Fixed wxAtomicInc/Dec() to not use asm/atomic.h header on Linux - it's kernel internal, not available for userspace in newer kernel versions and broken for userspace on some platforms. Use GCC's builtins instead.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@48640 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

aclocal.m4

@@ -12,6 +12,7 @@
 # PARTICULAR PURPOSE.
 
 m4_include([build/aclocal/ac_raf_func_which_getservbyname_r.m4])
+m4_include([build/aclocal/atomic_builtins.m4])
 m4_include([build/aclocal/ax_func_which_gethostbyname_r.m4])
 m4_include([build/aclocal/bakefile-dllar.m4])
 m4_include([build/aclocal/bakefile-lang.m4])

build/aclocal/atomic_builtins.m4

@@ -0,0 +1,26 @@
+
+dnl Checks for availability of GCC's atomic operations builtins.
+dnl Defines HAVE_GCC_ATOMIC_BUILTINS if available.
+
+AC_DEFUN([WX_ATOMIC_BUILTINS],
+[
+  AC_REQUIRE([AC_PROG_CC])
+  if test -n "$GCC"; then
+    AC_MSG_CHECKING([for __sync_fetch_* builtins])
+    AC_CACHE_VAL(wx_cv_cc_gcc_atomic_builtins, [
+      AC_TRY_COMPILE(
+        [],
+        [
+          int value=0;
+          __sync_fetch_and_add(&value, 1);
+          __sync_sub_and_fetch(&value, 1);
+        ],
+        wx_cv_cc_gcc_atomic_builtins=yes,
+        wx_cv_cc_gcc_atomic_builtins=no)
+      ])
+    AC_MSG_RESULT([$wx_cv_cc_gcc_atomic_builtins])
+    if test $wx_cv_cc_gcc_atomic_builtins = yes; then
+      AC_DEFINE([HAVE_GCC_ATOMIC_BUILTINS])
+    fi
+  fi
+])

configure.in

@@ -1987,6 +1987,9 @@ if test "$wxUSE_STL" = "yes"; then
     fi
 fi
 
+dnl check for atomic operations builtins for wx/atomic.h:
+WX_ATOMIC_BUILTINS
+
 dnl pop C++
 AC_LANG_POP()
 

include/wx/atomic.h

@@ -25,7 +25,25 @@
 
 #if wxUSE_THREADS
 
-#if defined(__WXMSW__)
+#if defined(HAVE_GCC_ATOMIC_BUILTINS)
+
+// NB: we intentionally don't use Linux's asm/atomic.h header, because it's
+//     an internal kernel header that doesn't always work in userspace:
+//     http://bugs.mysql.com/bug.php?id=28456
+//     http://golubenco.org/blog/atomic-operations/
+
+inline void wxAtomicInc (wxUint32 &value)
+{
+    __sync_fetch_and_add(&value, 1);
+}
+
+inline wxUint32 wxAtomicDec (wxUint32 &value)
+{
+    return __sync_sub_and_fetch(&value, 1);
+}
+
+
+#elif defined(__WXMSW__)
 
 // include standard Windows headers
 #include "wx/msw/wrapwin.h"
@@ -53,20 +71,6 @@ inline wxUint32 wxAtomicDec (wxUint32 &value)
     return OSAtomicDecrement32 ((int32_t*)&value);
 }
 
-#elif defined(__LINUX__)
-
-#include <asm/atomic.h>
-
-inline void wxAtomicInc (wxUint32 &value)
-{
-    atomic_inc ((atomic_t*)&value);
-}
-
-inline wxUint32 wxAtomicDec (wxUint32 &value)
-{
-    return atomic_dec_and_test ((atomic_t*)&value) ? 0 : 1;
-}
-
 #elif defined (__SOLARIS__)
 
 #include <atomic.h>

setup.h.in

@@ -675,6 +675,11 @@
  */
 #undef HAVE_VISIBILITY
 
+/*
+ * Define if the compiler supports GCC's atomic memory access builtins
+ */
+#undef HAVE_GCC_ATOMIC_BUILTINS
+
 /*
  * Define if compiler's visibility support in libstdc++ is broken
  */

setup.h_vms

@@ -674,6 +674,11 @@ typedef pid_t GPid;
  */
 #undef HAVE_VISIBILITY
 
+/*
+ * Define if the compiler supports GCC's atomic memory access builtins
+ */
+#undef HAVE_GCC_ATOMIC_BUILTINS
+
 /*
  * The built-in regex supports advanced REs in additional to POSIX's basic
  * and extended. Your system regex probably won't support this, and in this