[PATCH v3] builddeb: parallelize debug module installation

[Chris J Arges]

When building the dbg package, we use a large 'for module in $(find' loop that
can be easily parallelized by using 'find | xargs'. This patch modifies this
loop to use the later paradigm.

In addition, check if the user has requested a parallel build with make. If so,
add the appropriate flags to xargs to set MAXPROCS (-P) equal to the number of
processing units on the system.

Signed-off-by: Chris J Arges <chris.j.arges@xxxxxxxxxxxxx>
---
 scripts/package/builddeb | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/scripts/package/builddeb b/scripts/package/builddeb
index 88dbf23..5849f0c 100755
--- a/scripts/package/builddeb
+++ b/scripts/package/builddeb
@@ -152,16 +152,21 @@ if grep -q '^CONFIG_MODULES=y' $KCONFIG_CONFIG ; then
 		rmdir "$tmpdir/lib/modules/$version"
 	fi
 	if [ -n "$BUILD_DEBUG" ] ; then
-		for module in $(find $tmpdir/lib/modules/ -name *.ko -printf '%P\n'); do
-			module=lib/modules/$module
-			mkdir -p $(dirname $dbg_dir/usr/lib/debug/$module)
+		# If we've invoked make with -j, then parallelize; otherwise
+		# just use a single process.
+		procs=1
+		test "${MAKEFLAGS#*-j}" != "${MAKEFLAGS}" && procs=`getconf _NPROCESSORS_ONLN`
+		find $tmpdir/lib/modules/ -name *.ko -printf '%P\n' | xargs -n1 -P${procs} -I {} sh -c '
+			mkdir -p $(dirname '"$dbg_dir"'/usr/lib/debug/lib/modules/$1);'"
 			# only keep debug symbols in the debug file
-			$OBJCOPY --only-keep-debug $tmpdir/$module $dbg_dir/usr/lib/debug/$module
+			$OBJCOPY --only-keep-debug $tmpdir/lib/modules/{} \
+				$dbg_dir/usr/lib/debug/lib/modules/{};
 			# strip original module from debug symbols
-			$OBJCOPY --strip-debug $tmpdir/$module
+			$OBJCOPY --strip-debug $tmpdir/lib/modules/{};
 			# then add a link to those
-			$OBJCOPY --add-gnu-debuglink=$dbg_dir/usr/lib/debug/$module $tmpdir/$module
-		done
+			$OBJCOPY --add-gnu-debuglink=$dbg_dir/usr/lib/debug/lib/modules/{} \
+				$tmpdir/lib/modules/{};
+		" -- {}
 	fi
 fi
 
-- 
1.9.1

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