From 97fd6a07c2c2fd1d27fc79938eb1a451c92fbfc4 Mon Sep 17 00:00:00 2001
From: Brian Behlendorf <behlendorf1@llnl.gov>
Date: Mon, 19 Sep 2011 13:35:03 -0700
Subject: [PATCH] Fix HAVE_FS_STRUCT_SPINLOCK check for gcc-4.1.2

Older versions of gcc (gcc-4.1.2) will treat an 'incompatible
pointer type' as a warning instead of an error.  This results
in HAVE_FS_STRUCT_SPINLOCK being defined incorrectly.  This
failure mode was observed when using a RHEL6 2.6.32 based kernel
under RHEL5.5 which contains the old version of gcc.  To resolve
the issue the warning is explicitly promoted to an error.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
---
 config/spl-build.m4 | 3 +++
 configure           | 6 ++++++
 2 files changed, 9 insertions(+)

diff --git a/config/spl-build.m4 b/config/spl-build.m4
index f4652bce12f5..c046db830c54 100644
--- a/config/spl-build.m4
+++ b/config/spl-build.m4
@@ -1598,6 +1598,8 @@ dnl # a spinlock_t to improve the fastpath performance.
 dnl #
 AC_DEFUN([SPL_AC_FS_STRUCT_SPINLOCK], [
 	AC_MSG_CHECKING([whether struct fs_struct uses spinlock_t])
+	tmp_flags="$EXTRA_KCFLAGS"
+	EXTRA_KCFLAGS="-Werror"
 	SPL_LINUX_TRY_COMPILE([
 		#include <linux/sched.h>
 		#include <linux/fs_struct.h>
@@ -1611,6 +1613,7 @@ AC_DEFUN([SPL_AC_FS_STRUCT_SPINLOCK], [
 	],[
 		AC_MSG_RESULT(no)
 	])
+	EXTRA_KCFLAGS="$tmp_flags"
 ])
 
 dnl #
diff --git a/configure b/configure
index 72bef74a38e3..1369ca05d96f 100755
--- a/configure
+++ b/configure
@@ -15069,6 +15069,8 @@ fi
 
 	{ $as_echo "$as_me:$LINENO: checking whether struct fs_struct uses spinlock_t" >&5
 $as_echo_n "checking whether struct fs_struct uses spinlock_t... " >&6; }
+	tmp_flags="$EXTRA_KCFLAGS"
+	EXTRA_KCFLAGS="-Werror"
 
 
 cat confdefs.h - <<_ACEOF >conftest.c
@@ -15132,6 +15134,7 @@ fi
 	rm -Rf build
 
 
+	EXTRA_KCFLAGS="$tmp_flags"
 
 
 	{ $as_echo "$as_me:$LINENO: checking whether struct cred exists" >&5
@@ -19267,6 +19270,8 @@ fi
 
 	{ $as_echo "$as_me:$LINENO: checking whether struct fs_struct uses spinlock_t" >&5
 $as_echo_n "checking whether struct fs_struct uses spinlock_t... " >&6; }
+	tmp_flags="$EXTRA_KCFLAGS"
+	EXTRA_KCFLAGS="-Werror"
 
 
 cat confdefs.h - <<_ACEOF >conftest.c
@@ -19330,6 +19335,7 @@ fi
 	rm -Rf build
 
 
+	EXTRA_KCFLAGS="$tmp_flags"
 
 
 	{ $as_echo "$as_me:$LINENO: checking whether struct cred exists" >&5