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 2>&1 | 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 // Flaky on PPC64.
  14 // UNSUPPORTED: powerpc64-target-arch
  15 // UNSUPPORTED: powerpc64le-target-arch
  16
  17 #include <pthread.h>
  18 #include <unistd.h>
  19 #include <stdio.h>
  20 #include <stdlib.h>
  21 #include <sys/types.h>
  22 #include <sys/wait.h>
  23 #include <sys/time.h>
  24 #include <signal.h>
  25 #include <errno.h>
  26
  27 #include <sanitizer/msan_interface.h>
  28
  29 int done;
  30
  31 void copy_uninit_thread2() {
  32   volatile int x;
  33   volatile int v;
  34   while (true) {
  35     v = x;
  36     x = v;
  37     if (__atomic_load_n(&done, __ATOMIC_RELAXED))
  38       return;
  39   }
  40 }
  41
  42 void copy_uninit_thread1(int level) {
  43   if (!level)
  44     copy_uninit_thread2();
  45   else
  46     copy_uninit_thread1(level - 1);
  47 }
  48
  49 void *copy_uninit_thread(void *id) {
  50   copy_uninit_thread1((long)id);
  51   return 0;
  52 }
  53
  54 // Run through stackdepot in the child process.
  55 // If any of the hash table cells are locked, this may deadlock.
  56 void child() {
  57   volatile int x;
  58   volatile int v;
  59   for (int i = 0; i < 10000; ++i) {
  60     v = x;
  61     x = v;
  62   }
  63   write(2, "done\n", 5);
  64 }
  65
  66 void test() {
  67   const int kThreads = 10;
  68   pthread_t t[kThreads];
  69   for (int i = 0; i < kThreads; ++i)
  70     pthread_create(&t[i], NULL, copy_uninit_thread, (void*)(long)i);
  71   usleep(100000);
  72   pid_t pid = fork();
  73   if (pid) {
  74     // parent
  75     __atomic_store_n(&done, 1, __ATOMIC_RELAXED);
  76     pid_t p;
  77     while ((p = wait(NULL)) == -1) {  }
  78   } else {
  79     // child
  80     child();
  81   }
  82 }
  83
  84 int main() {
  85   const int kChildren = 20;
  86   for (int i = 0; i < kChildren; ++i) {
  87     pid_t pid = fork();
  88     if (pid) {
  89       // parent
  90     } else {
  91       test();
  92       exit(0);
  93     }
  94   }
  95
  96   for (int i = 0; i < kChildren; ++i) {
  97     pid_t p;
  98     while ((p = wait(NULL)) == -1) {  }
  99   }
 100
 101   return 0;
 102 }
 103
 104 // Expect 20 (== kChildren) "done" messages.
 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
 122 // CHECK: done
 123 // CHECK: done
 124 // CHECK: done