src/compiler-rt/test/msan/fork.cc

   1 // Test that chained origins are fork-safe.
   2 // Run a number of threads that create new chained origins, then fork
   3 // and verify that origin reads do not deadlock in the child process.
   4
   5 // RUN: %clangxx_msan -std=c++11 -fsanitize-memory-track-origins=2 -g -O3 %s -o %t
   6 // RUN: MSAN_OPTIONS=store_context_size=1000,origin_history_size=0,origin_history_per_stack_limit=0 %run %t |& FileCheck %s
   7
   8 // Fun fact: if test output is redirected to a file (as opposed to
   9 // being piped directly to FileCheck), we may lose some "done"s due to
  10 // a kernel bug:
  11 // https://lkml.org/lkml/2014/2/17/324
  12
  13
  14 #include <pthread.h>
  15 #include <unistd.h>
  16 #include <stdio.h>
  17 #include <stdlib.h>
  18 #include <sys/types.h>
  19 #include <sys/wait.h>
  20 #include <sys/time.h>
  21 #include <signal.h>
  22 #include <errno.h>
  23
  24 #include <sanitizer/msan_interface.h>
  25
  26 int done;
  27
  28 void copy_uninit_thread2() {
  29   volatile int x;
  30   volatile int v;
  31   while (true) {
  32     v = x;
  33     x = v;
  34     if (__atomic_load_n(&done, __ATOMIC_RELAXED))
  35       return;
  36   }
  37 }
  38
  39 void copy_uninit_thread1(int level) {
  40   if (!level)
  41     copy_uninit_thread2();
  42   else
  43     copy_uninit_thread1(level - 1);
  44 }
  45
  46 void *copy_uninit_thread(void *id) {
  47   copy_uninit_thread1((long)id);
  48   return 0;
  49 }
  50
  51 // Run through stackdepot in the child process.
  52 // If any of the hash table cells are locked, this may deadlock.
  53 void child() {
  54   volatile int x;
  55   volatile int v;
  56   for (int i = 0; i < 10000; ++i) {
  57     v = x;
  58     x = v;
  59   }
  60   write(2, "done\n", 5);
  61 }
  62
  63 void test() {
  64   const int kThreads = 10;
  65   pthread_t t[kThreads];
  66   for (int i = 0; i < kThreads; ++i)
  67     pthread_create(&t[i], NULL, copy_uninit_thread, (void*)(long)i);
  68   usleep(100000);
  69   pid_t pid = fork();
  70   if (pid) {
  71     // parent
  72     __atomic_store_n(&done, 1, __ATOMIC_RELAXED);
  73     pid_t p;
  74     while ((p = wait(NULL)) == -1) {  }
  75   } else {
  76     // child
  77     child();
  78   }
  79 }
  80
  81 int main() {
  82   const int kChildren = 20;
  83   for (int i = 0; i < kChildren; ++i) {
  84     pid_t pid = fork();
  85     if (pid) {
  86       // parent
  87     } else {
  88       test();
  89       exit(0);
  90     }
  91   }
  92
  93   for (int i = 0; i < kChildren; ++i) {
  94     pid_t p;
  95     while ((p = wait(NULL)) == -1) {  }
  96   }
  97
  98   return 0;
  99 }
 100
 101 // Expect 20 (== kChildren) "done" messages.
 102 // CHECK: done
 103 // CHECK: done
 104 // CHECK: done
 105 // CHECK: done
 106 // CHECK: done
 107 // CHECK: done
 108 // CHECK: done
 109 // CHECK: done
 110 // CHECK: done
 111 // CHECK: done
 112 // CHECK: done
 113 // CHECK: done
 114 // CHECK: done
 115 // CHECK: done
 116 // CHECK: done
 117 // CHECK: done
 118 // CHECK: done
 119 // CHECK: done
 120 // CHECK: done
 121 // CHECK: done