114 lines · cpp
1// RUN: %clang_tsan %s -lstdc++ -o %t && %run %t 2>&1 | FileCheck %s2 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 17int 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.27class Mutex {28public: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 53private:54 int value;55};56 57Mutex mutex;58 59void *Thread(void *x) {60 // Waiting for the futex.61 mutex.lock();62 // Finished waiting.63 return nullptr;64}65 66static void SigprofHandler(int signal, siginfo_t *info, void *context) {67 // Unlock the futex.68 mutex.unlock();69}70 71void 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 82int main() {83 alarm(60); // Kill the test if it hangs.84 85 // Install the signal handler86 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_PRIVATE96 // 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 wake100 // 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: PASS114