tools: Correct PTHREAD options in config/StdGNU.mk

It is not correct to say -lpthread.  The correct option is -pthread,
which may have sundry other effects on code generation etc.  It needs
to be passed both to compilation and linking.

Fix the configure test to test -pthread, and plumb the resulting flag
through to PTHREAD_{CFLAGS,LDFLAGS} in Tools.mk; also substitute
PTHREAD_LIBS (although this will currently always be empty).
Remove PTHREAD_LIBS setting from StdGNU.mk.

Fix the one user (libxc) to use PTHREAD_{CFLAGS,LDFLAGS} too.

There are still some other users in tree which pass -pthread or
-lpthread by adding it as a literal to their own compiler options.
These will be fixed in a later patch.

Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Roger Pau Monne <roger.pau@entel.upc.edu>
Acked-by: Roger Pau Monne <roger.pau@entel.upc.edu>
Committed-by: Ian Jackson <Ian.Jackson@eu.citrix.com>

7 files changed, 130 insertions, 32 deletions

diff --git a/config/StdGNU.mk b/config/StdGNU.mk
index e2c9335db4..e2f2e1ef36 100644
--- a/config/StdGNU.mk
+++ b/config/StdGNU.mk
@@ -67,7 +67,6 @@ XEN_CONFIG_DIR = $(CONFIG_DIR)/xen
 XEN_SCRIPT_DIR = $(XEN_CONFIG_DIR)/scripts
 
 SOCKET_LIBS =
-PTHREAD_LIBS = -lpthread
 UTIL_LIBS = -lutil
 DLOPEN_LIBS = -ldl
 
diff --git a/config/Tools.mk.in b/config/Tools.mk.in
index 339a7b6f7b..912d02199a 100644
--- a/config/Tools.mk.in
+++ b/config/Tools.mk.in
@@ -26,6 +26,10 @@ PREPEND_LIB         := @PREPEND_LIB@
 APPEND_INCLUDES     := @APPEND_INCLUDES@
 APPEND_LIB          := @APPEND_LIB@
 
+PTHREAD_CFLAGS      := @PTHREAD_CFLAGS@
+PTHREAD_LDFLAGS     := @PTHREAD_LDFLAGS@
+PTHREAD_LIBS        := @PTHREAD_LIBS@
+
 # Download GIT repositories via HTTP or GIT's own protocol?
 # GIT's protocol is faster and more robust, when it works at all (firewalls
 # may block it). We make it the default, but if your GIT repository downloads
diff --git a/tools/configure b/tools/configure
index 64b7eb5425..86618f5dae 100755
--- a/tools/configure
+++ b/tools/configure
@@ -602,6 +602,9 @@ POW_LIB
 LIBOBJS
 ALLOCA
 libiconv
+PTHREAD_LIBS
+PTHREAD_LDFLAGS
+PTHREAD_CFLAGS
 libgcrypt
 libext2fs
 system_aio
@@ -3861,6 +3864,9 @@ case $host_os in *\ *) host_os=`echo "$host_os" | sed 's/ /-/g'`;; esac
 
 
 
+
+
+
 # pkg.m4 - Macros to locate and utilise pkg-config.            -*- Autoconf -*-
 # serial 1 (pkg-config-0.24)
 #
@@ -3924,6 +3930,22 @@ case $host_os in *\ *) host_os=`echo "$host_os" | sed 's/ /-/g'`;; esac
 
 
 
+# We define, separately, PTHREAD_CFLAGS, _LDFLAGS and _LIBS
+# even though currently we don't set them very separately.
+# This means that the makefiles will not need to change in
+# the future if we make the test more sophisticated.
+
+
+
+# We invoke AX_PTHREAD_VARS with the name of another macro
+# which is then expanded once for each variable.
+
+
+
+
+
+
+
 
 # Enable/disable options
 
@@ -7228,47 +7250,70 @@ else
 fi
 
 
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for pthread_create in -lpthread" >&5
-$as_echo_n "checking for pthread_create in -lpthread... " >&6; }
-if test "${ac_cv_lib_pthread_pthread_create+set}" = set; then :
+
+    { $as_echo "$as_me:${as_lineno-$LINENO}: checking for pthread flag" >&5
+$as_echo_n "checking for pthread flag... " >&6; }
+if test "${ax_cv_pthread_flags+set}" = set; then :
   $as_echo_n "(cached) " >&6
 else
-  ac_check_lib_save_LIBS=$LIBS
-LIBS="-lpthread  $LIBS"
-cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+
+        ax_cv_pthread_flags=-pthread
+
+    PTHREAD_CFLAGS="$ax_cv_pthread_flags"
+    PTHREAD_LDFLAGS="$ax_cv_pthread_flags"
+    PTHREAD_LIBS=""
+
+
+    saved_CFLAGS="$CFLAGS"
+
+    saved_LDFLAGS="$LDFLAGS"
+
+    saved_LIBS="$LIBS"
+
+
+    CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
+
+    LDFLAGS="$LDFLAGS $PTHREAD_LDFLAGS"
+
+    LIBS="$LIBS $PTHREAD_LIBS"
+
+        cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
-/* Override any GCC internal prototype to avoid an error.
-   Use char because int might match the return type of a GCC
-   builtin and then its argument prototype would still apply.  */
-#ifdef __cplusplus
-extern "C"
-#endif
-char pthread_create ();
-int
-main ()
-{
-return pthread_create ();
-  ;
-  return 0;
+#include <pthread.h>
+int main(void) {
+  pthread_atfork(0,0,0);
+  pthread_create(0,0,0,0);
 }
+
 _ACEOF
 if ac_fn_c_try_link "$LINENO"; then :
-  ac_cv_lib_pthread_pthread_create=yes
+
 else
-  ac_cv_lib_pthread_pthread_create=no
+  ax_cv_pthread_flags=failed
 fi
 rm -f core conftest.err conftest.$ac_objext \
     conftest$ac_exeext conftest.$ac_ext
-LIBS=$ac_check_lib_save_LIBS
-fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_pthread_pthread_create" >&5
-$as_echo "$ac_cv_lib_pthread_pthread_create" >&6; }
-if test "x$ac_cv_lib_pthread_pthread_create" = x""yes; then :
 
-else
-  as_fn_error $? "Could not find libpthread" "$LINENO" 5
+    CFLAGS="$saved_CFLAGS"
+
+    LDFLAGS="$saved_LDFLAGS"
+
+    LIBS="$saved_LIBS"
+
+
 fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ax_cv_pthread_flags" >&5
+$as_echo "$ax_cv_pthread_flags" >&6; }
+    if test "x$ax_cv_pthread_flags" = xfailed; then
+        as_fn_error $? "-pthread does not work" "$LINENO" 5
+    fi
+
+    PTHREAD_CFLAGS="$ax_cv_pthread_flags"
+    PTHREAD_LDFLAGS="$ax_cv_pthread_flags"
+    PTHREAD_LIBS=""
+
+
 
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for clock_gettime in -lrt" >&5
 $as_echo_n "checking for clock_gettime in -lrt... " >&6; }
diff --git a/tools/configure.ac b/tools/configure.ac
index 0204e36449..250dffdf47 100644
--- a/tools/configure.ac
+++ b/tools/configure.ac
@@ -23,6 +23,7 @@ AC_USE_SYSTEM_EXTENSIONS
 AC_CANONICAL_HOST
 
 # M4 Macro includes
+m4_include([m4/savevar.m4])
 m4_include([m4/features.m4])
 m4_include([m4/path_or_fail.m4])
 m4_include([m4/python_version.m4])
@@ -33,6 +34,7 @@ m4_include([m4/set_cflags_ldflags.m4])
 m4_include([m4/uuid.m4])
 m4_include([m4/pkg.m4])
 m4_include([m4/curses.m4])
+m4_include([m4/pthread.m4])
 
 # Enable/disable options
 AX_ARG_DEFAULT_DISABLE([githttp], [Download GIT repositories via HTTP])
@@ -129,8 +131,7 @@ AC_CHECK_LIB([ext2fs], [ext2fs_open2], [libext2fs="y"], [libext2fs="n"])
 AC_SUBST(libext2fs)
 AC_CHECK_LIB([gcrypt], [gcry_md_hash_buffer], [libgcrypt="y"], [libgcrypt="n"])
 AC_SUBST(libgcrypt)
-AC_CHECK_LIB([pthread], [pthread_create], [] ,
-    [AC_MSG_ERROR([Could not find libpthread])])
+AX_CHECK_PTHREAD
 AC_CHECK_LIB([rt], [clock_gettime])
 AC_CHECK_LIB([yajl], [yajl_alloc], [],
     [AC_MSG_ERROR([Could not find yajl])])
diff --git a/tools/libxc/Makefile b/tools/libxc/Makefile
index 55eb755059..a1ba13402b 100644
--- a/tools/libxc/Makefile
+++ b/tools/libxc/Makefile
@@ -73,6 +73,8 @@ CFLAGS   += -I. $(CFLAGS_xeninclude)
 # Needed for posix_fadvise64() in xc_linux.c
 CFLAGS-$(CONFIG_Linux) += -D_GNU_SOURCE
 
+CFLAGS	+= $(PTHREAD_CFLAGS)
+
 # Define this to make it possible to run valgrind on code linked with these
 # libraries.
 #CFLAGS   += -DVALGRIND -O0 -ggdb3
@@ -157,7 +159,7 @@ libxenctrl.so.$(MAJOR): libxenctrl.so.$(MAJOR).$(MINOR)
 	ln -sf $< $@
 
 libxenctrl.so.$(MAJOR).$(MINOR): $(CTRL_PIC_OBJS)
-	$(CC) $(LDFLAGS) -Wl,$(SONAME_LDFLAG) -Wl,libxenctrl.so.$(MAJOR) $(SHLIB_LDFLAGS) -o $@ $^ $(DLOPEN_LIBS) $(PTHREAD_LIBS) $(APPEND_LDFLAGS)
+	$(CC) $(LDFLAGS) $(PTHREAD_LDFLAGS) -Wl,$(SONAME_LDFLAG) -Wl,libxenctrl.so.$(MAJOR) $(SHLIB_LDFLAGS) -o $@ $^ $(DLOPEN_LIBS) $(PTHREAD_LIBS) $(APPEND_LDFLAGS)
 
 # libxenguest
 
diff --git a/tools/m4/pthread.m4 b/tools/m4/pthread.m4
new file mode 100644
index 0000000000..57ea85c1f9
--- /dev/null
+++ b/tools/m4/pthread.m4
@@ -0,0 +1,41 @@
+# We define, separately, PTHREAD_CFLAGS, _LDFLAGS and _LIBS
+# even though currently we don't set them very separately.
+# This means that the makefiles will not need to change in
+# the future if we make the test more sophisticated.
+
+AC_DEFUN([AX_PTHREAD_CV2VARS],[
+    PTHREAD_CFLAGS="$ax_cv_pthread_flags"
+    PTHREAD_LDFLAGS="$ax_cv_pthread_flags"
+    PTHREAD_LIBS=""
+])
+
+# We invoke AX_PTHREAD_VARS with the name of another macro
+# which is then expanded once for each variable.
+AC_DEFUN([AX_PTHREAD_VARS],[$1(CFLAGS) $1(LDFLAGS) $1(LIBS)])
+
+AC_DEFUN([AX_PTHREAD_VAR_APPLY],[
+    $1="$$1 $PTHREAD_$1"
+])
+AC_DEFUN([AX_PTHREAD_VAR_SUBST],[AC_SUBST(PTHREAD_$1)])
+
+AC_DEFUN([AX_CHECK_PTHREAD],[
+    AC_CACHE_CHECK([for pthread flag], [ax_cv_pthread_flags], [
+        ax_cv_pthread_flags=-pthread
+        AX_PTHREAD_CV2VARS
+        AX_PTHREAD_VARS([AX_SAVEVAR_SAVE])
+        AX_PTHREAD_VARS([AX_PTHREAD_VAR_APPLY])
+        AC_LINK_IFELSE([
+#include <pthread.h>
+int main(void) {
+  pthread_atfork(0,0,0);
+  pthread_create(0,0,0,0);
+}
+],[],[ax_cv_pthread_flags=failed])
+        AX_PTHREAD_VARS([AX_SAVEVAR_RESTORE])
+    ])
+    if test "x$ax_cv_pthread_flags" = xfailed; then
+        AC_MSG_ERROR([-pthread does not work])
+    fi
+    AX_PTHREAD_CV2VARS
+    AX_PTHREAD_VARS([AX_PTHREAD_VAR_SUBST])
+])
diff --git a/tools/m4/savevar.m4 b/tools/m4/savevar.m4
new file mode 100644
index 0000000000..2156beed17
--- /dev/null
+++ b/tools/m4/savevar.m4
@@ -0,0 +1,6 @@
+AC_DEFUN([AX_SAVEVAR_SAVE],[
+    saved_$1="$$1"
+])
+AC_DEFUN([AX_SAVEVAR_RESTORE],[
+    $1="$saved_$1"
+])