Extend CONFIG_DEBUG_LOCK_ALLOC check

The CONFIG_DEBUG_LOCK_ALLOC check at configure time was added to
detect when mutex_lock() is defined as a GPL-only symbol.  However,
the check as written only inferred this from this configuration
setting, it never actually checked.  This change introduces that
missing check to prevent false positives.

Signed-off-by: Brian Behlendorf <[email protected]>

2 files changed, 237 insertions, 59 deletions

diff --git a/config/kernel.m4 b/config/kernel.m4
index 48e92ced4..0f6100071 100644
--- a/config/kernel.m4
+++ b/config/kernel.m4
@@ -311,34 +311,74 @@ dnl # Certain kernel build options are not supported.  These must be
 dnl # detected at configure time and cause a build failure.  Otherwise
 dnl # modules may be successfully built that behave incorrectly.
 dnl #
-dnl # CONFIG_PREEMPT - Preempt kernels require special handling.
+AC_DEFUN([ZFS_AC_KERNEL_CONFIG], [
+
+	AS_IF([test "$ZFS_META_LICENSE" = GPL], [
+		AC_DEFINE([HAVE_GPL_ONLY_SYMBOLS], [1],
+			[Define to 1 if licensed under the GPL])
+	])
+
+	ZFS_AC_KERNEL_CONFIG_PREEMPT
+	ZFS_AC_KERNEL_CONFIG_DEBUG_LOCK_ALLOC
+])
+
 dnl #
-dnl # There are certain kernel build options which when enabled are
-dnl # completely incompatible with non GPL kernel modules.  It is best
-dnl # to detect these at configure time and fail with a clear error
-dnl # rather than build everything and fail during linking.
+dnl # Check CONFIG_PREEMPT
 dnl #
-dnl # CONFIG_DEBUG_LOCK_ALLOC - Maps mutex_lock() to mutex_lock_nested()
+dnl # Premptible kernels will be supported in the future.  But at the
+dnl # moment there are a few places in the code which need to be updated
+dnl # to accomidate them.  Until that work occurs we should detect this
+dnl # at configure time and fail with a sensible message.  Otherwise,
+dnl # people will be able to build successfully, however they will have
+dnl # stability problems.  See https://github.com/zfsonlinux/zfs/issues/83
 dnl #
-AC_DEFUN([ZFS_AC_KERNEL_CONFIG], [
+AC_DEFUN([ZFS_AC_KERNEL_CONFIG_PREEMPT], [
 
 	ZFS_LINUX_CONFIG([PREEMPT],
 		AC_MSG_ERROR([
 	*** Kernel built with CONFIG_PREEMPT which is not supported.
 	*** You must rebuild your kernel without this option.]), [])
+])
 
-	AS_IF([test "$ZFS_META_LICENSE" = CDDL], [
-		ZFS_LINUX_CONFIG([DEBUG_LOCK_ALLOC],
-		AC_MSG_ERROR([
-	*** Kernel built with CONFIG_DEBUG_LOCK_ALLOC which is
-	*** incompatible with the CDDL license.  You must rebuild
-	*** your kernel without this option.]), [])
-	])
-
-	AS_IF([test "$ZFS_META_LICENSE" = GPL], [
-		AC_DEFINE([HAVE_GPL_ONLY_SYMBOLS], [1],
-			[Define to 1 if licensed under the GPL])
-	])
+dnl #
+dnl # Check CONFIG_DEBUG_LOCK_ALLOC
+dnl #
+dnl # This is typically only set for debug kernels because it comes with
+dnl # a performance penalty.  However, when it is set it maps the non-GPL
+dnl # symbol mutex_lock() to the GPL-only mutex_lock_nested() symbol.
+dnl # This will cause a failure at link time which we'd rather know about
+dnl # at compile time.
+dnl #
+dnl # Since we plan to pursue making mutex_lock_nested() a non-GPL symbol
+dnl # with the upstream community we add a check to detect this case.
+dnl #
+AC_DEFUN([ZFS_AC_KERNEL_CONFIG_DEBUG_LOCK_ALLOC], [
+
+	ZFS_LINUX_CONFIG([DEBUG_LOCK_ALLOC], [
+		AC_MSG_CHECKING([whether mutex_lock() is GPL-only])
+		tmp_flags="$EXTRA_KCFLAGS"
+		ZFS_LINUX_TRY_COMPILE([
+			#include <linux/module.h>
+			#include <linux/mutex.h>
+
+			MODULE_LICENSE("$ZFS_META_LICENSE");
+		],[
+			struct mutex lock;
+
+			mutex_init(&lock);
+			mutex_lock(&lock);
+			mutex_unlock(&lock);
+		],[
+			AC_MSG_RESULT(no)
+		],[
+			AC_MSG_RESULT(yes)
+			AC_MSG_ERROR([
+	*** Kernel built with CONFIG_DEBUG_LOCK_ALLOC which is incompatible
+	*** with the CDDL license.  You must rebuild your kernel without
+	*** this option enabled.])
+		])
+		EXTRA_KCFLAGS="$tmp_flags"
+	], [])
 ])
 
 dnl #
diff --git a/configure b/configure
index f891e1aaf..6b198f873 100755
--- a/configure
+++ b/configure
@@ -12396,6 +12396,19 @@ $as_echo "$SPL_SYMBOLS" >&6; }
 
 
 
+	if test "$ZFS_META_LICENSE" = GPL; then
+
+
+cat >>confdefs.h <<\_ACEOF
+#define HAVE_GPL_ONLY_SYMBOLS 1
+_ACEOF
+
+
+fi
+
+
+
+
 	{ $as_echo "$as_me:$LINENO: checking whether Linux was built with CONFIG_PREEMPT" >&5
 $as_echo_n "checking whether Linux was built with CONFIG_PREEMPT... " >&6; }
 
@@ -12466,9 +12479,9 @@ fi
 
 
 
-	if test "$ZFS_META_LICENSE" = CDDL; then
 
-		{ $as_echo "$as_me:$LINENO: checking whether Linux was built with CONFIG_DEBUG_LOCK_ALLOC" >&5
+
+	{ $as_echo "$as_me:$LINENO: checking whether Linux was built with CONFIG_DEBUG_LOCK_ALLOC" >&5
 $as_echo_n "checking whether Linux was built with CONFIG_DEBUG_LOCK_ALLOC... " >&6; }
 
 
@@ -12513,23 +12526,74 @@ _ACEOF
 
 		{ $as_echo "$as_me:$LINENO: result: yes" >&5
 $as_echo "yes" >&6; }
-		{ { $as_echo "$as_me:$LINENO: error:
-	*** Kernel built with CONFIG_DEBUG_LOCK_ALLOC which is
-	*** incompatible with the CDDL license.  You must rebuild
-	*** your kernel without this option." >&5
-$as_echo "$as_me: error:
-	*** Kernel built with CONFIG_DEBUG_LOCK_ALLOC which is
-	*** incompatible with the CDDL license.  You must rebuild
-	*** your kernel without this option." >&2;}
-   { (exit 1); exit 1; }; }
+
+		{ $as_echo "$as_me:$LINENO: checking whether mutex_lock() is GPL-only" >&5
+$as_echo_n "checking whether mutex_lock() is GPL-only... " >&6; }
+		tmp_flags="$EXTRA_KCFLAGS"
+
+
+cat confdefs.h - <<_ACEOF >conftest.c
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+
+			#include <linux/module.h>
+			#include <linux/mutex.h>
+
+			MODULE_LICENSE("$ZFS_META_LICENSE");
+
+int
+main (void)
+{
+
+			struct mutex lock;
+
+			mutex_init(&lock);
+			mutex_lock(&lock);
+			mutex_unlock(&lock);
+
+  ;
+  return 0;
+}
+
+_ACEOF
+
+
+	rm -Rf build && mkdir -p build
+	echo "obj-m := conftest.o" >build/Makefile
+	if { ac_try='cp conftest.c build && make modules -C $LINUX_OBJ EXTRA_CFLAGS="-Werror-implicit-function-declaration $EXTRA_KCFLAGS" $ARCH_UM M=$PWD/build'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  $as_echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } >/dev/null && { ac_try='test -s build/conftest.o'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  $as_echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+
+			{ $as_echo "$as_me:$LINENO: result: no" >&5
+$as_echo "no" >&6; }
 
 else
   $as_echo "$as_me: failed program was:" >&5
 sed 's/^/| /' conftest.$ac_ext >&5
 
-		{ $as_echo "$as_me:$LINENO: result: no" >&5
-$as_echo "no" >&6; }
-
+			{ $as_echo "$as_me:$LINENO: result: yes" >&5
+$as_echo "yes" >&6; }
+			{ { $as_echo "$as_me:$LINENO: error:
+	*** Kernel built with CONFIG_DEBUG_LOCK_ALLOC which is incompatible
+	*** with the CDDL license.  You must rebuild your kernel without
+	*** this option enabled." >&5
+$as_echo "$as_me: error:
+	*** Kernel built with CONFIG_DEBUG_LOCK_ALLOC which is incompatible
+	*** with the CDDL license.  You must rebuild your kernel without
+	*** this option enabled." >&2;}
+   { (exit 1); exit 1; }; }
 
 
 
@@ -12538,21 +12602,26 @@ fi
 	rm -Rf build
 
 
+		EXTRA_KCFLAGS="$tmp_flags"
 
 
-fi
-
+else
+  $as_echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
 
-	if test "$ZFS_META_LICENSE" = GPL; then
+		{ $as_echo "$as_me:$LINENO: result: no" >&5
+$as_echo "no" >&6; }
 
 
-cat >>confdefs.h <<\_ACEOF
-#define HAVE_GPL_ONLY_SYMBOLS 1
-_ACEOF
 
 
 fi
 
+	rm -Rf build
+
+
+
+
 
 
 	{ $as_echo "$as_me:$LINENO: checking block device operation prototypes" >&5
@@ -18420,6 +18489,19 @@ $as_echo "$SPL_SYMBOLS" >&6; }
 
 
 
+	if test "$ZFS_META_LICENSE" = GPL; then
+
+
+cat >>confdefs.h <<\_ACEOF
+#define HAVE_GPL_ONLY_SYMBOLS 1
+_ACEOF
+
+
+fi
+
+
+
+
 	{ $as_echo "$as_me:$LINENO: checking whether Linux was built with CONFIG_PREEMPT" >&5
 $as_echo_n "checking whether Linux was built with CONFIG_PREEMPT... " >&6; }
 
@@ -18490,9 +18572,9 @@ fi
 
 
 
-	if test "$ZFS_META_LICENSE" = CDDL; then
 
-		{ $as_echo "$as_me:$LINENO: checking whether Linux was built with CONFIG_DEBUG_LOCK_ALLOC" >&5
+
+	{ $as_echo "$as_me:$LINENO: checking whether Linux was built with CONFIG_DEBUG_LOCK_ALLOC" >&5
 $as_echo_n "checking whether Linux was built with CONFIG_DEBUG_LOCK_ALLOC... " >&6; }
 
 
@@ -18537,23 +18619,74 @@ _ACEOF
 
 		{ $as_echo "$as_me:$LINENO: result: yes" >&5
 $as_echo "yes" >&6; }
-		{ { $as_echo "$as_me:$LINENO: error:
-	*** Kernel built with CONFIG_DEBUG_LOCK_ALLOC which is
-	*** incompatible with the CDDL license.  You must rebuild
-	*** your kernel without this option." >&5
-$as_echo "$as_me: error:
-	*** Kernel built with CONFIG_DEBUG_LOCK_ALLOC which is
-	*** incompatible with the CDDL license.  You must rebuild
-	*** your kernel without this option." >&2;}
-   { (exit 1); exit 1; }; }
+
+		{ $as_echo "$as_me:$LINENO: checking whether mutex_lock() is GPL-only" >&5
+$as_echo_n "checking whether mutex_lock() is GPL-only... " >&6; }
+		tmp_flags="$EXTRA_KCFLAGS"
+
+
+cat confdefs.h - <<_ACEOF >conftest.c
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+
+			#include <linux/module.h>
+			#include <linux/mutex.h>
+
+			MODULE_LICENSE("$ZFS_META_LICENSE");
+
+int
+main (void)
+{
+
+			struct mutex lock;
+
+			mutex_init(&lock);
+			mutex_lock(&lock);
+			mutex_unlock(&lock);
+
+  ;
+  return 0;
+}
+
+_ACEOF
+
+
+	rm -Rf build && mkdir -p build
+	echo "obj-m := conftest.o" >build/Makefile
+	if { ac_try='cp conftest.c build && make modules -C $LINUX_OBJ EXTRA_CFLAGS="-Werror-implicit-function-declaration $EXTRA_KCFLAGS" $ARCH_UM M=$PWD/build'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  $as_echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } >/dev/null && { ac_try='test -s build/conftest.o'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  $as_echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+
+			{ $as_echo "$as_me:$LINENO: result: no" >&5
+$as_echo "no" >&6; }
 
 else
   $as_echo "$as_me: failed program was:" >&5
 sed 's/^/| /' conftest.$ac_ext >&5
 
-		{ $as_echo "$as_me:$LINENO: result: no" >&5
-$as_echo "no" >&6; }
-
+			{ $as_echo "$as_me:$LINENO: result: yes" >&5
+$as_echo "yes" >&6; }
+			{ { $as_echo "$as_me:$LINENO: error:
+	*** Kernel built with CONFIG_DEBUG_LOCK_ALLOC which is incompatible
+	*** with the CDDL license.  You must rebuild your kernel without
+	*** this option enabled." >&5
+$as_echo "$as_me: error:
+	*** Kernel built with CONFIG_DEBUG_LOCK_ALLOC which is incompatible
+	*** with the CDDL license.  You must rebuild your kernel without
+	*** this option enabled." >&2;}
+   { (exit 1); exit 1; }; }
 
 
 
@@ -18562,21 +18695,26 @@ fi
 	rm -Rf build
 
 
+		EXTRA_KCFLAGS="$tmp_flags"
 
 
-fi
-
+else
+  $as_echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
 
-	if test "$ZFS_META_LICENSE" = GPL; then
+		{ $as_echo "$as_me:$LINENO: result: no" >&5
+$as_echo "no" >&6; }
 
 
-cat >>confdefs.h <<\_ACEOF
-#define HAVE_GPL_ONLY_SYMBOLS 1
-_ACEOF
 
 
 fi
 
+	rm -Rf build
+
+
+
+
 
 
 	{ $as_echo "$as_me:$LINENO: checking block device operation prototypes" >&5