X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fcode%2Fthread.lisp;h=a780b16887ad4e72fd9c14f2465f7946233be14d;hb=d94c1b4a8c534bde146823f56558faf37cd4c4d7;hp=6e427886bb35acf9e265b3acf24e4122c2c0ab6d;hpb=4255b37e50876702d2563f3418a44a3f5bf8a2e8;p=sbcl.git

diff --git a/src/code/thread.lisp b/src/code/thread.lisp
index 6e42788..a780b16 100644
--- a/src/code/thread.lisp
+++ b/src/code/thread.lisp
@@ -107,15 +107,22 @@ stale value, use MUTEX-OWNER instead."
                     'progn
                     'with-local-interrupts)))
       `(let* ((,thread *current-thread*)
-              (,prev (thread-waiting-for ,thread)))
+              (,prev (progn
+                       (barrier (:read))
+                       (thread-waiting-for ,thread))))
          (flet ((exec () ,@body))
            (if ,prev
                (,without
                 (unwind-protect
                      (progn
                        (setf (thread-waiting-for ,thread) nil)
+                       (barrier (:write))
                        (,with (exec)))
-                  (setf (thread-waiting-for ,thread) ,prev)))
+                  ;; If we were waiting on a waitqueue, this becomes a bogus
+                  ;; wakeup.
+                  (when (mutex-p ,prev)
+                    (setf (thread-waiting-for ,thread) ,prev)
+                    (barrier (:write)))))
                (exec)))))))
 
 (sb!xc:defmacro with-mutex ((mutex &key (value '*current-thread*) (wait-p t))