WebSVN – HelenOS-historic – Diff – /kernel/trunk/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
#define DEADLOCK_THRESHOLD  100000000
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 printflock 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
         * printflock and fb_lock.
         *
         * Possible deadlocks on both printflock and fb_lock
         * are therefore not reported as they would cause an
         * infinite recursion.
         */
        if (sl == &printflock)
            continue;
#ifdef CONFIG_FB
        if (sl == &fb_lock)
            continue;
#endif
        if (i++ > DEADLOCK_THRESHOLD) {
            printf("cpu%d: looping on spinlock %.*p:%s, caller=%.*p",
                   CPU->id, sizeof(__address) * 2, sl, sl->name, sizeof(__address) * 2, CALLER);
            symbol = get_symtab_entry(CALLER);
            if (symbol)
                printf("(%s)", symbol);
            printf("\n");
            i = 0;
            deadlock_reported = true;
        }
    }
 
    if (deadlock_reported)
        printf("cpu%d: 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 1667	Rev 1702
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
-		30	* @{
-		31	*/
-		32
29	/**	33	/**
30	* @file spinlock.c	34	* @file
31	* @brief Spinlocks.	35	* @brief Spinlocks.
32	*/	36	*/
33		37
34	#include <synch/spinlock.h>	38	#include <synch/spinlock.h>
35	#include <atomic.h>	39	#include <atomic.h>
36	#include <arch/barrier.h>	40	#include <arch/barrier.h>
37	#include <arch.h>	41	#include <arch.h>
38	#include <preemption.h>	42	#include <preemption.h>
39	#include <print.h>	43	#include <print.h>
40	#include <debug.h>	44	#include <debug.h>
41	#include <symtab.h>	45	#include <symtab.h>
42		46
43	#ifdef CONFIG_FB	47	#ifdef CONFIG_FB
44	#include <genarch/fb/fb.h>	48	#include <genarch/fb/fb.h>
45	#endif	49	#endif
46		50
47	#ifdef CONFIG_SMP	51	#ifdef CONFIG_SMP
48		52
49	/** Initialize spinlock	53	/** Initialize spinlock
50	*	54	*
51	* Initialize spinlock.	55	* Initialize spinlock.
52	*	56	*
53	* @param sl Pointer to spinlock_t structure.	57	* @param sl Pointer to spinlock_t structure.
54	*/	58	*/
55	void spinlock_initialize(spinlock_t sl, char name)	59	void spinlock_initialize(spinlock_t sl, char name)
56	{	60	{
57	atomic_set(&sl->val, 0);	61	atomic_set(&sl->val, 0);
58	#ifdef CONFIG_DEBUG_SPINLOCK	62	#ifdef CONFIG_DEBUG_SPINLOCK
59	sl->name = name;	63	sl->name = name;
60	#endif	64	#endif
61	}	65	}
62		66
63	/** Lock spinlock	67	/** Lock spinlock
64	*	68	*
65	* Lock spinlock.	69	* Lock spinlock.
66	* This version has limitted ability to report	70	* This version has limitted ability to report
67	* possible occurence of deadlock.	71	* possible occurence of deadlock.
68	*	72	*
69	* @param sl Pointer to spinlock_t structure.	73	* @param sl Pointer to spinlock_t structure.
70	*/	74	*/
71	#ifdef CONFIG_DEBUG_SPINLOCK	75	#ifdef CONFIG_DEBUG_SPINLOCK
72	#define DEADLOCK_THRESHOLD 100000000	76	#define DEADLOCK_THRESHOLD 100000000
73	void spinlock_lock_debug(spinlock_t *sl)	77	void spinlock_lock_debug(spinlock_t *sl)
74	{	78	{
75	count_t i = 0;	79	count_t i = 0;
76	char *symbol;	80	char *symbol;
77	bool deadlock_reported = false;	81	bool deadlock_reported = false;
78		82
79	preemption_disable();	83	preemption_disable();
80	while (test_and_set(&sl->val)) {	84	while (test_and_set(&sl->val)) {
81		85
82	/*	86	/*
83	* We need to be careful about printflock and fb_lock.	87	* We need to be careful about printflock and fb_lock.
84	* Both of them are used to report deadlocks via	88	* Both of them are used to report deadlocks via
85	* printf() and fb_putchar().	89	* printf() and fb_putchar().
86	*	90	*
87	* We trust our code that there is no possible deadlock	91	* We trust our code that there is no possible deadlock
88	* caused by these two locks (except when an exception	92	* caused by these two locks (except when an exception
89	* is triggered for instance by printf() or fb_putchar()).	93	* is triggered for instance by printf() or fb_putchar()).
90	* However, we encountered false positives caused by very	94	* However, we encountered false positives caused by very
91	* slow VESA framebuffer interaction (especially when	95	* slow VESA framebuffer interaction (especially when
92	* run in a simulator) that caused problems with both	96	* run in a simulator) that caused problems with both
93	* printflock and fb_lock.	97	* printflock and fb_lock.
94	*	98	*
95	* Possible deadlocks on both printflock and fb_lock	99	* Possible deadlocks on both printflock and fb_lock
96	* are therefore not reported as they would cause an	100	* are therefore not reported as they would cause an
97	* infinite recursion.	101	* infinite recursion.
98	*/	102	*/
99	if (sl == &printflock)	103	if (sl == &printflock)
100	continue;	104	continue;
101	#ifdef CONFIG_FB	105	#ifdef CONFIG_FB
102	if (sl == &fb_lock)	106	if (sl == &fb_lock)
103	continue;	107	continue;
104	#endif	108	#endif
105	if (i++ > DEADLOCK_THRESHOLD) {	109	if (i++ > DEADLOCK_THRESHOLD) {
106	printf("cpu%d: looping on spinlock %.p:%s, caller=%.p",	110	printf("cpu%d: looping on spinlock %.p:%s, caller=%.p",
107	CPU->id, sizeof(__address) * 2, sl, sl->name, sizeof(__address) * 2, CALLER);	111	CPU->id, sizeof(__address) * 2, sl, sl->name, sizeof(__address) * 2, CALLER);
108	symbol = get_symtab_entry(CALLER);	112	symbol = get_symtab_entry(CALLER);
109	if (symbol)	113	if (symbol)
110	printf("(%s)", symbol);	114	printf("(%s)", symbol);
111	printf("\n");	115	printf("\n");
112	i = 0;	116	i = 0;
113	deadlock_reported = true;	117	deadlock_reported = true;
114	}	118	}
115	}	119	}
116		120
117	if (deadlock_reported)	121	if (deadlock_reported)
118	printf("cpu%d: not deadlocked\n", CPU->id);	122	printf("cpu%d: not deadlocked\n", CPU->id);
119		123
120	/*	124	/*
121	* Prevent critical section code from bleeding out this way up.	125	* Prevent critical section code from bleeding out this way up.
122	*/	126	*/
123	CS_ENTER_BARRIER();	127	CS_ENTER_BARRIER();
124	}	128	}
125	#endif	129	#endif
126		130
127	/** Lock spinlock conditionally	131	/** Lock spinlock conditionally
128	*	132	*
129	* Lock spinlock conditionally.	133	* Lock spinlock conditionally.
130	* If the spinlock is not available at the moment,	134	* If the spinlock is not available at the moment,
131	* signal failure.	135	* signal failure.
132	*	136	*
133	* @param sl Pointer to spinlock_t structure.	137	* @param sl Pointer to spinlock_t structure.
134	*	138	*
135	* @return Zero on failure, non-zero otherwise.	139	* @return Zero on failure, non-zero otherwise.
136	*/	140	*/
137	int spinlock_trylock(spinlock_t *sl)	141	int spinlock_trylock(spinlock_t *sl)
138	{	142	{
139	int rc;	143	int rc;
140		144
141	preemption_disable();	145	preemption_disable();
142	rc = !test_and_set(&sl->val);	146	rc = !test_and_set(&sl->val);
143		147
144	/*	148	/*
145	* Prevent critical section code from bleeding out this way up.	149	* Prevent critical section code from bleeding out this way up.
146	*/	150	*/
147	CS_ENTER_BARRIER();	151	CS_ENTER_BARRIER();
148		152
149	if (!rc)	153	if (!rc)
150	preemption_enable();	154	preemption_enable();
151		155
152	return rc;	156	return rc;
153	}	157	}
154		158
155	#endif	159	#endif
-		160
-		161	/** @}
-		162	*/
-		163
156		164

Subversion Repositories HelenOS-historic

(root)/kernel/trunk/generic/src/synch/spinlock.c – Rev 1667 → 1702