int result, lock_ret;
FSHOW((stderr,"/creating thread %lu\n", thread_self()));
+ check_deferrables_blocked_or_lose();
+ check_gc_signals_unblocked_or_lose();
function = th->no_tls_value_marker;
th->no_tls_value_marker = NO_TLS_VALUE_MARKER_WIDETAG;
if(arch_os_thread_init(th)==0) {
th->os_thread=thread_self();
protect_control_stack_guard_page(1);
/* Since GC can only know about this thread from the all_threads
- * list and we're just adding this thread to it there is no danger
- * of deadlocking even with SIG_STOP_FOR_GC blocked (which it is
- * not). */
+ * list and we're just adding this thread to it, there is no
+ * danger of deadlocking even with SIG_STOP_FOR_GC blocked (which
+ * it is not). */
lock_ret = pthread_mutex_lock(&all_threads_lock);
gc_assert(lock_ret == 0);
link_thread(th);
{
/* The new thread inherits the restrictive signal mask set here,
* and enables signals again when it is set up properly. */
- sigset_t newset,oldset;
+ sigset_t oldset;
boolean r=1;
int retcode = 0, initcode;
FSHOW_SIGNAL((stderr,"/create_os_thread: creating new thread\n"));
+ /* Blocking deferrable signals is enough, no need to block
+ * SIG_STOP_FOR_GC because the child process is not linked onto
+ * all_threads until it's ready. */
+ thread_sigmask(SIG_BLOCK, &deferrable_sigset, &oldset);
+
#ifdef LOCK_CREATE_THREAD
retcode = pthread_mutex_lock(&create_thread_lock);
gc_assert(retcode == 0);
FSHOW_SIGNAL((stderr,"/create_os_thread: got lock\n"));
#endif
- sigemptyset(&newset);
- /* Blocking deferrable signals is enough, no need to block
- * SIG_STOP_FOR_GC because the child process is not linked onto
- * all_threads until it's ready. */
- sigaddset_deferrable(&newset);
- thread_sigmask(SIG_BLOCK, &newset, &oldset);
if((initcode = pthread_attr_init(th->os_attr)) ||
/* call_into_lisp_first_time switches the stack for the initial thread. For the
r=0;
}
- thread_sigmask(SIG_SETMASK,&oldset,0);
#ifdef LOCK_CREATE_THREAD
retcode = pthread_mutex_unlock(&create_thread_lock);
gc_assert(retcode == 0);
FSHOW_SIGNAL((stderr,"/create_os_thread: released lock\n"));
#endif
+ thread_sigmask(SIG_SETMASK,&oldset,0);
return r;
}
os_thread_t create_thread(lispobj initial_function) {
- struct thread *th;
- os_thread_t kid_tid;
+ struct thread *th, *thread = arch_os_get_current_thread();
+ os_thread_t kid_tid = 0;
+ /* Must defend against async unwinds. */
+ if (SymbolValue(INTERRUPTS_ENABLED, thread) != NIL)
+ lose("create_thread is not safe when interrupts are enabled.\n");
+
/* Assuming that a fresh thread struct has no lisp objects in it,
* linking it to all_threads can be left to the thread itself
* without fear of gc lossage. initial_function violates this
* assumption and must stay pinned until the child starts up. */
th = create_thread_struct(initial_function);
- if(th==0) return 0;
-
- if (create_os_thread(th,&kid_tid)) {
- return kid_tid;
- } else {
+ if (th && !create_os_thread(th,&kid_tid)) {
free_thread_struct(th);
- return 0;
- }
-}
-
-int signal_interrupt_thread(os_thread_t os_thread)
-{
- int status = pthread_kill(os_thread, SIG_INTERRUPT_THREAD);
- FSHOW_SIGNAL((stderr,"/signal_interrupt_thread: %lu\n", os_thread));
- if (status == 0) {
- return 0;
- } else if (status == ESRCH) {
- return -1;
- } else {
- lose("cannot send SIG_INTERRUPT_THREAD to thread=%lu: %d, %s\n",
- os_thread, status, strerror(status));
+ kid_tid = 0;
}
+ return kid_tid;
}
/* stopping the world is a two-stage process. From this thread we signal
if((p!=th) && ((thread_state(p)==STATE_RUNNING))) {
FSHOW_SIGNAL((stderr,"/gc_stop_the_world: suspending thread %lu\n",
p->os_thread));
+ /* We already hold all_thread_lock, P can become DEAD but
+ * cannot exit, ergo it's safe to use pthread_kill. */
status=pthread_kill(p->os_thread,SIG_STOP_FOR_GC);
if (status==ESRCH) {
/* This thread has exited. */
return 0;
#endif
}
+
+/* If the thread id given does not belong to a running thread (it has
+ * exited or never even existed) pthread_kill _may_ fail with ESRCH,
+ * but it is also allowed to just segfault, see
+ * <http://udrepper.livejournal.com/16844.html>.
+ *
+ * Relying on thread ids can easily backfire since ids are recycled
+ * (NPTL recycles them extremely fast) so a signal can be sent to
+ * another process if the one it was sent to exited.
+ *
+ * We send signals in two places: signal_interrupt_thread sends a
+ * signal that's harmless if delivered to another thread, but
+ * SIG_STOP_FOR_GC is fatal.
+ *
+ * For these reasons, we must make sure that the thread is still alive
+ * when the pthread_kill is called and return if the thread is
+ * exiting. */
+int
+kill_safely(os_thread_t os_thread, int signal)
+{
+#ifdef LISP_FEATURE_SB_THREAD
+ sigset_t oldset;
+ struct thread *thread;
+ /* pthread_kill is not async signal safe and we don't want to be
+ * interrupted while holding the lock. */
+ thread_sigmask(SIG_BLOCK, &deferrable_sigset, &oldset);
+ pthread_mutex_lock(&all_threads_lock);
+ for (thread = all_threads; thread; thread = thread->next) {
+ if (thread->os_thread == os_thread) {
+ int status = pthread_kill(os_thread, signal);
+ if (status)
+ lose("kill_safely: pthread_kill failed with %d\n", status);
+ break;
+ }
+ }
+ pthread_mutex_unlock(&all_threads_lock);
+ thread_sigmask(SIG_SETMASK,&oldset,0);
+ if (thread)
+ return 0;
+ else
+ return -1;
+#else
+ int status;
+ if (os_thread != 0)
+ lose("kill_safely: who do you want to kill? %d?\n", os_thread);
+ status = raise(signal);
+ if (status == 0) {
+ return 0;
+ } else {
+ lose("cannot raise signal %d, %d %s\n",
+ signal, status, strerror(errno));
+ }
+#endif
+}
projects / sbcl.git / blobdiff