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