 */
void waitq_timeouted_sleep(void *data)
{
    thread_t *t = (thread_t *) data;
    waitq_t *wq;
    bool do_wakeup = false;
 
    spinlock_lock(&threads_lock);
    if (!thread_exists(t))
        goto out;
 
grab_locks:
    spinlock_lock(&t->lock);
    if ((wq = t->sleep_queue)) {        /* assignment */
        if (!spinlock_trylock(&wq->lock)) {
            spinlock_unlock(&t->lock);
            goto grab_locks;    /* avoid deadlock */
        }
 
        list_remove(&t->wq_link);
        t->saved_context = t->sleep_timeout_context;
        do_wakeup = true;
       
        spinlock_unlock(&wq->lock);
        t->sleep_queue = NULL;
    }
   
    t->timeout_pending = false;
    spinlock_unlock(&t->lock);
   
    if (do_wakeup)
        thread_ready(t);
 
out:
    spinlock_unlock(&threads_lock);
}
 
/** Interrupt sleeping thread.
 *
 * This routine attempts to interrupt a thread from its sleep in a waitqueue.
 * If the thread is not found sleeping, no action is taken.
 *
 * @param t Thread to be interrupted.
 */
void waitq_interrupt_sleep(thread_t *t)
{
    waitq_t *wq;
    bool do_wakeup = false;
    ipl_t ipl;
 
    ipl = interrupts_disable();
    spinlock_lock(&threads_lock);
    if (!thread_exists(t))
        goto out;
 
grab_locks:
    spinlock_lock(&t->lock);
    if ((wq = t->sleep_queue)) {        /* assignment */
        if (!spinlock_trylock(&wq->lock)) {
            spinlock_unlock(&t->lock);
            goto grab_locks;    /* avoid deadlock */
        }
 
        list_remove(&t->wq_link);
        t->saved_context = t->sleep_interruption_context;
        do_wakeup = true;
       
        spinlock_unlock(&wq->lock);
        t->sleep_queue = NULL;
    }
    spinlock_unlock(&t->lock);
 
    if (do_wakeup)
        thread_ready(t);
 
out:
    spinlock_unlock(&threads_lock);
    interrupts_restore(ipl);
}
 
 
/** Sleep until either wakeup, timeout or interruption occurs
 *
 * This is a sleep implementation which allows itself to be
 * interrupted from the sleep, restoring a failover context.
 *
 * Sleepers are organised in FIFO fashion in a structure called wait queue.
 *
 * This function is really basic in that other functions as waitq_sleep()
 * and all the *_timeout() functions use it.
 *
 * @param wq Pointer to wait queue.
 * @param usec Timeout in microseconds.
 * @param nonblocking Blocking vs. non-blocking operation mode switch.
 *
 * If usec is greater than zero, regardless of the value of nonblocking,
 * the call will not return until either timeout or wakeup comes.
 *
 * If usec is zero and nonblocking is zero (false), the call
 * will not return until wakeup comes.
 *
 * If usec is zero and nonblocking is non-zero (true), the call will
 * immediately return, reporting either success or failure.
 *
 * @return Returns one of: ESYNCH_WOULD_BLOCK, ESYNCH_TIMEOUT,
 *         ESYNCH_OK_ATOMIC, ESYNCH_OK_BLOCKED.
 *
 * ESYNCH_WOULD_BLOCK means that the sleep failed because at the time
 * of the call there was no pending wakeup.
 *
 * ESYNCH_TIMEOUT means that the sleep timed out.
 *
 * ESYNCH_INTERRUPTED means that somebody interrupted the sleeping thread.
 *
 * ESYNCH_OK_ATOMIC means that the sleep succeeded and that there was
 * a pending wakeup at the time of the call. The caller was not put
 * asleep at all.
 *
 * ESYNCH_OK_BLOCKED means that the sleep succeeded; the full sleep was
 * attempted.
 */
int waitq_sleep_timeout(waitq_t *wq, __u32 usec, int nonblocking)
{
    volatile ipl_t ipl; /* must be live after context_restore() */
   
   
restart:
    ipl = interrupts_disable();
   
    /*
     * Busy waiting for a delayed timeout.
     * This is an important fix for the race condition between
     * a delayed timeout and a next call to waitq_sleep_timeout().
     * Simply, the thread is not allowed to go to sleep if
     * there are timeouts in progress.
     */
    spinlock_lock(&THREAD->lock);
    if (THREAD->timeout_pending) {
        spinlock_unlock(&THREAD->lock);
        interrupts_restore(ipl);       
        goto restart;
    }
    spinlock_unlock(&THREAD->lock);
   
    spinlock_lock(&wq->lock);
   
    /* checks whether to go to sleep at all */
    if (wq->missed_wakeups) {
        wq->missed_wakeups--;
        spinlock_unlock(&wq->lock);
        interrupts_restore(ipl);
        return ESYNCH_OK_ATOMIC;
    }
    else {
        if (nonblocking && (usec == 0)) {
            /* return immediatelly instead of going to sleep */
            spinlock_unlock(&wq->lock);
            interrupts_restore(ipl);
            return ESYNCH_WOULD_BLOCK;
        }
    }
   
    /*
     * Now we are firmly decided to go to sleep.
     */
    spinlock_lock(&THREAD->lock);
 
    /*
     * Set context that will be restored if the sleep
     * of this thread is ever interrupted.
     */
    if (!context_save(&THREAD->sleep_interruption_context)) {
        /* Short emulation of scheduler() return code. */
        spinlock_unlock(&THREAD->lock);
        interrupts_restore(ipl);
        return ESYNCH_INTERRUPTED;
    }
 
    if (usec) {
        /* We use the timeout variant. */
        if (!context_save(&THREAD->sleep_timeout_context)) {
            /* Short emulation of scheduler() return code. */
            spinlock_unlock(&THREAD->lock);
            interrupts_restore(ipl);
            return ESYNCH_TIMEOUT;
        }
        THREAD->timeout_pending = true;
        timeout_register(&THREAD->sleep_timeout, (__u64) usec, waitq_timeouted_sleep, THREAD);
    }
 
    list_append(&THREAD->wq_link, &wq->head);
 
    /*
     * Suspend execution.
     */
    THREAD->state = Sleeping;
    THREAD->sleep_queue = wq;
 
    spinlock_unlock(&THREAD->lock);
 
    scheduler();    /* wq->lock is released in scheduler_separated_stack() */
    interrupts_restore(ipl);
   
    return ESYNCH_OK_BLOCKED;
}
 
 
/** Wake up first thread sleeping in a wait queue
 *
 * Wake up first thread sleeping in a wait queue.
 * This is the SMP- and IRQ-safe wrapper meant for
 * general use.
 *
 * Besides its 'normal' wakeup operation, it attempts
 * to unregister possible timeout.
 *
 * @param wq Pointer to wait queue.
 * @param all If this is non-zero, all sleeping threads
 *        will be woken up and missed count will be zeroed.
 */
void waitq_wakeup(waitq_t *wq, bool all)
{
    ipl_t ipl;
 
    ipl = interrupts_disable();
    spinlock_lock(&wq->lock);
 
    _waitq_wakeup_unsafe(wq, all);
 
    spinlock_unlock(&wq->lock);
    interrupts_restore(ipl);   
}
 
/** Internal SMP- and IRQ-unsafe version of waitq_wakeup()
 *
 * This is the internal SMP- and IRQ-unsafe version
 * of waitq_wakeup(). It assumes wq->lock is already
 * locked and interrupts are already disabled.
 *
 * @param wq Pointer to wait queue.
 * @param all If this is non-zero, all sleeping threads
 *        will be woken up and missed count will be zeroed.
 */
void _waitq_wakeup_unsafe(waitq_t *wq, bool all)
{
    thread_t *t;
 
loop:  
    if (list_empty(&wq->head)) {
        wq->missed_wakeups++;
        if (all)
            wq->missed_wakeups = 0;
        return;
    }
 
    t = list_get_instance(wq->head.next, thread_t, wq_link);
   
    list_remove(&t->wq_link);
    spinlock_lock(&t->lock);
    if (t->timeout_pending && timeout_unregister(&t->sleep_timeout))
        t->timeout_pending = false;
    t->sleep_queue = NULL;
    spinlock_unlock(&t->lock);
 
    thread_ready(t);
 
    if (all)
        goto loop;
}
 

Rev 1156	Rev 1158
1	/*	1	/*
2	* Copyright (C) 2001-2004 Jakub Jermar	2	* Copyright (C) 2001-2004 Jakub Jermar
3	* All rights reserved.	3	* All rights reserved.
4	*	4	*
5	* Redistribution and use in source and binary forms, with or without	5	* Redistribution and use in source and binary forms, with or without
6	* modification, are permitted provided that the following conditions	6	* modification, are permitted provided that the following conditions
7	* are met:	7	* are met:
8	*	8	*
9	* - Redistributions of source code must retain the above copyright	9	* - Redistributions of source code must retain the above copyright
10	* notice, this list of conditions and the following disclaimer.	10	* notice, this list of conditions and the following disclaimer.
11	* - Redistributions in binary form must reproduce the above copyright	11	* - Redistributions in binary form must reproduce the above copyright
12	* notice, this list of conditions and the following disclaimer in the	12	* notice, this list of conditions and the following disclaimer in the
13	* documentation and/or other materials provided with the distribution.	13	* documentation and/or other materials provided with the distribution.
14	* - The name of the author may not be used to endorse or promote products	14	* - The name of the author may not be used to endorse or promote products
15	* derived from this software without specific prior written permission.	15	* derived from this software without specific prior written permission.
16	*	16	*
17	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR	17	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES	18	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.	19	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,	20	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT	21	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,	22	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY	23	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT	24	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF	25	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.	26	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27	*/	27	*/
28		28
29	#include <synch/waitq.h>	29	#include <synch/waitq.h>
30	#include <synch/synch.h>	30	#include <synch/synch.h>
31	#include <synch/spinlock.h>	31	#include <synch/spinlock.h>
32	#include <proc/thread.h>	32	#include <proc/thread.h>
33	#include <proc/scheduler.h>	33	#include <proc/scheduler.h>
34	#include <arch/asm.h>	34	#include <arch/asm.h>
35	#include <arch/types.h>	35	#include <arch/types.h>
36	#include <typedefs.h>	36	#include <typedefs.h>
37	#include <time/timeout.h>	37	#include <time/timeout.h>
38	#include <arch.h>	38	#include <arch.h>
39	#include <context.h>	39	#include <context.h>
40	#include <adt/list.h>	40	#include <adt/list.h>
41		41
42	static void waitq_timeouted_sleep(void *data);	42	static void waitq_timeouted_sleep(void *data);
43		43
44	/** Initialize wait queue	44	/** Initialize wait queue
45	*	45	*
46	* Initialize wait queue.	46	* Initialize wait queue.
47	*	47	*
48	* @param wq Pointer to wait queue to be initialized.	48	* @param wq Pointer to wait queue to be initialized.
49	*/	49	*/
50	void waitq_initialize(waitq_t *wq)	50	void waitq_initialize(waitq_t *wq)
51	{	51	{
52	spinlock_initialize(&wq->lock, "waitq_lock");	52	spinlock_initialize(&wq->lock, "waitq_lock");
53	list_initialize(&wq->head);	53	list_initialize(&wq->head);
54	wq->missed_wakeups = 0;	54	wq->missed_wakeups = 0;
55	}	55	}
56		56
57	/** Handle timeout during waitq_sleep_timeout() call	57	/** Handle timeout during waitq_sleep_timeout() call
58	*	58	*
59	* This routine is called when waitq_sleep_timeout() timeouts.	59	* This routine is called when waitq_sleep_timeout() timeouts.
60	* Interrupts are disabled.	60	* Interrupts are disabled.
61	*	61	*
62	* It is supposed to try to remove 'its' thread from the wait queue;	62	* It is supposed to try to remove 'its' thread from the wait queue;
63	* it can eventually fail to achieve this goal when these two events	63	* it can eventually fail to achieve this goal when these two events
64	* overlap. In that case it behaves just as though there was no	64	* overlap. In that case it behaves just as though there was no
65	* timeout at all.	65	* timeout at all.
66	*	66	*
67	* @param data Pointer to the thread that called waitq_sleep_timeout().	67	* @param data Pointer to the thread that called waitq_sleep_timeout().
68	*/	68	*/
69	void waitq_timeouted_sleep(void *data)	69	void waitq_timeouted_sleep(void *data)
70	{	70	{
71	thread_t t = (thread_t ) data;	71	thread_t t = (thread_t ) data;
72	waitq_t *wq;	72	waitq_t *wq;
73	bool do_wakeup = false;	73	bool do_wakeup = false;
74		74
75	spinlock_lock(&threads_lock);	75	spinlock_lock(&threads_lock);
76	if (!list_member(&t->threads_link, &threads_head))	76	if (!thread_exists(t))
77	goto out;	77	goto out;
78		78
79	grab_locks:	79	grab_locks:
80	spinlock_lock(&t->lock);	80	spinlock_lock(&t->lock);
81	if ((wq = t->sleep_queue)) { /* assignment */	81	if ((wq = t->sleep_queue)) { /* assignment */
82	if (!spinlock_trylock(&wq->lock)) {	82	if (!spinlock_trylock(&wq->lock)) {
83	spinlock_unlock(&t->lock);	83	spinlock_unlock(&t->lock);
84	goto grab_locks; /* avoid deadlock */	84	goto grab_locks; /* avoid deadlock */
85	}	85	}
86		86
87	list_remove(&t->wq_link);	87	list_remove(&t->wq_link);
88	t->saved_context = t->sleep_timeout_context;	88	t->saved_context = t->sleep_timeout_context;
89	do_wakeup = true;	89	do_wakeup = true;
90		90
91	spinlock_unlock(&wq->lock);	91	spinlock_unlock(&wq->lock);
92	t->sleep_queue = NULL;	92	t->sleep_queue = NULL;
93	}	93	}
94		94
95	t->timeout_pending = false;	95	t->timeout_pending = false;
96	spinlock_unlock(&t->lock);	96	spinlock_unlock(&t->lock);
97		97
98	if (do_wakeup)	98	if (do_wakeup)
99	thread_ready(t);	99	thread_ready(t);
100		100
101	out:	101	out:
102	spinlock_unlock(&threads_lock);	102	spinlock_unlock(&threads_lock);
103	}	103	}
104		104
105	/** Interrupt sleeping thread.	105	/** Interrupt sleeping thread.
106	*	106	*
107	* This routine attempts to interrupt a thread from its sleep in a waitqueue.	107	* This routine attempts to interrupt a thread from its sleep in a waitqueue.
108	* If the thread is not found sleeping, no action is taken.	108	* If the thread is not found sleeping, no action is taken.
109	*	109	*
110	* @param t Thread to be interrupted.	110	* @param t Thread to be interrupted.
111	*/	111	*/
112	void waitq_interrupt_sleep(thread_t *t)	112	void waitq_interrupt_sleep(thread_t *t)
113	{	113	{
114	waitq_t *wq;	114	waitq_t *wq;
115	bool do_wakeup = false;	115	bool do_wakeup = false;
116	ipl_t ipl;	116	ipl_t ipl;
117		117
118	ipl = interrupts_disable();	118	ipl = interrupts_disable();
119	spinlock_lock(&threads_lock);	119	spinlock_lock(&threads_lock);
120	if (!list_member(&t->threads_link, &threads_head))	120	if (!thread_exists(t))
121	goto out;	121	goto out;
122		122
123	grab_locks:	123	grab_locks:
124	spinlock_lock(&t->lock);	124	spinlock_lock(&t->lock);
125	if ((wq = t->sleep_queue)) { /* assignment */	125	if ((wq = t->sleep_queue)) { /* assignment */
126	if (!spinlock_trylock(&wq->lock)) {	126	if (!spinlock_trylock(&wq->lock)) {
127	spinlock_unlock(&t->lock);	127	spinlock_unlock(&t->lock);
128	goto grab_locks; /* avoid deadlock */	128	goto grab_locks; /* avoid deadlock */
129	}	129	}
130		130
131	list_remove(&t->wq_link);	131	list_remove(&t->wq_link);
132	t->saved_context = t->sleep_interruption_context;	132	t->saved_context = t->sleep_interruption_context;
133	do_wakeup = true;	133	do_wakeup = true;
134		134
135	spinlock_unlock(&wq->lock);	135	spinlock_unlock(&wq->lock);
136	t->sleep_queue = NULL;	136	t->sleep_queue = NULL;
137	}	137	}
138	spinlock_unlock(&t->lock);	138	spinlock_unlock(&t->lock);
139		139
140	if (do_wakeup)	140	if (do_wakeup)
141	thread_ready(t);	141	thread_ready(t);
142		142
143	out:	143	out:
144	spinlock_unlock(&threads_lock);	144	spinlock_unlock(&threads_lock);
145	interrupts_restore(ipl);	145	interrupts_restore(ipl);
146	}	146	}
147		147
148		148
149	/** Sleep until either wakeup, timeout or interruption occurs	149	/** Sleep until either wakeup, timeout or interruption occurs
150	*	150	*
151	* This is a sleep implementation which allows itself to be	151	* This is a sleep implementation which allows itself to be
152	* interrupted from the sleep, restoring a failover context.	152	* interrupted from the sleep, restoring a failover context.
153	*	153	*
154	* Sleepers are organised in FIFO fashion in a structure called wait queue.	154	* Sleepers are organised in FIFO fashion in a structure called wait queue.
155	*	155	*
156	* This function is really basic in that other functions as waitq_sleep()	156	* This function is really basic in that other functions as waitq_sleep()
157	* and all the *_timeout() functions use it.	157	* and all the *_timeout() functions use it.
158	*	158	*
159	* @param wq Pointer to wait queue.	159	* @param wq Pointer to wait queue.
160	* @param usec Timeout in microseconds.	160	* @param usec Timeout in microseconds.
161	* @param nonblocking Blocking vs. non-blocking operation mode switch.	161	* @param nonblocking Blocking vs. non-blocking operation mode switch.
162	*	162	*
163	* If usec is greater than zero, regardless of the value of nonblocking,	163	* If usec is greater than zero, regardless of the value of nonblocking,
164	* the call will not return until either timeout or wakeup comes.	164	* the call will not return until either timeout or wakeup comes.
165	*	165	*
166	* If usec is zero and nonblocking is zero (false), the call	166	* If usec is zero and nonblocking is zero (false), the call
167	* will not return until wakeup comes.	167	* will not return until wakeup comes.
168	*	168	*
169	* If usec is zero and nonblocking is non-zero (true), the call will	169	* If usec is zero and nonblocking is non-zero (true), the call will
170	* immediately return, reporting either success or failure.	170	* immediately return, reporting either success or failure.
171	*	171	*
172	* @return Returns one of: ESYNCH_WOULD_BLOCK, ESYNCH_TIMEOUT,	172	* @return Returns one of: ESYNCH_WOULD_BLOCK, ESYNCH_TIMEOUT,
173	* ESYNCH_OK_ATOMIC, ESYNCH_OK_BLOCKED.	173	* ESYNCH_OK_ATOMIC, ESYNCH_OK_BLOCKED.
174	*	174	*
175	* ESYNCH_WOULD_BLOCK means that the sleep failed because at the time	175	* ESYNCH_WOULD_BLOCK means that the sleep failed because at the time
176	* of the call there was no pending wakeup.	176	* of the call there was no pending wakeup.
177	*	177	*
178	* ESYNCH_TIMEOUT means that the sleep timed out.	178	* ESYNCH_TIMEOUT means that the sleep timed out.
179	*	179	*
180	* ESYNCH_INTERRUPTED means that somebody interrupted the sleeping thread.	180	* ESYNCH_INTERRUPTED means that somebody interrupted the sleeping thread.
181	*	181	*
182	* ESYNCH_OK_ATOMIC means that the sleep succeeded and that there was	182	* ESYNCH_OK_ATOMIC means that the sleep succeeded and that there was
183	* a pending wakeup at the time of the call. The caller was not put	183	* a pending wakeup at the time of the call. The caller was not put
184	* asleep at all.	184	* asleep at all.
185	*	185	*
186	* ESYNCH_OK_BLOCKED means that the sleep succeeded; the full sleep was	186	* ESYNCH_OK_BLOCKED means that the sleep succeeded; the full sleep was
187	* attempted.	187	* attempted.
188	*/	188	*/
189	int waitq_sleep_timeout(waitq_t *wq, __u32 usec, int nonblocking)	189	int waitq_sleep_timeout(waitq_t *wq, __u32 usec, int nonblocking)
190	{	190	{
191	volatile ipl_t ipl; /* must be live after context_restore() */	191	volatile ipl_t ipl; /* must be live after context_restore() */
192		192
193		193
194	restart:	194	restart:
195	ipl = interrupts_disable();	195	ipl = interrupts_disable();
196		196
197	/*	197	/*
198	* Busy waiting for a delayed timeout.	198	* Busy waiting for a delayed timeout.
199	* This is an important fix for the race condition between	199	* This is an important fix for the race condition between
200	* a delayed timeout and a next call to waitq_sleep_timeout().	200	* a delayed timeout and a next call to waitq_sleep_timeout().
201	* Simply, the thread is not allowed to go to sleep if	201	* Simply, the thread is not allowed to go to sleep if
202	* there are timeouts in progress.	202	* there are timeouts in progress.
203	*/	203	*/
204	spinlock_lock(&THREAD->lock);	204	spinlock_lock(&THREAD->lock);
205	if (THREAD->timeout_pending) {	205	if (THREAD->timeout_pending) {
206	spinlock_unlock(&THREAD->lock);	206	spinlock_unlock(&THREAD->lock);
207	interrupts_restore(ipl);	207	interrupts_restore(ipl);
208	goto restart;	208	goto restart;
209	}	209	}
210	spinlock_unlock(&THREAD->lock);	210	spinlock_unlock(&THREAD->lock);
211		211
212	spinlock_lock(&wq->lock);	212	spinlock_lock(&wq->lock);
213		213
214	/* checks whether to go to sleep at all */	214	/* checks whether to go to sleep at all */
215	if (wq->missed_wakeups) {	215	if (wq->missed_wakeups) {
216	wq->missed_wakeups--;	216	wq->missed_wakeups--;
217	spinlock_unlock(&wq->lock);	217	spinlock_unlock(&wq->lock);
218	interrupts_restore(ipl);	218	interrupts_restore(ipl);
219	return ESYNCH_OK_ATOMIC;	219	return ESYNCH_OK_ATOMIC;
220	}	220	}
221	else {	221	else {
222	if (nonblocking && (usec == 0)) {	222	if (nonblocking && (usec == 0)) {
223	/* return immediatelly instead of going to sleep */	223	/* return immediatelly instead of going to sleep */
224	spinlock_unlock(&wq->lock);	224	spinlock_unlock(&wq->lock);
225	interrupts_restore(ipl);	225	interrupts_restore(ipl);
226	return ESYNCH_WOULD_BLOCK;	226	return ESYNCH_WOULD_BLOCK;
227	}	227	}
228	}	228	}
229		229
230	/*	230	/*
231	* Now we are firmly decided to go to sleep.	231	* Now we are firmly decided to go to sleep.
232	*/	232	*/
233	spinlock_lock(&THREAD->lock);	233	spinlock_lock(&THREAD->lock);
234		234
235	/*	235	/*
236	* Set context that will be restored if the sleep	236	* Set context that will be restored if the sleep
237	* of this thread is ever interrupted.	237	* of this thread is ever interrupted.
238	*/	238	*/
239	if (!context_save(&THREAD->sleep_interruption_context)) {	239	if (!context_save(&THREAD->sleep_interruption_context)) {
240	/* Short emulation of scheduler() return code. */	240	/* Short emulation of scheduler() return code. */
241	spinlock_unlock(&THREAD->lock);	241	spinlock_unlock(&THREAD->lock);
242	interrupts_restore(ipl);	242	interrupts_restore(ipl);
243	return ESYNCH_INTERRUPTED;	243	return ESYNCH_INTERRUPTED;
244	}	244	}
245		245
246	if (usec) {	246	if (usec) {
247	/* We use the timeout variant. */	247	/* We use the timeout variant. */
248	if (!context_save(&THREAD->sleep_timeout_context)) {	248	if (!context_save(&THREAD->sleep_timeout_context)) {
249	/* Short emulation of scheduler() return code. */	249	/* Short emulation of scheduler() return code. */
250	spinlock_unlock(&THREAD->lock);	250	spinlock_unlock(&THREAD->lock);
251	interrupts_restore(ipl);	251	interrupts_restore(ipl);
252	return ESYNCH_TIMEOUT;	252	return ESYNCH_TIMEOUT;
253	}	253	}
254	THREAD->timeout_pending = true;	254	THREAD->timeout_pending = true;
255	timeout_register(&THREAD->sleep_timeout, (__u64) usec, waitq_timeouted_sleep, THREAD);	255	timeout_register(&THREAD->sleep_timeout, (__u64) usec, waitq_timeouted_sleep, THREAD);
256	}	256	}
257		257
258	list_append(&THREAD->wq_link, &wq->head);	258	list_append(&THREAD->wq_link, &wq->head);
259		259
260	/*	260	/*
261	* Suspend execution.	261	* Suspend execution.
262	*/	262	*/
263	THREAD->state = Sleeping;	263	THREAD->state = Sleeping;
264	THREAD->sleep_queue = wq;	264	THREAD->sleep_queue = wq;
265		265
266	spinlock_unlock(&THREAD->lock);	266	spinlock_unlock(&THREAD->lock);
267		267
268	scheduler(); /* wq->lock is released in scheduler_separated_stack() */	268	scheduler(); /* wq->lock is released in scheduler_separated_stack() */
269	interrupts_restore(ipl);	269	interrupts_restore(ipl);
270		270
271	return ESYNCH_OK_BLOCKED;	271	return ESYNCH_OK_BLOCKED;
272	}	272	}
273		273
274		274
275	/** Wake up first thread sleeping in a wait queue	275	/** Wake up first thread sleeping in a wait queue
276	*	276	*
277	* Wake up first thread sleeping in a wait queue.	277	* Wake up first thread sleeping in a wait queue.
278	* This is the SMP- and IRQ-safe wrapper meant for	278	* This is the SMP- and IRQ-safe wrapper meant for
279	* general use.	279	* general use.
280	*	280	*
281	* Besides its 'normal' wakeup operation, it attempts	281	* Besides its 'normal' wakeup operation, it attempts
282	* to unregister possible timeout.	282	* to unregister possible timeout.
283	*	283	*
284	* @param wq Pointer to wait queue.	284	* @param wq Pointer to wait queue.
285	* @param all If this is non-zero, all sleeping threads	285	* @param all If this is non-zero, all sleeping threads
286	* will be woken up and missed count will be zeroed.	286	* will be woken up and missed count will be zeroed.
287	*/	287	*/
288	void waitq_wakeup(waitq_t *wq, bool all)	288	void waitq_wakeup(waitq_t *wq, bool all)
289	{	289	{
290	ipl_t ipl;	290	ipl_t ipl;
291		291
292	ipl = interrupts_disable();	292	ipl = interrupts_disable();
293	spinlock_lock(&wq->lock);	293	spinlock_lock(&wq->lock);
294		294
295	_waitq_wakeup_unsafe(wq, all);	295	_waitq_wakeup_unsafe(wq, all);
296		296
297	spinlock_unlock(&wq->lock);	297	spinlock_unlock(&wq->lock);
298	interrupts_restore(ipl);	298	interrupts_restore(ipl);
299	}	299	}
300		300
301	/** Internal SMP- and IRQ-unsafe version of waitq_wakeup()	301	/** Internal SMP- and IRQ-unsafe version of waitq_wakeup()
302	*	302	*
303	* This is the internal SMP- and IRQ-unsafe version	303	* This is the internal SMP- and IRQ-unsafe version
304	* of waitq_wakeup(). It assumes wq->lock is already	304	* of waitq_wakeup(). It assumes wq->lock is already
305	* locked and interrupts are already disabled.	305	* locked and interrupts are already disabled.
306	*	306	*
307	* @param wq Pointer to wait queue.	307	* @param wq Pointer to wait queue.
308	* @param all If this is non-zero, all sleeping threads	308	* @param all If this is non-zero, all sleeping threads
309	* will be woken up and missed count will be zeroed.	309	* will be woken up and missed count will be zeroed.
310	*/	310	*/
311	void _waitq_wakeup_unsafe(waitq_t *wq, bool all)	311	void _waitq_wakeup_unsafe(waitq_t *wq, bool all)
312	{	312	{
313	thread_t *t;	313	thread_t *t;
314		314
315	loop:	315	loop:
316	if (list_empty(&wq->head)) {	316	if (list_empty(&wq->head)) {
317	wq->missed_wakeups++;	317	wq->missed_wakeups++;
318	if (all)	318	if (all)
319	wq->missed_wakeups = 0;	319	wq->missed_wakeups = 0;
320	return;	320	return;
321	}	321	}
322		322
323	t = list_get_instance(wq->head.next, thread_t, wq_link);	323	t = list_get_instance(wq->head.next, thread_t, wq_link);
324		324
325	list_remove(&t->wq_link);	325	list_remove(&t->wq_link);
326	spinlock_lock(&t->lock);	326	spinlock_lock(&t->lock);
327	if (t->timeout_pending && timeout_unregister(&t->sleep_timeout))	327	if (t->timeout_pending && timeout_unregister(&t->sleep_timeout))
328	t->timeout_pending = false;	328	t->timeout_pending = false;
329	t->sleep_queue = NULL;	329	t->sleep_queue = NULL;
330	spinlock_unlock(&t->lock);	330	spinlock_unlock(&t->lock);
331		331
332	thread_ready(t);	332	thread_ready(t);
333		333
334	if (all)	334	if (all)
335	goto loop;	335	goto loop;
336	}	336	}
337		337

Subversion Repositories HelenOS-historic

(root)/kernel/trunk/generic/src/synch/waitq.c – Rev 1156 → 1158