1 // RUN: %clang_tsan -O1 %s -o %t && %run %t 2>&1 | FileCheck %s
2
3 // Test case for recursive signal handlers, adopted from:
4 // https://github.com/google/sanitizers/issues/478
5
6 // REQUIRES: disabled
7
8 #include "test.h"
9 #include <semaphore.h>
10 #include <signal.h>
11 #include <errno.h>
12
13 static const int kSigSuspend = SIGUSR1;
14 static const int kSigRestart = SIGUSR2;
15
16 static sem_t g_thread_suspend_ack_sem;
17
18 static bool g_busy_thread_received_restart;
19
20 static volatile bool g_busy_thread_garbage_collected;
21
SaveRegistersInStack()22 static void SaveRegistersInStack() {
23 // Mono walks thread stacks to detect unreferenced objects.
24 // If last object reference is kept in register the object will be collected
25 // This is why threads can't be suspended with something like pthread_suspend
26 }
27
fail(const char * what)28 static void fail(const char *what) {
29 fprintf(stderr, "FAILED: %s (errno=%d)\n", what, errno);
30 exit(1);
31 }
32
SuspendHandler(int sig)33 static void SuspendHandler(int sig) {
34 int old_errno = errno;
35 SaveRegistersInStack();
36
37 // Enable kSigRestart handling, tsan disables signals around signal handlers.
38 sigset_t sigset;
39 sigemptyset(&sigset);
40 pthread_sigmask(SIG_SETMASK, &sigset, 0);
41
42 // Acknowledge that thread is saved and suspended
43 if (sem_post(&g_thread_suspend_ack_sem) != 0)
44 fail("sem_post failed");
45
46 // Wait for wakeup signal.
47 while (!g_busy_thread_received_restart)
48 usleep(100); // wait for kSigRestart signal
49
50 // Acknowledge that thread restarted
51 if (sem_post(&g_thread_suspend_ack_sem) != 0)
52 fail("sem_post failed");
53
54 g_busy_thread_garbage_collected = true;
55
56 errno = old_errno;
57 }
58
RestartHandler(int sig)59 static void RestartHandler(int sig) {
60 g_busy_thread_received_restart = true;
61 }
62
StopWorld(pthread_t thread)63 static void StopWorld(pthread_t thread) {
64 if (pthread_kill(thread, kSigSuspend) != 0)
65 fail("pthread_kill failed");
66
67 while (sem_wait(&g_thread_suspend_ack_sem) != 0) {
68 if (errno != EINTR)
69 fail("sem_wait failed");
70 }
71 }
72
StartWorld(pthread_t thread)73 static void StartWorld(pthread_t thread) {
74 if (pthread_kill(thread, kSigRestart) != 0)
75 fail("pthread_kill failed");
76
77 while (sem_wait(&g_thread_suspend_ack_sem) != 0) {
78 if (errno != EINTR)
79 fail("sem_wait failed");
80 }
81 }
82
CollectGarbage(pthread_t thread)83 static void CollectGarbage(pthread_t thread) {
84 StopWorld(thread);
85 // Walk stacks
86 StartWorld(thread);
87 }
88
Init()89 static void Init() {
90 if (sem_init(&g_thread_suspend_ack_sem, 0, 0) != 0)
91 fail("sem_init failed");
92
93 struct sigaction act = {};
94 act.sa_flags = SA_RESTART;
95 act.sa_handler = &SuspendHandler;
96 if (sigaction(kSigSuspend, &act, NULL) != 0)
97 fail("sigaction failed");
98 act.sa_handler = &RestartHandler;
99 if (sigaction(kSigRestart, &act, NULL) != 0)
100 fail("sigaction failed");
101 }
102
BusyThread(void * arg)103 void* BusyThread(void *arg) {
104 (void)arg;
105 while (!g_busy_thread_garbage_collected) {
106 usleep(100); // Tsan deadlocks without these sleeps
107 }
108 return NULL;
109 }
110
main(int argc,const char * argv[])111 int main(int argc, const char *argv[]) {
112 Init();
113 pthread_t busy_thread;
114 if (pthread_create(&busy_thread, NULL, &BusyThread, NULL) != 0)
115 fail("pthread_create failed");
116 CollectGarbage(busy_thread);
117 if (pthread_join(busy_thread, 0) != 0)
118 fail("pthread_join failed");
119 fprintf(stderr, "DONE\n");
120 return 0;
121 }
122
123 // CHECK-NOT: FAILED
124 // CHECK-NOT: ThreadSanitizer CHECK failed
125 // CHECK-NOT: WARNING: ThreadSanitizer:
126 // CHECK: DONE
127