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 #undef PLAT_x86_solaris
38 #undef PLAT_amd64_solaris
39
40 #if defined(__APPLE__) && defined(__i386__)
41 # define PLAT_x86_darwin 1
42 #elif defined(__APPLE__) && defined(__x86_64__)
43 # define PLAT_amd64_darwin 1
44 #elif defined(__linux__) && defined(__i386__)
45 # define PLAT_x86_linux 1
46 #elif defined(__linux__) && defined(__x86_64__)
47 # define PLAT_amd64_linux 1
48 #elif defined(__linux__) && defined(__powerpc__) && !defined(__powerpc64__)
49 # define PLAT_ppc32_linux 1
50 #elif defined(__linux__) && defined(__powerpc__) && defined(__powerpc64__)
51 # define PLAT_ppc64_linux 1
52 #elif defined(__linux__) && defined(__arm__) && !defined(__aarch64__)
53 # define PLAT_arm_linux 1
54 #elif defined(__linux__) && defined(__aarch64__) && !defined(__arm__)
55 # define PLAT_arm64_linux 1
56 #elif defined(__linux__) && defined(__s390x__)
57 # define PLAT_s390x_linux 1
58 #elif defined(__linux__) && defined(__mips__)
59 #if (__mips==64)
60 # define PLAT_mips64_linux 1
61 #else
62 # define PLAT_mips32_linux 1
63 #endif
64 #elif defined(__linux__) && defined(__tilegx__)
65 # define PLAT_tilegx_linux 1
66 #elif defined(__sun__) && defined(__i386__)
67 # define PLAT_x86_solaris 1
68 #elif defined(__sun__) && defined(__x86_64__)
69 # define PLAT_amd64_solaris 1
70 #endif
71
72
73 #if defined(PLAT_amd64_linux) || defined(PLAT_x86_linux) \
74 || defined(PLAT_amd64_darwin) || defined(PLAT_x86_darwin) \
75 || defined(PLAT_amd64_solaris) || defined(PLAT_x86_solaris)
76 # define INC(_lval,_lqual) \
77 __asm__ __volatile__ ( \
78 "lock ; incl (%0)" : /*out*/ : /*in*/"r"(&(_lval)) : "memory", "cc" )
79 #elif defined(PLAT_ppc32_linux) || defined(PLAT_ppc64_linux)
80 # define INC(_lval,_lqual) \
81 __asm__ __volatile__( \
82 "1:\n" \
83 " lwarx 15,0,%0\n" \
84 " addi 15,15,1\n" \
85 " stwcx. 15,0,%0\n" \
86 " bne- 1b\n" \
87 : /*out*/ : /*in*/ "b"(&(_lval)) \
88 : /*trash*/ "r15", "cr0", "memory" \
89 )
90 #elif defined(PLAT_arm_linux)
91 # define INC(_lval,_lqual) \
92 __asm__ __volatile__( \
93 "1:\n" \
94 " ldrex r8, [%0, #0]\n" \
95 " add r8, r8, #1\n" \
96 " strex r9, r8, [%0, #0]\n" \
97 " cmp r9, #0\n" \
98 " bne 1b\n" \
99 : /*out*/ : /*in*/ "r"(&(_lval)) \
100 : /*trash*/ "r8", "r9", "cc", "memory" \
101 );
102 #elif defined(PLAT_arm64_linux)
103 # define INC(_lval,_lqual) \
104 __asm__ __volatile__( \
105 "1:\n" \
106 " ldxr w8, [%0, #0]\n" \
107 " add w8, w8, #1\n" \
108 " stxr w9, w8, [%0, #0]\n" \
109 " cmp w9, #0\n" \
110 " bne 1b\n" \
111 : /*out*/ : /*in*/ "r"(&(_lval)) \
112 : /*trash*/ "x8", "x9", "cc", "memory" \
113 );
114 #elif defined(PLAT_s390x_linux)
115 # define INC(_lval,_lqual) \
116 __asm__ __volatile__( \
117 "1: l 0,%0\n" \
118 " lr 1,0\n" \
119 " ahi 1,1\n" \
120 " cs 0,1,%0\n" \
121 " jl 1b\n" \
122 : "+m" (_lval) :: "cc", "0","1" \
123 )
124 #elif defined(PLAT_mips32_linux) || defined(PLAT_mips64_linux)
125 # define INC(_lval,_lqual) \
126 __asm__ __volatile__ ( \
127 "L1xyzzy1" _lqual":\n" \
128 " move $t0, %0\n" \
129 " ll $t1, 0($t0)\n" \
130 " addi $t1, $t1, 1\n" \
131 " sc $t1, 0($t0)\n" \
132 " beqz $t1, L1xyzzy1" _lqual \
133 : /*out*/ : /*in*/ "r"(&(_lval)) \
134 : /*trash*/ "t0", "t1", "memory" \
135 )
136 #elif defined(PLAT_tilegx_linux)
137 # define INC(_lval,_lqual) \
138 if (sizeof(_lval) == 4) \
139 __insn_fetchadd(&(_lval), 1); \
140 else if(sizeof(_lval) == 8) \
141 __insn_fetchadd(&(_lval), 1)
142 #else
143 # error "Fix Me for this platform"
144 #endif
145
146
147
148 #define LIMIT 10
149
150 volatile int x = 0;
151
child_fn(void * arg)152 void* child_fn ( void* arg )
153 {
154 int q = 0;
155 int oldx = 0;
156 struct timespec ts = { 0, 1000 * 1000 };
157
158 while (1) {
159 q = (x >= LIMIT);
160 if (x != oldx) {
161 oldx = x;
162 printf("child: new value %d\n", oldx);
163 fflush(stdout);
164 }
165 if (q) break;
166 nanosleep(&ts, 0);
167 }
168 return NULL;
169 }
170
main(void)171 int main ( void )
172 {
173 pthread_t child;
174 int i;
175
176 if (pthread_create(&child, NULL, child_fn, NULL)) {
177 perror("pthread_create");
178 exit(1);
179 }
180
181 for (i = 0; i < LIMIT; i++) {
182 INC(x, "main");
183 if (i == 5) sleep(1); /* make sure child doesn't starve */
184 }
185
186 if (pthread_join(child, NULL)) {
187 perror("pthread join");
188 exit(1);
189 }
190
191 printf("done, x = %d\n", x);
192
193 return 0;
194 }
195