utils: fix lxc_set_death_signal()

src/lxc/start.c

@@ -1052,7 +1052,7 @@ static int do_start(void *data)
 	 * exit before we set the pdeath signal leading to a unsupervized
 	 * container.
 	 */
-	ret = lxc_set_death_signal(SIGKILL);
+	ret = lxc_set_death_signal(SIGKILL, 0);
 	if (ret < 0) {
 		SYSERROR("Failed to set PR_SET_PDEATHSIG to SIGKILL");
 		goto out_warn_father;
@@ -1130,7 +1130,7 @@ static int do_start(void *data)
 			goto out_warn_father;
 
 		/* set{g,u}id() clears deathsignal */
-		ret = lxc_set_death_signal(SIGKILL);
+		ret = lxc_set_death_signal(SIGKILL, 0);
 		if (ret < 0) {
 			SYSERROR("Failed to set PR_SET_PDEATHSIG to SIGKILL");
 			goto out_warn_father;

src/lxc/utils.c

@@ -1645,7 +1645,7 @@ uint64_t lxc_find_next_power2(uint64_t n)
 	return n;
 }
 
-int lxc_set_death_signal(int signal)
+int lxc_set_death_signal(int signal, pid_t parent)
 {
 	int ret;
 	pid_t ppid;
@@ -1655,11 +1655,8 @@ int lxc_set_death_signal(int signal)
 
 	/* Check whether we have been orphaned. */
 	ppid = (pid_t)syscall(SYS_getppid);
-	if (ppid == 1) {
-		pid_t self;
-
-		self = lxc_raw_getpid();
-		ret = kill(self, SIGKILL);
+	if (ppid != parent) {
+		ret = raise(SIGKILL);
 		if (ret < 0)
 			return -1;
 	}

src/lxc/utils.h

@@ -433,7 +433,7 @@ static inline pid_t lxc_raw_gettid(void)
 }
 
 /* Set a signal the child process will receive after the parent has died. */
-extern int lxc_set_death_signal(int signal);
+extern int lxc_set_death_signal(int signal, pid_t parent);
 extern int fd_cloexec(int fd, bool cloexec);
 extern int recursive_destroy(char *dirname);
 extern int lxc_setup_keyring(void);