1
2 /* FIXME: this is basically a bad test as it is scheduling-
3 sensitive. Sometimes the output is:
4
5 child: new value 6
6 child: new value 10
7 done, x = 10
8
9 and sometimes
10
11 child: new value 10
12 done, x = 10
13 */
14
15 #include <pthread.h>
16 #include <stdio.h>
17 #include <stdlib.h>
18 #include <unistd.h>
19
20 /* Simple test program, no race. Parent writes atomically to a counter
21 whilst child reads it. When counter reaches a prearranged value,
22 child joins back to parent. Parent (writer) uses hardware bus lock;
23 child is only reading and so does not need to use a bus lock. */
24
25 #undef PLAT_x86_darwin
26 #undef PLAT_amd64_darwin
27 #undef PLAT_x86_linux
28 #undef PLAT_amd64_linux
29 #undef PLAT_ppc32_linux
30 #undef PLAT_ppc64_linux
31 #undef PLAT_arm_linux
32 #undef PLAT_arm64_linux
33 #undef PLAT_s390x_linux
34 #undef PLAT_mips32_linux
35 #undef PLAT_mips64_linux
36 #undef PLAT_tilegx_linux
37
38 #if defined(__APPLE__) && defined(__i386__)
39 # define PLAT_x86_darwin 1
40 #elif defined(__APPLE__) && defined(__x86_64__)
41 # define PLAT_amd64_darwin 1
42 #elif defined(__linux__) && defined(__i386__)
43 # define PLAT_x86_linux 1
44 #elif defined(__linux__) && defined(__x86_64__)
45 # define PLAT_amd64_linux 1
46 #elif defined(__linux__) && defined(__powerpc__) && !defined(__powerpc64__)
47 # define PLAT_ppc32_linux 1
48 #elif defined(__linux__) && defined(__powerpc__) && defined(__powerpc64__)
49 # define PLAT_ppc64_linux 1
50 #elif defined(__linux__) && defined(__arm__) && !defined(__aarch64__)
51 # define PLAT_arm_linux 1
52 #elif defined(__linux__) && defined(__aarch64__) && !defined(__arm__)
53 # define PLAT_arm64_linux 1
54 #elif defined(__linux__) && defined(__s390x__)
55 # define PLAT_s390x_linux 1
56 #elif defined(__linux__) && defined(__mips__)
57 #if (__mips==64)
58 # define PLAT_mips64_linux 1
59 #else
60 # define PLAT_mips32_linux 1
61 #endif
62 #elif defined(__linux__) && defined(__tilegx__)
63 # define PLAT_tilegx_linux 1
64 #endif
65
66
67 #if defined(PLAT_amd64_linux) || defined(PLAT_x86_linux) \
68 || defined(PLAT_amd64_darwin) || defined(PLAT_x86_darwin)
69 # define INC(_lval,_lqual) \
70 __asm__ __volatile__ ( \
71 "lock ; incl (%0)" : /*out*/ : /*in*/"r"(&(_lval)) : "memory", "cc" )
72 #elif defined(PLAT_ppc32_linux) || defined(PLAT_ppc64_linux)
73 # define INC(_lval,_lqual) \
74 __asm__ __volatile__( \
75 "1:\n" \
76 " lwarx 15,0,%0\n" \
77 " addi 15,15,1\n" \
78 " stwcx. 15,0,%0\n" \
79 " bne- 1b\n" \
80 : /*out*/ : /*in*/ "b"(&(_lval)) \
81 : /*trash*/ "r15", "cr0", "memory" \
82 )
83 #elif defined(PLAT_arm_linux)
84 # define INC(_lval,_lqual) \
85 __asm__ __volatile__( \
86 "1:\n" \
87 " ldrex r8, [%0, #0]\n" \
88 " add r8, r8, #1\n" \
89 " strex r9, r8, [%0, #0]\n" \
90 " cmp r9, #0\n" \
91 " bne 1b\n" \
92 : /*out*/ : /*in*/ "r"(&(_lval)) \
93 : /*trash*/ "r8", "r9", "cc", "memory" \
94 );
95 #elif defined(PLAT_arm64_linux)
96 # define INC(_lval,_lqual) \
97 __asm__ __volatile__( \
98 "1:\n" \
99 " ldxr w8, [%0, #0]\n" \
100 " add w8, w8, #1\n" \
101 " stxr w9, w8, [%0, #0]\n" \
102 " cmp w9, #0\n" \
103 " bne 1b\n" \
104 : /*out*/ : /*in*/ "r"(&(_lval)) \
105 : /*trash*/ "x8", "x9", "cc", "memory" \
106 );
107 #elif defined(PLAT_s390x_linux)
108 # define INC(_lval,_lqual) \
109 __asm__ __volatile__( \
110 "1: l 0,%0\n" \
111 " lr 1,0\n" \
112 " ahi 1,1\n" \
113 " cs 0,1,%0\n" \
114 " jl 1b\n" \
115 : "+m" (_lval) :: "cc", "0","1" \
116 )
117 #elif defined(PLAT_mips32_linux) || defined(PLAT_mips64_linux)
118 # define INC(_lval,_lqual) \
119 __asm__ __volatile__ ( \
120 "L1xyzzy1" _lqual":\n" \
121 " move $t0, %0\n" \
122 " ll $t1, 0($t0)\n" \
123 " addi $t1, $t1, 1\n" \
124 " sc $t1, 0($t0)\n" \
125 " beqz $t1, L1xyzzy1" _lqual \
126 : /*out*/ : /*in*/ "r"(&(_lval)) \
127 : /*trash*/ "t0", "t1", "memory" \
128 )
129 #elif defined(PLAT_tilegx_linux)
130 # define INC(_lval,_lqual) \
131 if (sizeof(_lval) == 4) \
132 __insn_fetchadd(&(_lval), 1); \
133 else if(sizeof(_lval) == 8) \
134 __insn_fetchadd(&(_lval), 1)
135 #else
136 # error "Fix Me for this platform"
137 #endif
138
139
140
141 #define LIMIT 10
142
143 volatile int x = 0;
144
child_fn(void * arg)145 void* child_fn ( void* arg )
146 {
147 int q = 0;
148 int oldx = 0;
149 struct timespec ts = { 0, 1000 * 1000 };
150
151 while (1) {
152 q = (x >= LIMIT);
153 if (x != oldx) {
154 oldx = x;
155 printf("child: new value %d\n", oldx);
156 fflush(stdout);
157 }
158 if (q) break;
159 nanosleep(&ts, 0);
160 }
161 return NULL;
162 }
163
main(void)164 int main ( void )
165 {
166 pthread_t child;
167 int i;
168
169 if (pthread_create(&child, NULL, child_fn, NULL)) {
170 perror("pthread_create");
171 exit(1);
172 }
173
174 for (i = 0; i < LIMIT; i++) {
175 INC(x, "main");
176 if (i == 5) sleep(1); /* make sure child doesn't starve */
177 }
178
179 if (pthread_join(child, NULL)) {
180 perror("pthread join");
181 exit(1);
182 }
183
184 printf("done, x = %d\n", x);
185
186 return 0;
187 }
188