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