block all signals in listener thread

[ust.git] / libust / tracectl.c

diff --git a/libust/tracectl.c b/libust/tracectl.c
index 3624b867f6d9f7a39bcae586878b00ae3abdd0b2..7a5cf9562282ce7fe90cc3d5e4c405d3bf44b8c6 100644 (file)
--- a/libust/tracectl.c
+++ b/libust/tracectl.c
@@ -19,6 +19,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdint.h>
+#include <pthread.h>
 #include <signal.h>
 #include <sys/types.h>
 #include <sys/socket.h>
@@ -1031,17 +1032,38 @@ static pthread_t listener_thread;
 void create_listener(void)
 {
        int result;
+       sigset_t sig_all_blocked;
+       sigset_t orig_parent_mask;
 
        if(have_listener) {
                WARN("not creating listener because we already had one");
                return;
        }
 
+       /* A new thread created by pthread_create inherits the signal mask
+        * from the parent. To avoid any signal being received by the
+        * listener thread, we block all signals temporarily in the parent,
+        * while we create the listener thread.
+        */
+
+       sigfillset(&sig_all_blocked);
+
+       result = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_parent_mask);
+       if(result) {
+               PERROR("pthread_sigmask: %s", strerror(result));
+       }
+
        result = pthread_create(&listener_thread, NULL, listener_main, NULL);
        if(result == -1) {
                PERROR("pthread_create");
        }
 
+       /* Restore original signal mask in parent */
+       result = pthread_sigmask(SIG_SETMASK, &orig_parent_mask, NULL);
+       if(result) {
+               PERROR("pthread_sigmask: %s", strerror(result));
+       }
+
        have_listener = 1;
 }