Merge branch 'stdatomic' into 'master'

sysdeps: Use C11 stdatomic.h where possible

See merge request dbus/dbus!431

cmake/ConfigureChecks.cmake

@@ -21,6 +21,7 @@ check_include_file(linux/close_range.h HAVE_LINUX_CLOSE_RANGE_H)
 check_include_file(linux/magic.h HAVE_LINUX_MAGIC_H)
 check_include_file(locale.h     HAVE_LOCALE_H)
 check_include_file(signal.h     HAVE_SIGNAL_H)
+check_include_file(stdatomic.h  HAVE_STDATOMIC_H)
 check_include_file(stdio.h      HAVE_STDIO_H)   # dbus-sysdeps.h
 check_include_files("stdint.h;sys/types.h;sys/event.h" HAVE_SYS_EVENT_H)
 check_include_file(sys/inotify.h     HAVE_SYS_INOTIFY_H)

cmake/config.h.cmake

@@ -113,6 +113,7 @@
 /* Define to 1 if you have stdio.h */
 #cmakedefine   HAVE_STDIO_H 1
 
+#cmakedefine HAVE_STDATOMIC_H 1
 #cmakedefine HAVE_SYSLOG_H 1
 #cmakedefine HAVE_SYS_EVENTS_H 1
 #cmakedefine HAVE_SYS_INOTIFY_H 1

configure.ac

@@ -419,6 +419,7 @@ errno.h
 linux/close_range.h
 locale.h
 signal.h
+stdatomic.h
 sys/prctl.h
 sys/random.h
 sys/resource.h

dbus/CMakeLists.txt

@@ -185,6 +185,7 @@ if(WIN32)
         dbus-sysdeps-thread-win.c
     )
     set(DBUS_SHARED_HEADERS ${DBUS_SHARED_HEADERS}
+        dbus-init-win.h
         dbus-sockets-win.h
         dbus-sysdeps-win.h
     )

dbus/Makefile.am

@@ -77,6 +77,7 @@ DBUS_SHARED_arch_sources = 			\
 	$(wince_source)				\
 	dbus-backtrace-win.c 			\
 	dbus-file-win.c 			\
+	dbus-init-win.h 			\
 	dbus-pipe-win.c 			\
 	dbus-sockets-win.h			\
 	dbus-sysdeps-win.c 			\

dbus/dbus-init-win.cpp

@@ -27,7 +27,7 @@
 
 extern "C"
 {
-#include "dbus-sysdeps-win.h"
+#include "dbus-init-win.h"
 }
 
 class DBusInternalInit

dbus/dbus-init-win.h

@@ -0,0 +1,17 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
+/*
+ * Copyright © 2013 Intel Corporation
+ * SPDX-License-Identifier: AFL-2.1 OR GPL-2.0-or-later
+ *
+ * Do not include other private headers in this one, particularly
+ * dbus-sysdeps.h: it gets included into C++ code which is not
+ * compatible with our use of <stdatomic.h>.
+ */
+
+#ifndef DBUS_INIT_WIN_H
+#define DBUS_INIT_WIN_H
+
+void        _dbus_threads_windows_init_global (void);
+void        _dbus_threads_windows_ensure_ctor_linked (void);
+
+#endif

dbus/dbus-sysdeps-thread-win.c

@@ -24,6 +24,7 @@
  */
 
 #include <config.h>
+#include "dbus-init-win.h"
 #include "dbus-internals.h"
 #include "dbus-sysdeps.h"
 #include "dbus-sysdeps-win.h"

dbus/dbus-sysdeps-unix.c

@@ -98,7 +98,7 @@
 #include <systemd/sd-daemon.h>
 #endif
 
-#if !DBUS_USE_SYNC
+#if !defined(HAVE_STDATOMIC_H) && !DBUS_USE_SYNC
 #include <pthread.h>
 #endif
 
@@ -3141,7 +3141,7 @@ _dbus_pid_for_log (void)
   return getpid ();
 }
 
-#if !DBUS_USE_SYNC
+#if !defined(HAVE_STDATOMIC_H) && !DBUS_USE_SYNC
 /* To be thread-safe by default on platforms that don't necessarily have
  * atomic operations (notably Debian armel, which is armv4t), we must
  * use a mutex that can be initialized statically, like this.
@@ -3159,7 +3159,11 @@ static pthread_mutex_t atomic_mutex = PTHREAD_MUTEX_INITIALIZER;
 dbus_int32_t
 _dbus_atomic_inc (DBusAtomic *atomic)
 {
-#if DBUS_USE_SYNC
+#ifdef HAVE_STDATOMIC_H
+  /* Atomic version of "old = *atomic; *atomic += 1; return old" */
+  return atomic_fetch_add (&atomic->value, 1);
+#elif DBUS_USE_SYNC
+  /* Atomic version of "*atomic += 1; return *atomic - 1" */
   return __sync_add_and_fetch(&atomic->value, 1)-1;
 #else
   dbus_int32_t res;
@@ -3182,7 +3186,11 @@ _dbus_atomic_inc (DBusAtomic *atomic)
 dbus_int32_t
 _dbus_atomic_dec (DBusAtomic *atomic)
 {
-#if DBUS_USE_SYNC
+#ifdef HAVE_STDATOMIC_H
+  /* Atomic version of "old = *atomic; *atomic -= 1; return old" */
+  return atomic_fetch_sub (&atomic->value, 1);
+#elif DBUS_USE_SYNC
+  /* Atomic version of "*atomic -= 1; return *atomic + 1" */
   return __sync_sub_and_fetch(&atomic->value, 1)+1;
 #else
   dbus_int32_t res;
@@ -3206,7 +3214,10 @@ _dbus_atomic_dec (DBusAtomic *atomic)
 dbus_int32_t
 _dbus_atomic_get (DBusAtomic *atomic)
 {
-#if DBUS_USE_SYNC
+#ifdef HAVE_STDATOMIC_H
+  /* Atomic version of "return *atomic" */
+  return atomic_load (&atomic->value);
+#elif DBUS_USE_SYNC
   __sync_synchronize ();
   return atomic->value;
 #else
@@ -3228,7 +3239,10 @@ _dbus_atomic_get (DBusAtomic *atomic)
 void
 _dbus_atomic_set_zero (DBusAtomic *atomic)
 {
-#if DBUS_USE_SYNC
+#ifdef HAVE_STDATOMIC_H
+  /* Atomic version of "*atomic = 0" */
+  atomic_store (&atomic->value, 0);
+#elif DBUS_USE_SYNC
   /* Atomic version of "*atomic &= 0; return *atomic" */
   __sync_and_and_fetch (&atomic->value, 0);
 #else
@@ -3246,7 +3260,10 @@ _dbus_atomic_set_zero (DBusAtomic *atomic)
 void
 _dbus_atomic_set_nonzero (DBusAtomic *atomic)
 {
-#if DBUS_USE_SYNC
+#ifdef HAVE_STDATOMIC_H
+  /* Atomic version of "*atomic = 1" */
+  atomic_store (&atomic->value, 1);
+#elif DBUS_USE_SYNC
   /* Atomic version of "*atomic |= 1; return *atomic" */
   __sync_or_and_fetch (&atomic->value, 1);
 #else

dbus/dbus-sysdeps-win.c

@@ -3452,9 +3452,13 @@ _dbus_make_file_world_readable(const DBusString *filename,
 dbus_int32_t
 _dbus_atomic_inc (DBusAtomic *atomic)
 {
-  // +/- 1 is needed here!
-  // no volatile argument with mingw
+#ifdef HAVE_STDATOMIC_H
+  /* Atomic version of "old = *atomic; *atomic += 1; return old" */
+  return atomic_fetch_add (&atomic->value, 1);
+#else
+  /* Atomic version of "*atomic += 1; return *atomic - 1" */
   return InterlockedIncrement (&atomic->value) - 1;
+#endif
 }
 
 /**
@@ -3467,9 +3471,13 @@ _dbus_atomic_inc (DBusAtomic *atomic)
 dbus_int32_t
 _dbus_atomic_dec (DBusAtomic *atomic)
 {
-  // +/- 1 is needed here!
-  // no volatile argument with mingw
+#ifdef HAVE_STDATOMIC_H
+  /* Atomic version of "old = *atomic; *atomic -= 1; return old" */
+  return atomic_fetch_sub (&atomic->value, 1);
+#else
+  /* Atomic version of "*atomic -= 1; return *atomic + 1" */
   return InterlockedDecrement (&atomic->value) + 1;
+#endif
 }
 
 /**
@@ -3482,6 +3490,10 @@ _dbus_atomic_dec (DBusAtomic *atomic)
 dbus_int32_t
 _dbus_atomic_get (DBusAtomic *atomic)
 {
+#ifdef HAVE_STDATOMIC_H
+  /* Atomic version of "return *atomic" */
+  return atomic_load (&atomic->value);
+#else
   /* In this situation, GLib issues a MemoryBarrier() and then returns
    * atomic->value. However, mingw from mingw.org (not to be confused with
    * mingw-w64 from mingw-w64.sf.net) does not have MemoryBarrier in its
@@ -3495,6 +3507,7 @@ _dbus_atomic_get (DBusAtomic *atomic)
   InterlockedExchange (&dummy, 1);
 
   return atomic->value;
+#endif
 }
 
 /**
@@ -3505,7 +3518,12 @@ _dbus_atomic_get (DBusAtomic *atomic)
 void
 _dbus_atomic_set_zero (DBusAtomic *atomic)
 {
+#ifdef HAVE_STDATOMIC_H
+  /* Atomic version of "*atomic = 0" */
+  atomic_store (&atomic->value, 0);
+#else
   InterlockedExchange (&atomic->value, 0);
+#endif
 }
 
 /**
@@ -3516,7 +3534,12 @@ _dbus_atomic_set_zero (DBusAtomic *atomic)
 void
 _dbus_atomic_set_nonzero (DBusAtomic *atomic)
 {
+#ifdef HAVE_STDATOMIC_H
+  /* Atomic version of "*atomic = 1" */
+  atomic_store (&atomic->value, 1);
+#else
   InterlockedExchange (&atomic->value, 1);
+#endif
 }
 
 /**

dbus/dbus-sysdeps-win.h

@@ -87,9 +87,6 @@ _dbus_win_sid_to_name_and_domain (dbus_uid_t uid,
 DBUS_PRIVATE_EXPORT
 dbus_bool_t _dbus_get_install_root (DBusString *str);
 
-void        _dbus_threads_windows_init_global (void);
-void        _dbus_threads_windows_ensure_ctor_linked (void);
-
 DBUS_PRIVATE_EXPORT
 dbus_bool_t _dbus_getsid(char **sid, dbus_pid_t process_id);
 

dbus/dbus-sysdeps.h

@@ -38,6 +38,10 @@
 #include <inttypes.h>
 #endif
 
+#ifdef HAVE_STDATOMIC_H
+#include <stdatomic.h>
+#endif
+
 #include <dbus/dbus-errors.h>
 #include <dbus/dbus-file.h>
 #include <dbus/dbus-string.h>
@@ -333,7 +337,9 @@ typedef struct DBusAtomic DBusAtomic;
  */
 struct DBusAtomic
 {
-#ifdef DBUS_WIN
+#ifdef HAVE_STDATOMIC_H
+  atomic_int value; /**< Value of the atomic integer. */
+#elif defined(DBUS_WIN)
   volatile long value; /**< Value of the atomic integer. */
 #else
   volatile dbus_int32_t value; /**< Value of the atomic integer. */

meson.build

@@ -691,6 +691,7 @@ check_headers = [
     'linux/magic.h',
     'locale.h',
     'signal.h',
+    'stdatomic.h',
     'syslog.h',
     'sys/prctl.h',
     'sys/random.h',