rcutorture: Check initrd/init instead of initrd only

If the build fails, we can end up with an empty initrd directory which
prevents the build script from operating again. Better rely on the
resulting init executable instead.

Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

tools/testing/selftests/rcutorture/bin/mkinitrd.sh

@@ -28,8 +28,8 @@ if [ ! -d "$D" ]; then
     echo >&2 "$D does not exist: Malformed kernel source tree?"
     exit 1
 fi
-if [ -d "$D/initrd" ]; then
-    echo "$D/initrd already exists, no need to create it"
+if [ -s "$D/initrd/init" ]; then
+    echo "$D/initrd/init already exists, no need to create it"
     exit 0
 fi
 
@@ -65,7 +65,7 @@ then
 	# Filesystem creation
 	dracut --force --no-hostonly --no-hostonly-cmdline --module "base" $T/initramfs.img
 	cd $D
-	mkdir initrd
+	mkdir -p initrd
 	cd initrd
 	zcat $T/initramfs.img | cpio -id
 	cp $T/init init
@@ -79,7 +79,7 @@ fi
 # future-proof than dracut.
 echo "Could not find dracut, attempting C initrd"
 cd $D
-mkdir initrd
+mkdir -p initrd
 cd initrd
 cat > init.c << '___EOF___'
 #include <unistd.h>