compiler-rt/test/tsan/Linux/signal_in_futex_wait.cpp

   1 // RUN: %clang_tsan %s -lstdc++ -o %t && %run %t 2>&1 | FileCheck %s
   2
   3 #include "../test.h"
   4 #include <errno.h>
   5 #include <linux/futex.h>
   6 #include <pthread.h>
   7 #include <signal.h>
   8 #include <stdio.h>
   9 #include <sys/syscall.h>
  10
  11 #include <cassert>
  12 #include <stdexcept>
  13 #include <thread>
  14
  15 #include <sanitizer/linux_syscall_hooks.h>
  16
  17 int futex(int *uaddr, int futex_op, int val, const struct timespec *timeout,
  18           int *uaddr2, int val3) {
  19   __sanitizer_syscall_pre_futex(uaddr, futex_op, val, timeout, uaddr2, val3);
  20   int result = syscall(SYS_futex, uaddr, futex_op, val, timeout, uaddr2, val3);
  21   __sanitizer_syscall_post_futex(result, uaddr, futex_op, val, timeout, uaddr2,
  22                                  val3);
  23   return result;
  24 }
  25
  26 // Simple mutex implementation using futex.
  27 class Mutex {
  28 public:
  29   Mutex() : value(0) {}
  30
  31   void lock() {
  32     int c;
  33     while ((c = __sync_val_compare_and_swap(&value, 0, 1)) != 0) {
  34       if (c != 1)
  35         continue;
  36       int r = futex(&value, FUTEX_WAIT_PRIVATE, 1, nullptr, nullptr, 0);
  37       if (r == -1 && errno != EAGAIN) {
  38         fprintf(stderr, "futex wait error\n");
  39         abort();
  40       }
  41     }
  42   }
  43
  44   void unlock() {
  45     value = 0;
  46     int r = futex(&value, FUTEX_WAKE_PRIVATE, 1, nullptr, nullptr, 0);
  47     if (r == -1) {
  48       fprintf(stderr, "futex wake error\n");
  49       abort();
  50     }
  51   }
  52
  53 private:
  54   int value;
  55 };
  56
  57 Mutex mutex;
  58
  59 void *Thread(void *x) {
  60   // Waiting for the futex.
  61   mutex.lock();
  62   // Finished waiting.
  63   return nullptr;
  64 }
  65
  66 static void SigprofHandler(int signal, siginfo_t *info, void *context) {
  67   // Unlock the futex.
  68   mutex.unlock();
  69 }
  70
  71 void InstallSignalHandler() {
  72   struct sigaction sa;
  73   sa.sa_sigaction = SigprofHandler;
  74   sigemptyset(&sa.sa_mask);
  75   sa.sa_flags = SA_RESTART | SA_SIGINFO;
  76   if (sigaction(SIGPROF, &sa, 0) != 0) {
  77     fprintf(stderr, "failed to install signal handler\n");
  78     abort();
  79   }
  80 }
  81
  82 int main() {
  83   alarm(60); // Kill the test if it hangs.
  84
  85   // Install the signal handler
  86   InstallSignalHandler();
  87
  88   // Lock the futex at first so the other thread will wait for it.
  89   mutex.lock();
  90
  91   // Create the thread to wait for the futex.
  92   pthread_t thread;
  93   pthread_create(&thread, NULL, Thread, NULL);
  94
  95   // Just waiting a bit to make sure the thead is at the FUTEX_WAIT_PRIVATE
  96   // syscall.
  97   std::this_thread::sleep_for(std::chrono::milliseconds(100));
  98
  99   // Send the signal to the other thread, which will send the futex wake
 100   // syscall.
 101   int r = pthread_kill(thread, SIGPROF);
 102   assert(r == 0);
 103
 104   // Futex should be notified and the thread should be able to continue.
 105   pthread_join(thread, NULL);
 106
 107   // Exiting successfully.
 108   fprintf(stderr, "PASS\n");
 109   return 0;
 110 }
 111
 112 // CHECK-NOT: WARNING: ThreadSanitizer:
 113 // CHECK: PASS