[PATCH tip/core/rcu 2/2] kconfig: make setlocalversion -dirty check optional

["Paul E. McKenney" <paulmck@linux.vnet.ibm.com>]

The git commands that check for uncommitted changes can be quite
expensive, so this patch introduces an environment variable named
KBUILD_CONFIG_NO_CHECK_DIRTY to control these checks for git.
If KBUILD_CONFIG_NO_CHECK_DIRTY is unset or is set to an empty
string, the dirty checks are performed (the default).  Otherwise,
KBUILD_CONFIG_NO_CHECK_DIRTY is set to some non-empty string, and the
dirty checks are omitted.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
 scripts/setlocalversion |   17 ++++++++++-------
 1 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/scripts/setlocalversion b/scripts/setlocalversion
index 46989b8..3d4ff84 100755
--- a/scripts/setlocalversion
+++ b/scripts/setlocalversion
@@ -39,13 +39,16 @@ if head=`git rev-parse --verify --short HEAD 2>/dev/null`; then
 	        printf -- '-svn%s' "`git svn find-rev $head`"
 	fi
 
-	# Update index only on r/w media
-	[ -w . ] && git update-index --refresh --unmerged > /dev/null
-
-	# Check for uncommitted changes
-	if git diff-index --name-only HEAD | grep -v "^scripts/package" \
-	    | read dummy; then
-		printf '%s' -dirty
+	if [ -z "$KBUILD_CONFIG_NO_CHECK_DIRTY" ]; then
+		# Update index only on r/w media
+		[ -w . ] && git update-index --refresh --unmerged > /dev/null
+
+		# Check for uncommitted changes
+		if git diff-index --name-only HEAD \
+		    | grep -v "^scripts/package" \
+		    | read dummy; then
+			printf '%s' -dirty
+		fi
 	fi
 
 	# All done with git
-- 
1.6.6