1.0.24.26: fix release spinlock

[sbcl.git] / src / runtime / x86-arch.h

diff --git a/src/runtime/x86-arch.h b/src/runtime/x86-arch.h
index 30363db..2dfac47 100644 (file)
--- a/src/runtime/x86-arch.h
+++ b/src/runtime/x86-arch.h
@@ -29,13 +29,13 @@ get_spinlock(volatile lispobj *word, unsigned long value)
         lose("recursive get_spinlock: 0x%x,%ld\n",word,value);
     do {
 #if defined(LISP_FEATURE_DARWIN)
-        asm ("xor %0,%0;\n\
+        asm volatile ("xor %0,%0;\n\
               lock/cmpxchg %1,%2"
              : "=a" (eax)
              : "r" (value), "m" (*word)
              : "memory", "cc");
 #else
-        asm ("xor %0,%0\n\
+        asm volatile ("xor %0,%0\n\
               lock cmpxchg %1,%2"
              : "=a" (eax)
              : "r" (value), "m" (*word)
@@ -48,12 +48,6 @@ get_spinlock(volatile lispobj *word, unsigned long value)
 #endif
 }
 
-static inline void
-release_spinlock(volatile lispobj *word)
-{
-    *word=0;
-}
-
 #include <stdio.h>
 
 static inline lispobj
@@ -61,12 +55,12 @@ swap_lispobjs(volatile lispobj *dest, lispobj value)
 {
     lispobj old_value;
 #if defined(LISP_FEATURE_DARWIN)
-    asm ("lock/xchg %0,(%1)"
+    asm volatile ("lock/xchg %0,(%1)"
          : "=r" (old_value)
          : "r" (dest), "0" (value)
          : "memory");
 #else
-    asm ("lock xchg %0,(%1)"
+    asm volatile ("lock xchg %0,(%1)"
          : "=r" (old_value)
          : "r" (dest), "0" (value)
          : "memory");
@@ -74,6 +68,14 @@ swap_lispobjs(volatile lispobj *dest, lispobj value)
     return old_value;
 }
 
+static inline void
+release_spinlock(volatile lispobj *word)
+{
+    /* A memory barrier is needed, use swap_lispobjs. See comment in
+     * RELEASE-SPINLOCK in target-thread.lisp. */
+    swap_lispobjs(word,0);
+}
+
 extern void fast_bzero_detect(void *, size_t);
 extern void (*fast_bzero_pointer)(void *, size_t);