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; 116 117 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 } 135 136 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
