[PATCH] kbuild: strip the last slash in KBUILD_EXTMOD

From: Wei Yang
Date: Wed Feb 22 2017 - 10:09:07 EST

Current kbuild will build the target again if we run "make M=dir" and "make
M=dir/" by turns, since if_changed will see the prerequisite is changed.
The behavior may confuse the user a little, since actually we are building
the same target and no difference.

According to current implementation in scripts/Makefile.build, the obj
passed to next level is a directory name with last slash stripped. This
patch strips the last slash in KBUILD_EXTMOD which is assigned from "M=".

Signed-off-by: Wei Yang <richard.weiyang@xxxxxxxxx>
Makefile | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/Makefile b/Makefile
index b1037774e8e8..db6ed60928ab 100644
--- a/Makefile
+++ b/Makefile
@@ -184,13 +184,15 @@ endif
# Old syntax make ... SUBDIRS=$PWD is still supported
# Setting the environment variable KBUILD_EXTMOD take precedence

ifeq ("$(origin M)", "command line")

+KBUILD_EXTMOD = $(patsubst %/,%,$(__KBUILD_EXTMOD))
# If building an external module we do not care about the all: rule
# but instead _all depend on modules
PHONY += all