WebSVN – HelenOS – Diff – /branches/dynload/kernel/generic/src/synch/spinlock.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.
 */
 
/** @addtogroup sync
 * @{
 */
 
/**
 * @file
 * @brief Spinlocks.
 */
 
#include <synch/spinlock.h>
#include <atomic.h>
#include <arch/barrier.h>
#include <arch.h>
#include <preemption.h>
#include <print.h>
#include <debug.h>
#include <symtab.h>
 
#ifdef CONFIG_FB
#include <genarch/fb/fb.h>
#endif
 
#ifdef CONFIG_SMP
 
/** Initialize spinlock
 *
 * Initialize spinlock.
 *
 * @param sl Pointer to spinlock_t structure.
 */
void spinlock_initialize(spinlock_t *sl, char *name)
{
    atomic_set(&sl->val, 0);
#ifdef CONFIG_DEBUG_SPINLOCK
    sl->name = name;
#endif  
}
 
/** Lock spinlock
 *
 * Lock spinlock.
 * This version has limitted ability to report
 * possible occurence of deadlock.
 *
 * @param sl Pointer to spinlock_t structure.
 */
#ifdef CONFIG_DEBUG_SPINLOCK
void spinlock_lock_debug(spinlock_t *sl)
{
    size_t i = 0;
    bool deadlock_reported = false;
 
    preemption_disable();
    while (test_and_set(&sl->val)) {
 
        /*
         * We need to be careful about printf_lock and fb_lock.
         * Both of them are used to report deadlocks via
         * printf() and fb_putchar().
         *
         * We trust our code that there is no possible deadlock
         * caused by these two locks (except when an exception
         * is triggered for instance by printf() or fb_putchar()).
         * However, we encountered false positives caused by very
         * slow VESA framebuffer interaction (especially when
         * run in a simulator) that caused problems with both
         * printf_lock and fb_lock.
         *
         * Possible deadlocks on both printf_lock and fb_lock
         * are therefore not reported as they would cause an
         * infinite recursion.
         */
        if (sl == &printf_lock)
            continue;
#ifdef CONFIG_FB
        if (sl == &fb_lock)
            continue;
#endif
        if (i++ > DEADLOCK_THRESHOLD) {
            printf("cpu%u: looping on spinlock %" PRIp ":%s, "
                "caller=%" PRIp "(%s)\n", CPU->id, sl, sl->name,
                CALLER, symtab_fmt_name_lookup(CALLER));
           
            i = 0;
            deadlock_reported = true;
        }
    }
 
    if (deadlock_reported)
        printf("cpu%u: not deadlocked\n", CPU->id);
 
    /*
     * Prevent critical section code from bleeding out this way up.
     */
    CS_ENTER_BARRIER();
}
#endif
 
/** Lock spinlock conditionally
 *
 * Lock spinlock conditionally.
 * If the spinlock is not available at the moment,
 * signal failure.
 *
 * @param sl Pointer to spinlock_t structure.
 *
 * @return Zero on failure, non-zero otherwise.
 */
int spinlock_trylock(spinlock_t *sl)
{
    int rc;
   
    preemption_disable();
    rc = !test_and_set(&sl->val);
 
    /*
     * Prevent critical section code from bleeding out this way up.
     */
    CS_ENTER_BARRIER();
 
    if (!rc)
        preemption_enable();
   
    return rc;
}
 
#endif
 
/** @}
 */
 

Rev 4348	Rev 4691
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	/** @addtogroup sync	29	/** @addtogroup sync
30	* @{	30	* @{
31	*/	31	*/
32		32
33	/**	33	/**
34	* @file	34	* @file
35	* @brief Spinlocks.	35	* @brief Spinlocks.
36	*/	36	*/
37		37
38	#include <synch/spinlock.h>	38	#include <synch/spinlock.h>
39	#include <atomic.h>	39	#include <atomic.h>
40	#include <arch/barrier.h>	40	#include <arch/barrier.h>
41	#include <arch.h>	41	#include <arch.h>
42	#include <preemption.h>	42	#include <preemption.h>
43	#include <print.h>	43	#include <print.h>
44	#include <debug.h>	44	#include <debug.h>
45	#include <symtab.h>	45	#include <symtab.h>
46		46
47	#ifdef CONFIG_FB	47	#ifdef CONFIG_FB
48	#include <genarch/fb/fb.h>	48	#include <genarch/fb/fb.h>
49	#endif	49	#endif
50		50
51	#ifdef CONFIG_SMP	51	#ifdef CONFIG_SMP
52		52
53	/** Initialize spinlock	53	/** Initialize spinlock
54	*	54	*
55	* Initialize spinlock.	55	* Initialize spinlock.
56	*	56	*
57	* @param sl Pointer to spinlock_t structure.	57	* @param sl Pointer to spinlock_t structure.
58	*/	58	*/
59	void spinlock_initialize(spinlock_t sl, char name)	59	void spinlock_initialize(spinlock_t sl, char name)
60	{	60	{
61	atomic_set(&sl->val, 0);	61	atomic_set(&sl->val, 0);
62	#ifdef CONFIG_DEBUG_SPINLOCK	62	#ifdef CONFIG_DEBUG_SPINLOCK
63	sl->name = name;	63	sl->name = name;
64	#endif	64	#endif
65	}	65	}
66		66
67	/** Lock spinlock	67	/** Lock spinlock
68	*	68	*
69	* Lock spinlock.	69	* Lock spinlock.
70	* This version has limitted ability to report	70	* This version has limitted ability to report
71	* possible occurence of deadlock.	71	* possible occurence of deadlock.
72	*	72	*
73	* @param sl Pointer to spinlock_t structure.	73	* @param sl Pointer to spinlock_t structure.
74	*/	74	*/
75	#ifdef CONFIG_DEBUG_SPINLOCK	75	#ifdef CONFIG_DEBUG_SPINLOCK
76	void spinlock_lock_debug(spinlock_t *sl)	76	void spinlock_lock_debug(spinlock_t *sl)
77	{	77	{
78	count_t i = 0;	78	size_t i = 0;
79	bool deadlock_reported = false;	79	bool deadlock_reported = false;
80		80
81	preemption_disable();	81	preemption_disable();
82	while (test_and_set(&sl->val)) {	82	while (test_and_set(&sl->val)) {
83		83
84	/*	84	/*
85	* We need to be careful about printf_lock and fb_lock.	85	* We need to be careful about printf_lock and fb_lock.
86	* Both of them are used to report deadlocks via	86	* Both of them are used to report deadlocks via
87	* printf() and fb_putchar().	87	* printf() and fb_putchar().
88	*	88	*
89	* We trust our code that there is no possible deadlock	89	* We trust our code that there is no possible deadlock
90	* caused by these two locks (except when an exception	90	* caused by these two locks (except when an exception
91	* is triggered for instance by printf() or fb_putchar()).	91	* is triggered for instance by printf() or fb_putchar()).
92	* However, we encountered false positives caused by very	92	* However, we encountered false positives caused by very
93	* slow VESA framebuffer interaction (especially when	93	* slow VESA framebuffer interaction (especially when
94	* run in a simulator) that caused problems with both	94	* run in a simulator) that caused problems with both
95	* printf_lock and fb_lock.	95	* printf_lock and fb_lock.
96	*	96	*
97	* Possible deadlocks on both printf_lock and fb_lock	97	* Possible deadlocks on both printf_lock and fb_lock
98	* are therefore not reported as they would cause an	98	* are therefore not reported as they would cause an
99	* infinite recursion.	99	* infinite recursion.
100	*/	100	*/
101	if (sl == &printf_lock)	101	if (sl == &printf_lock)
102	continue;	102	continue;
103	#ifdef CONFIG_FB	103	#ifdef CONFIG_FB
104	if (sl == &fb_lock)	104	if (sl == &fb_lock)
105	continue;	105	continue;
106	#endif	106	#endif
107	if (i++ > DEADLOCK_THRESHOLD) {	107	if (i++ > DEADLOCK_THRESHOLD) {
108	printf("cpu%u: looping on spinlock %" PRIp ":%s, "	108	printf("cpu%u: looping on spinlock %" PRIp ":%s, "
109	"caller=%" PRIp "(%s)\n", CPU->id, sl, sl->name,	109	"caller=%" PRIp "(%s)\n", CPU->id, sl, sl->name,
110	CALLER, symtab_fmt_name_lookup(CALLER));	110	CALLER, symtab_fmt_name_lookup(CALLER));
111		111
112	i = 0;	112	i = 0;
113	deadlock_reported = true;	113	deadlock_reported = true;
114	}	114	}
115	}	115	}
116		116
117	if (deadlock_reported)	117	if (deadlock_reported)
118	printf("cpu%u: not deadlocked\n", CPU->id);	118	printf("cpu%u: not deadlocked\n", CPU->id);
119		119
120	/*	120	/*
121	* Prevent critical section code from bleeding out this way up.	121	* Prevent critical section code from bleeding out this way up.
122	*/	122	*/
123	CS_ENTER_BARRIER();	123	CS_ENTER_BARRIER();
124	}	124	}
125	#endif	125	#endif
126		126
127	/** Lock spinlock conditionally	127	/** Lock spinlock conditionally
128	*	128	*
129	* Lock spinlock conditionally.	129	* Lock spinlock conditionally.
130	* If the spinlock is not available at the moment,	130	* If the spinlock is not available at the moment,
131	* signal failure.	131	* signal failure.
132	*	132	*
133	* @param sl Pointer to spinlock_t structure.	133	* @param sl Pointer to spinlock_t structure.
134	*	134	*
135	* @return Zero on failure, non-zero otherwise.	135	* @return Zero on failure, non-zero otherwise.
136	*/	136	*/
137	int spinlock_trylock(spinlock_t *sl)	137	int spinlock_trylock(spinlock_t *sl)
138	{	138	{
139	int rc;	139	int rc;
140		140
141	preemption_disable();	141	preemption_disable();
142	rc = !test_and_set(&sl->val);	142	rc = !test_and_set(&sl->val);
143		143
144	/*	144	/*
145	* Prevent critical section code from bleeding out this way up.	145	* Prevent critical section code from bleeding out this way up.
146	*/	146	*/
147	CS_ENTER_BARRIER();	147	CS_ENTER_BARRIER();
148		148
149	if (!rc)	149	if (!rc)
150	preemption_enable();	150	preemption_enable();
151		151
152	return rc;	152	return rc;
153	}	153	}
154		154
155	#endif	155	#endif
156		156
157	/** @}	157	/** @}
158	*/	158	*/
159		159

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(root)/branches/dynload/kernel/generic/src/synch/spinlock.c – Rev 4348 → 4691