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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 | size_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 |