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.
 */
 
/**
 * @file    spinlock.c
 * @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 1323	Rev 1667
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	/**	29	/**
30	* @file spinlock.c	30	* @file spinlock.c
31	* @brief Spinlocks.	31	* @brief Spinlocks.
32	*/	32	*/
33		33
34	#include <synch/spinlock.h>	34	#include <synch/spinlock.h>
35	#include <atomic.h>	35	#include <atomic.h>
36	#include <arch/barrier.h>	36	#include <arch/barrier.h>
37	#include <arch.h>	37	#include <arch.h>
38	#include <preemption.h>	38	#include <preemption.h>
39	#include <print.h>	39	#include <print.h>
40	#include <debug.h>	40	#include <debug.h>
41	#include <symtab.h>	41	#include <symtab.h>
42		42
43	#ifdef CONFIG_FB	43	#ifdef CONFIG_FB
44	#include <genarch/fb/fb.h>	44	#include <genarch/fb/fb.h>
45	#endif	45	#endif
46		46
47	#ifdef CONFIG_SMP	47	#ifdef CONFIG_SMP
48		48
49	/** Initialize spinlock	49	/** Initialize spinlock
50	*	50	*
51	* Initialize spinlock.	51	* Initialize spinlock.
52	*	52	*
53	* @param sl Pointer to spinlock_t structure.	53	* @param sl Pointer to spinlock_t structure.
54	*/	54	*/
55	void spinlock_initialize(spinlock_t sl, char name)	55	void spinlock_initialize(spinlock_t sl, char name)
56	{	56	{
57	atomic_set(&sl->val, 0);	57	atomic_set(&sl->val, 0);
58	#ifdef CONFIG_DEBUG_SPINLOCK	58	#ifdef CONFIG_DEBUG_SPINLOCK
59	sl->name = name;	59	sl->name = name;
60	#endif	60	#endif
61	}	61	}
62		62
63	/** Lock spinlock	63	/** Lock spinlock
64	*	64	*
65	* Lock spinlock.	65	* Lock spinlock.
66	* This version has limitted ability to report	66	* This version has limitted ability to report
67	* possible occurence of deadlock.	67	* possible occurence of deadlock.
68	*	68	*
69	* @param sl Pointer to spinlock_t structure.	69	* @param sl Pointer to spinlock_t structure.
70	*/	70	*/
71	#ifdef CONFIG_DEBUG_SPINLOCK	71	#ifdef CONFIG_DEBUG_SPINLOCK
-		72	#define DEADLOCK_THRESHOLD 100000000
72	void spinlock_lock_debug(spinlock_t *sl)	73	void spinlock_lock_debug(spinlock_t *sl)
73	{	74	{
74	count_t i = 0;	75	count_t i = 0;
75	char *symbol;	76	char *symbol;
76	bool deadlock_reported = false;	77	bool deadlock_reported = false;
77		78
78	preemption_disable();	79	preemption_disable();
79	while (test_and_set(&sl->val)) {	80	while (test_and_set(&sl->val)) {
80		81
81	/*	82	/*
82	* We need to be careful about printflock and fb_lock.	83	* We need to be careful about printflock and fb_lock.
83	* Both of them are used to report deadlocks via	84	* Both of them are used to report deadlocks via
84	* printf() and fb_putchar().	85	* printf() and fb_putchar().
85	*	86	*
86	* We trust our code that there is no possible deadlock	87	* We trust our code that there is no possible deadlock
87	* caused by these two locks (except when an exception	88	* caused by these two locks (except when an exception
88	* is triggered for instance by printf() or fb_putchar()).	89	* is triggered for instance by printf() or fb_putchar()).
89	* However, we encountered false positives caused by very	90	* However, we encountered false positives caused by very
90	* slow VESA framebuffer interaction (especially when	91	* slow VESA framebuffer interaction (especially when
91	* run in a simulator) that caused problems with both	92	* run in a simulator) that caused problems with both
92	* printflock and fb_lock.	93	* printflock and fb_lock.
93	*	94	*
94	* Possible deadlocks on both printflock and fb_lock	95	* Possible deadlocks on both printflock and fb_lock
95	* are therefore not reported as they would cause an	96	* are therefore not reported as they would cause an
96	* infinite recursion.	97	* infinite recursion.
97	*/	98	*/
98	if (sl == &printflock)	99	if (sl == &printflock)
99	continue;	100	continue;
100	#ifdef CONFIG_FB	101	#ifdef CONFIG_FB
101	if (sl == &fb_lock)	102	if (sl == &fb_lock)
102	continue;	103	continue;
103	#endif	104	#endif
104	if (i++ > 10000000) {	105	if (i++ > DEADLOCK_THRESHOLD) {
105	printf("cpu%d: looping on spinlock %.p:%s, caller=%.p",	106	printf("cpu%d: looping on spinlock %.p:%s, caller=%.p",
106	CPU->id, sizeof(__address) * 2, sl, sl->name, sizeof(__address) * 2, CALLER);	107	CPU->id, sizeof(__address) * 2, sl, sl->name, sizeof(__address) * 2, CALLER);
107	symbol = get_symtab_entry(CALLER);	108	symbol = get_symtab_entry(CALLER);
108	if (symbol)	109	if (symbol)
109	printf("(%s)", symbol);	110	printf("(%s)", symbol);
110	printf("\n");	111	printf("\n");
111	i = 0;	112	i = 0;
112	deadlock_reported = true;	113	deadlock_reported = true;
113	}	114	}
114	}	115	}
115		116
116	if (deadlock_reported)	117	if (deadlock_reported)
117	printf("cpu%d: not deadlocked\n", CPU->id);	118	printf("cpu%d: not deadlocked\n", CPU->id);
118		119
119	/*	120	/*
120	* Prevent critical section code from bleeding out this way up.	121	* Prevent critical section code from bleeding out this way up.
121	*/	122	*/
122	CS_ENTER_BARRIER();	123	CS_ENTER_BARRIER();
123	}	124	}
124	#endif	125	#endif
125		126
126	/** Lock spinlock conditionally	127	/** Lock spinlock conditionally
127	*	128	*
128	* Lock spinlock conditionally.	129	* Lock spinlock conditionally.
129	* If the spinlock is not available at the moment,	130	* If the spinlock is not available at the moment,
130	* signal failure.	131	* signal failure.
131	*	132	*
132	* @param sl Pointer to spinlock_t structure.	133	* @param sl Pointer to spinlock_t structure.
133	*	134	*
134	* @return Zero on failure, non-zero otherwise.	135	* @return Zero on failure, non-zero otherwise.
135	*/	136	*/
136	int spinlock_trylock(spinlock_t *sl)	137	int spinlock_trylock(spinlock_t *sl)
137	{	138	{
138	int rc;	139	int rc;
139		140
140	preemption_disable();	141	preemption_disable();
141	rc = !test_and_set(&sl->val);	142	rc = !test_and_set(&sl->val);
142		143
143	/*	144	/*
144	* Prevent critical section code from bleeding out this way up.	145	* Prevent critical section code from bleeding out this way up.
145	*/	146	*/
146	CS_ENTER_BARRIER();	147	CS_ENTER_BARRIER();
147		148
148	if (!rc)	149	if (!rc)
149	preemption_enable();	150	preemption_enable();
150		151
151	return rc;	152	return rc;
152	}	153	}
153		154
154	#endif	155	#endif
155		156

Subversion Repositories HelenOS-historic

(root)/kernel/trunk/generic/src/synch/spinlock.c – Rev 1323 → 1667