+ ])
+
+ ZFS_AC_KERNEL_CONFIG_PREEMPT
+ ZFS_AC_KERNEL_CONFIG_DEBUG_LOCK_ALLOC
+])
+
+dnl #
+dnl # Check CONFIG_PREEMPT
+dnl #
+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_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.]), [])
+])
+
+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 and will prevent the module linking stage
+ *** from succeeding. You must rebuild your kernel without this
+ *** option enabled.])
+ ])
+ EXTRA_KCFLAGS="$tmp_flags"
+ ], [])