WebSVN – HelenOS – Diff – /trunk/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>
 
#ifdef CONFIG_SYMTAB
#include <symtab.h>
#endif
 
#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;
 
    bool deadlock_reported = false;
#ifdef CONFIG_SYMTAB
    char *symbol;
#endif
 
    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);
#ifdef CONFIG_SYMTAB
            symbol = get_symtab_entry(CALLER);
            if (symbol)
                printf("(%s)", symbol);
#endif
            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 3059	Rev 4132
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
-		46	#ifdef CONFIG_SYMTAB
45	#include <symtab.h>	47	#include <symtab.h>
-		48	#endif
46		49
47	#ifdef CONFIG_FB	50	#ifdef CONFIG_FB
48	#include <genarch/fb/fb.h>	51	#include <genarch/fb/fb.h>
49	#endif	52	#endif
50		53
51	#ifdef CONFIG_SMP	54	#ifdef CONFIG_SMP
52		55
53	/** Initialize spinlock	56	/** Initialize spinlock
54	*	57	*
55	* Initialize spinlock.	58	* Initialize spinlock.
56	*	59	*
57	* @param sl Pointer to spinlock_t structure.	60	* @param sl Pointer to spinlock_t structure.
58	*/	61	*/
59	void spinlock_initialize(spinlock_t sl, char name)	62	void spinlock_initialize(spinlock_t sl, char name)
60	{	63	{
61	atomic_set(&sl->val, 0);	64	atomic_set(&sl->val, 0);
62	#ifdef CONFIG_DEBUG_SPINLOCK	65	#ifdef CONFIG_DEBUG_SPINLOCK
63	sl->name = name;	66	sl->name = name;
64	#endif	67	#endif
65	}	68	}
66		69
67	/** Lock spinlock	70	/** Lock spinlock
68	*	71	*
69	* Lock spinlock.	72	* Lock spinlock.
70	* This version has limitted ability to report	73	* This version has limitted ability to report
71	* possible occurence of deadlock.	74	* possible occurence of deadlock.
72	*	75	*
73	* @param sl Pointer to spinlock_t structure.	76	* @param sl Pointer to spinlock_t structure.
74	*/	77	*/
75	#ifdef CONFIG_DEBUG_SPINLOCK	78	#ifdef CONFIG_DEBUG_SPINLOCK
76	void spinlock_lock_debug(spinlock_t *sl)	79	void spinlock_lock_debug(spinlock_t *sl)
77	{	80	{
78	count_t i = 0;	81	count_t i = 0;
79	char *symbol;	-
80	bool deadlock_reported = false;	82	bool deadlock_reported = false;
-		83	#ifdef CONFIG_SYMTAB
-		84	char *symbol;
-		85	#endif
81		86
82	preemption_disable();	87	preemption_disable();
83	while (test_and_set(&sl->val)) {	88	while (test_and_set(&sl->val)) {
84		89
85	/*	90	/*
86	* We need to be careful about printf_lock and fb_lock.	91	* We need to be careful about printf_lock and fb_lock.
87	* Both of them are used to report deadlocks via	92	* Both of them are used to report deadlocks via
88	* printf() and fb_putchar().	93	* printf() and fb_putchar().
89	*	94	*
90	* We trust our code that there is no possible deadlock	95	* We trust our code that there is no possible deadlock
91	* caused by these two locks (except when an exception	96	* caused by these two locks (except when an exception
92	* is triggered for instance by printf() or fb_putchar()).	97	* is triggered for instance by printf() or fb_putchar()).
93	* However, we encountered false positives caused by very	98	* However, we encountered false positives caused by very
94	* slow VESA framebuffer interaction (especially when	99	* slow VESA framebuffer interaction (especially when
95	* run in a simulator) that caused problems with both	100	* run in a simulator) that caused problems with both
96	* printf_lock and fb_lock.	101	* printf_lock and fb_lock.
97	*	102	*
98	* Possible deadlocks on both printf_lock and fb_lock	103	* Possible deadlocks on both printf_lock and fb_lock
99	* are therefore not reported as they would cause an	104	* are therefore not reported as they would cause an
100	* infinite recursion.	105	* infinite recursion.
101	*/	106	*/
102	if (sl == &printf_lock)	107	if (sl == &printf_lock)
103	continue;	108	continue;
104	#ifdef CONFIG_FB	109	#ifdef CONFIG_FB
105	if (sl == &fb_lock)	110	if (sl == &fb_lock)
106	continue;	111	continue;
107	#endif	112	#endif
108	if (i++ > DEADLOCK_THRESHOLD) {	113	if (i++ > DEADLOCK_THRESHOLD) {
109	printf("cpu%u: looping on spinlock %" PRIp ":%s, caller=%" PRIp,	114	printf("cpu%u: looping on spinlock %" PRIp ":%s, caller=%" PRIp,
110	CPU->id, sl, sl->name, CALLER);	115	CPU->id, sl, sl->name, CALLER);
-		116	#ifdef CONFIG_SYMTAB
111	symbol = get_symtab_entry(CALLER);	117	symbol = get_symtab_entry(CALLER);
112	if (symbol)	118	if (symbol)
113	printf("(%s)", symbol);	119	printf("(%s)", symbol);
-		120	#endif
114	printf("\n");	121	printf("\n");
115	i = 0;	122	i = 0;
116	deadlock_reported = true;	123	deadlock_reported = true;
117	}	124	}
118	}	125	}
119		126
120	if (deadlock_reported)	127	if (deadlock_reported)
121	printf("cpu%u: not deadlocked\n", CPU->id);	128	printf("cpu%u: not deadlocked\n", CPU->id);
122		129
123	/*	130	/*
124	* Prevent critical section code from bleeding out this way up.	131	* Prevent critical section code from bleeding out this way up.
125	*/	132	*/
126	CS_ENTER_BARRIER();	133	CS_ENTER_BARRIER();
127	}	134	}
128	#endif	135	#endif
129		136
130	/** Lock spinlock conditionally	137	/** Lock spinlock conditionally
131	*	138	*
132	* Lock spinlock conditionally.	139	* Lock spinlock conditionally.
133	* If the spinlock is not available at the moment,	140	* If the spinlock is not available at the moment,
134	* signal failure.	141	* signal failure.
135	*	142	*
136	* @param sl Pointer to spinlock_t structure.	143	* @param sl Pointer to spinlock_t structure.
137	*	144	*
138	* @return Zero on failure, non-zero otherwise.	145	* @return Zero on failure, non-zero otherwise.
139	*/	146	*/
140	int spinlock_trylock(spinlock_t *sl)	147	int spinlock_trylock(spinlock_t *sl)
141	{	148	{
142	int rc;	149	int rc;
143		150
144	preemption_disable();	151	preemption_disable();
145	rc = !test_and_set(&sl->val);	152	rc = !test_and_set(&sl->val);
146		153
147	/*	154	/*
148	* Prevent critical section code from bleeding out this way up.	155	* Prevent critical section code from bleeding out this way up.
149	*/	156	*/
150	CS_ENTER_BARRIER();	157	CS_ENTER_BARRIER();
151		158
152	if (!rc)	159	if (!rc)
153	preemption_enable();	160	preemption_enable();
154		161
155	return rc;	162	return rc;
156	}	163	}
157		164
158	#endif	165	#endif
159		166
160	/** @}	167	/** @}
161	*/	168	*/
162		169

Subversion Repositories HelenOS

(root)/trunk/kernel/generic/src/synch/spinlock.c @ 2472 – Rev 3059 → 4132