WebSVN – HelenOS – Diff – /branches/dd/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)
{
    count_t i = 0;
    char *symbol;
    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,
 
                CPU->id, sl, sl->name, CALLER);
            symbol = get_symtab_entry(CALLER);
            if (symbol)
                printf("(%s)", symbol);
            printf("\n");
            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 3022	Rev 4055
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	count_t i = 0;
79	char *symbol;	79	char *symbol;
80	bool deadlock_reported = false;	80	bool deadlock_reported = false;
81		81
82	preemption_disable();	82	preemption_disable();
83	while (test_and_set(&sl->val)) {	83	while (test_and_set(&sl->val)) {
84		84
85	/*	85	/*
86	* We need to be careful about printf_lock and fb_lock.	86	* We need to be careful about printf_lock and fb_lock.
87	* Both of them are used to report deadlocks via	87	* Both of them are used to report deadlocks via
88	* printf() and fb_putchar().	88	* printf() and fb_putchar().
89	*	89	*
90	* We trust our code that there is no possible deadlock	90	* We trust our code that there is no possible deadlock
91	* caused by these two locks (except when an exception	91	* caused by these two locks (except when an exception
92	* is triggered for instance by printf() or fb_putchar()).	92	* is triggered for instance by printf() or fb_putchar()).
93	* However, we encountered false positives caused by very	93	* However, we encountered false positives caused by very
94	* slow VESA framebuffer interaction (especially when	94	* slow VESA framebuffer interaction (especially when
95	* run in a simulator) that caused problems with both	95	* run in a simulator) that caused problems with both
96	* printf_lock and fb_lock.	96	* printf_lock and fb_lock.
97	*	97	*
98	* Possible deadlocks on both printf_lock and fb_lock	98	* Possible deadlocks on both printf_lock and fb_lock
99	* are therefore not reported as they would cause an	99	* are therefore not reported as they would cause an
100	* infinite recursion.	100	* infinite recursion.
101	*/	101	*/
102	if (sl == &printf_lock)	102	if (sl == &printf_lock)
103	continue;	103	continue;
104	#ifdef CONFIG_FB	104	#ifdef CONFIG_FB
105	if (sl == &fb_lock)	105	if (sl == &fb_lock)
106	continue;	106	continue;
107	#endif	107	#endif
108	if (i++ > DEADLOCK_THRESHOLD) {	108	if (i++ > DEADLOCK_THRESHOLD) {
109	printf("cpu%d: looping on spinlock %.*p:%s, "	109	printf("cpu%u: looping on spinlock %" PRIp ":%s, caller=%" PRIp,
110	"caller=%.p", CPU->id, sizeof(uintptr_t) 2, sl,	-
111	sl->name, sizeof(uintptr_t) * 2, CALLER);	110	CPU->id, sl, sl->name, CALLER);
112	symbol = get_symtab_entry(CALLER);	111	symbol = get_symtab_entry(CALLER);
113	if (symbol)	112	if (symbol)
114	printf("(%s)", symbol);	113	printf("(%s)", symbol);
115	printf("\n");	114	printf("\n");
116	i = 0;	115	i = 0;
117	deadlock_reported = true;	116	deadlock_reported = true;
118	}	117	}
119	}	118	}
120		119
121	if (deadlock_reported)	120	if (deadlock_reported)
122	printf("cpu%d: not deadlocked\n", CPU->id);	121	printf("cpu%u: not deadlocked\n", CPU->id);
123		122
124	/*	123	/*
125	* Prevent critical section code from bleeding out this way up.	124	* Prevent critical section code from bleeding out this way up.
126	*/	125	*/
127	CS_ENTER_BARRIER();	126	CS_ENTER_BARRIER();
128	}	127	}
129	#endif	128	#endif
130		129
131	/** Lock spinlock conditionally	130	/** Lock spinlock conditionally
132	*	131	*
133	* Lock spinlock conditionally.	132	* Lock spinlock conditionally.
134	* If the spinlock is not available at the moment,	133	* If the spinlock is not available at the moment,
135	* signal failure.	134	* signal failure.
136	*	135	*
137	* @param sl Pointer to spinlock_t structure.	136	* @param sl Pointer to spinlock_t structure.
138	*	137	*
139	* @return Zero on failure, non-zero otherwise.	138	* @return Zero on failure, non-zero otherwise.
140	*/	139	*/
141	int spinlock_trylock(spinlock_t *sl)	140	int spinlock_trylock(spinlock_t *sl)
142	{	141	{
143	int rc;	142	int rc;
144		143
145	preemption_disable();	144	preemption_disable();
146	rc = !test_and_set(&sl->val);	145	rc = !test_and_set(&sl->val);
147		146
148	/*	147	/*
149	* Prevent critical section code from bleeding out this way up.	148	* Prevent critical section code from bleeding out this way up.
150	*/	149	*/
151	CS_ENTER_BARRIER();	150	CS_ENTER_BARRIER();
152		151
153	if (!rc)	152	if (!rc)
154	preemption_enable();	153	preemption_enable();
155		154
156	return rc;	155	return rc;
157	}	156	}
158		157
159	#endif	158	#endif
160		159
161	/** @}	160	/** @}
162	*/	161	*/
163		162

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(root)/branches/dd/kernel/generic/src/synch/spinlock.c – Rev 3022 → 4055