1.0.26.15: interrupt.c refactoring

[sbcl.git] / src / runtime / gc-common.c

diff --git a/src/runtime/gc-common.c b/src/runtime/gc-common.c
index fb006cb..c358039 100644 (file)
--- a/src/runtime/gc-common.c
+++ b/src/runtime/gc-common.c
@@ -1885,7 +1885,7 @@ scav_lose(lispobj *where, lispobj object)
 {
     lose("no scavenge function for object 0x%08x (widetag 0x%x)\n",
          (unsigned long)object,
-         widetag_of(*(lispobj*)native_pointer(object)));
+         widetag_of(object));
 
     return 0; /* bogus return value to satisfy static type checking */
 }
@@ -2406,9 +2406,8 @@ gc_search_space(lispobj *start, size_t words, lispobj *pointer)
 boolean
 maybe_gc(os_context_t *context)
 {
-#ifndef LISP_FEATURE_WIN32
+    lispobj gc_happened;
     struct thread *thread = arch_os_get_current_thread();
-#endif
 
     fake_foreign_function_call(context);
     /* SUB-GC may return without GCing if *GC-INHIBIT* is set, in
@@ -2434,32 +2433,41 @@ maybe_gc(os_context_t *context)
      * outer context.
      */
 #ifndef LISP_FEATURE_WIN32
-    if(SymbolValue(INTERRUPTS_ENABLED,thread)!=NIL) {
+    check_gc_signals_unblocked_or_lose(os_context_sigmask_addr(context));
+    unblock_gc_signals(0, 0);
+#endif
+    FSHOW((stderr, "/maybe_gc: calling SUB_GC\n"));
+    /* FIXME: Nothing must go wrong during GC else we end up running
+     * the debugger, error handlers, and user code in general in a
+     * potentially unsafe place. Running out of the control stack or
+     * the heap in SUB-GC are ways to lose. Of course, deferrables
+     * cannot be unblocked because there may be a pending handler, or
+     * we may even be in a WITHOUT-INTERRUPTS. */
+    gc_happened = funcall0(StaticSymbolFunction(SUB_GC));
+    FSHOW((stderr, "/maybe_gc: gc_happened=%s\n",
+           (gc_happened == NIL) ? "NIL" : "T"));
+    if ((gc_happened != NIL) &&
+        /* See if interrupts are enabled or it's possible to enable
+         * them. POST-GC has a similar check, but we don't want to
+         * unlock deferrables in that case and get a pending interrupt
+         * here. */
+        ((SymbolValue(INTERRUPTS_ENABLED,thread) != NIL) ||
+         (SymbolValue(ALLOW_WITH_INTERRUPTS,thread) != NIL))) {
+#ifndef LISP_FEATURE_WIN32
         sigset_t *context_sigmask = os_context_sigmask_addr(context);
-#ifdef LISP_FEATURE_SB_THREAD
-        /* What if the context we'd like to restore has GC signals
-         * blocked? Just skip the GC: we can't set GC_PENDING, because
-         * that would block the next attempt, and we don't know when
-         * we'd next check for it -- and it's hard to be sure that
-         * unblocking would be safe.
-         *
-         * FIXME: This is not actually much better: we may already have
-         * GC_PENDING set, and presumably our caller assumes that we will
-         * clear it. Perhaps we should, even though we don't actually GC? */
-        if (sigismember(context_sigmask,SIG_STOP_FOR_GC)) {
-            undo_fake_foreign_function_call(context);
-            return 1;
+        if (!deferrables_blocked_p(context_sigmask)) {
+            thread_sigmask(SIG_SETMASK, context_sigmask, 0);
+            check_gc_signals_unblocked_or_lose(0);
+#endif
+            FSHOW((stderr, "/maybe_gc: calling POST_GC\n"));
+            funcall0(StaticSymbolFunction(POST_GC));
+#ifndef LISP_FEATURE_WIN32
+        } else {
+            FSHOW((stderr, "/maybe_gc: punting on POST_GC due to blockage\n"));
         }
 #endif
-        thread_sigmask(SIG_SETMASK, context_sigmask, 0);
     }
-    else
-        unblock_gc_signals();
-#endif
-    /* SIG_STOP_FOR_GC needs to be enabled before we can call lisp:
-     * otherwise two threads racing here may deadlock: the other will
-     * wait on the GC lock, and the other cannot stop the first one... */
-    funcall0(StaticSymbolFunction(SUB_GC));
     undo_fake_foreign_function_call(context);
-    return 1;
+    FSHOW((stderr, "/maybe_gc: returning\n"));
+    return (gc_happened != NIL);
 }