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_s390x_linux
33 #undef PLAT_mips32_linux
34
35 #if defined(__APPLE__) && defined(__i386__)
36 # define PLAT_x86_darwin 1
37 #elif defined(__APPLE__) && defined(__x86_64__)
38 # define PLAT_amd64_darwin 1
39 #elif defined(__linux__) && defined(__i386__)
40 # define PLAT_x86_linux 1
41 #elif defined(__linux__) && defined(__x86_64__)
42 # define PLAT_amd64_linux 1
43 #elif defined(__linux__) && defined(__powerpc__) && !defined(__powerpc64__)
44 # define PLAT_ppc32_linux 1
45 #elif defined(__linux__) && defined(__powerpc__) && defined(__powerpc64__)
46 # define PLAT_ppc64_linux 1
47 #elif defined(__linux__) && defined(__arm__)
48 # define PLAT_arm_linux 1
49 #elif defined(__linux__) && defined(__s390x__)
50 # define PLAT_s390x_linux 1
51 #elif defined(__linux__) && defined(__mips__)
52 # define PLAT_mips32_linux 1
53 #endif
54
55
56 #if defined(PLAT_amd64_linux) || defined(PLAT_x86_linux) \
57 || defined(PLAT_amd64_darwin) || defined(PLAT_x86_darwin)
58 # define INC(_lval,_lqual) \
59 __asm__ __volatile__ ( \
60 "lock ; incl (%0)" : /*out*/ : /*in*/"r"(&(_lval)) : "memory", "cc" )
61 #elif defined(PLAT_ppc32_linux) || defined(PLAT_ppc64_linux)
62 # define INC(_lval,_lqual) \
63 __asm__ __volatile__( \
64 "1:\n" \
65 " lwarx 15,0,%0\n" \
66 " addi 15,15,1\n" \
67 " stwcx. 15,0,%0\n" \
68 " bne- 1b\n" \
69 : /*out*/ : /*in*/ "b"(&(_lval)) \
70 : /*trash*/ "r15", "cr0", "memory" \
71 )
72 #elif defined(PLAT_arm_linux)
73 # define INC(_lval,_lqual) \
74 __asm__ __volatile__( \
75 "1:\n" \
76 " ldrex r8, [%0, #0]\n" \
77 " add r8, r8, #1\n" \
78 " strex r9, r8, [%0, #0]\n" \
79 " cmp r9, #0\n" \
80 " bne 1b\n" \
81 : /*out*/ : /*in*/ "r"(&(_lval)) \
82 : /*trash*/ "r8", "r9", "cc", "memory" \
83 );
84 #elif defined(PLAT_s390x_linux)
85 # define INC(_lval,_lqual) \
86 __asm__ __volatile__( \
87 "1: l 0,%0\n" \
88 " lr 1,0\n" \
89 " ahi 1,1\n" \
90 " cs 0,1,%0\n" \
91 " jl 1b\n" \
92 : "+m" (_lval) :: "cc", "0","1" \
93 )
94 #elif defined(PLAT_mips32_linux)
95 # define INC(_lval,_lqual) \
96 __asm__ __volatile__ ( \
97 "L1xyzzy1" _lqual":\n" \
98 " move $8, %0\n" \
99 " ll $9, 0($t0)\n" \
100 " addi $9, $9, 1\n" \
101 " sc $9, 0($t0)\n" \
102 " li $10, 1\n" \
103 " bne $9, $10, L1xyzzy1" _lqual \
104 : /*out*/ : /*in*/ "r"(&(_lval)) \
105 : /*trash*/ "$8", "$9", "$10", "cc", "memory" \
106 )
107 #else
108 # error "Fix Me for this platform"
109 #endif
110
111
112
113 #define LIMIT 10
114
115 volatile int x = 0;
116
child_fn(void * arg)117 void* child_fn ( void* arg )
118 {
119 int q = 0;
120 int oldx = 0;
121 struct timespec ts = { 0, 1000 * 1000 };
122
123 while (1) {
124 q = (x >= LIMIT);
125 if (x != oldx) {
126 oldx = x;
127 printf("child: new value %d\n", oldx);
128 fflush(stdout);
129 }
130 if (q) break;
131 nanosleep(&ts, 0);
132 }
133 return NULL;
134 }
135
main(void)136 int main ( void )
137 {
138 pthread_t child;
139 int i;
140
141 if (pthread_create(&child, NULL, child_fn, NULL)) {
142 perror("pthread_create");
143 exit(1);
144 }
145
146 for (i = 0; i < LIMIT; i++) {
147 INC(x, "main");
148 if (i == 5) sleep(1); /* make sure child doesn't starve */
149 }
150
151 if (pthread_join(child, NULL)) {
152 perror("pthread join");
153 exit(1);
154 }
155
156 printf("done, x = %d\n", x);
157
158 return 0;
159 }
160