linux-kernel - [PATCH 2/5] kheaders: optimize md5sum calculation for in-tree builds

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Message-Id: <20191008120556.4263-2-yamada.masahiro@socionext.com>
Date:   Tue,  8 Oct 2019 21:05:53 +0900
From:   Masahiro Yamada <yamada.masahiro@...ionext.com>
To:     linux-kbuild@...r.kernel.org
Cc:     Greg KH <gregkh@...uxfoundation.org>,
        Joel Fernandes <joel@...lfernandes.org>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH 2/5] kheaders: optimize md5sum calculation for in-tree builds

This script computes md5sum of headers in srctree and in objtree.
However, when we are building in-tree, we know the srctree and the
objtree are the same. That is, we end up with the same computation
twice. In fact, the first two lines of kernel/kheaders.md5 are always
the same for in-tree builds.

Unify the two md5sum calculations.

For in-tree builds ($building_out_of_srctree is empty), we check
only two directories, include, and arch/$SRCARCH/include.

For out-of-tree builds ($building_out_of_srctree is 1), we check
4 directories, $srctree/include, $srctree/arch/$SRCARCH/include,
include, and arch/$SRCARCH/include since we know they are all
different.

Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>
---

 kernel/gen_kheaders.sh | 32 ++++++++++++++++----------------
 1 file changed, 16 insertions(+), 16 deletions(-)

diff --git a/kernel/gen_kheaders.sh b/kernel/gen_kheaders.sh
index 8aa6d3c37ba7..5f8e664977f8 100755
--- a/kernel/gen_kheaders.sh
+++ b/kernel/gen_kheaders.sh
@@ -21,29 +21,30 @@ arch/$SRCARCH/include/
 # Uncomment it for debugging.
 # if [ ! -f /tmp/iter ]; then iter=1; echo 1 > /tmp/iter;
 # else iter=$(($(cat /tmp/iter) + 1)); echo $iter > /tmp/iter; fi
-# find $src_file_list -name "*.h" | xargs ls -l > /tmp/src-ls-$iter
-# find $obj_file_list -name "*.h" | xargs ls -l > /tmp/obj-ls-$iter
+# find $all_dirs -name "*.h" | xargs ls -l > /tmp/ls-$iter
+
+all_dirs=
+if [ "$building_out_of_srctree" ]; then
+	for d in $dir_list; do
+		all_dirs="$all_dirs $srctree/$d"
+	done
+fi
+all_dirs="$all_dirs $dir_list"
 
 # include/generated/compile.h is ignored because it is touched even when none
 # of the source files changed. This causes pointless regeneration, so let us
 # ignore them for md5 calculation.
-pushd $srctree > /dev/null
-src_files_md5="$(find $dir_list -name "*.h"			   |
-		grep -v "include/generated/compile.h"		   |
-		grep -v "include/generated/autoconf.h"		   |
-		xargs ls -l | md5sum | cut -d ' ' -f1)"
-popd > /dev/null
-obj_files_md5="$(find $dir_list -name "*.h"			   |
-		grep -v "include/generated/compile.h"		   |
-		grep -v "include/generated/autoconf.h"		   |
+headers_md5="$(find $all_dirs -name "*.h"			|
+		grep -v "include/generated/compile.h"	|
+		grep -v "include/generated/autoconf.h"	|
 		xargs ls -l | md5sum | cut -d ' ' -f1)"
+
 # Any changes to this script will also cause a rebuild of the archive.
 this_file_md5="$(ls -l $sfile | md5sum | cut -d ' ' -f1)"
 if [ -f $tarfile ]; then tarfile_md5="$(md5sum $tarfile | cut -d ' ' -f1)"; fi
 if [ -f kernel/kheaders.md5 ] &&
-	[ "$(head -n 1 kernel/kheaders.md5)" = "$src_files_md5" ] &&
-	[ "$(head -n 2 kernel/kheaders.md5 | tail -n 1)" = "$obj_files_md5" ] &&
-	[ "$(head -n 3 kernel/kheaders.md5 | tail -n 1)" = "$this_file_md5" ] &&
+	[ "$(head -n 1 kernel/kheaders.md5)" = "$headers_md5" ] &&
+	[ "$(head -n 2 kernel/kheaders.md5 | tail -n 1)" = "$this_file_md5" ] &&
 	[ "$(tail -n 1 kernel/kheaders.md5)" = "$tarfile_md5" ]; then
 		exit
 fi
@@ -76,8 +77,7 @@ tar "${KBUILD_BUILD_TIMESTAMP:+--mtime=$KBUILD_BUILD_TIMESTAMP}" \
     --owner=0 --group=0 --sort=name --numeric-owner \
     -Jcf $tarfile -C $cpio_dir/ . > /dev/null
 
-echo "$src_files_md5" >  kernel/kheaders.md5
-echo "$obj_files_md5" >> kernel/kheaders.md5
+echo $headers_md5 > kernel/kheaders.md5
 echo "$this_file_md5" >> kernel/kheaders.md5
 echo "$(md5sum $tarfile | cut -d ' ' -f1)" >> kernel/kheaders.md5
 
-- 
2.17.1