This is a note to let you know that I've just added the patch titled kbuild: remove trailing slashes from $(KBUILD_EXTMOD) to the 5.13-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: kbuild-remove-trailing-slashes-from-kbuild_extmod.patch and it can be found in the queue-5.13 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit cbb4600303d10e74b981dfd478aee3f30068bc38 Author: Masahiro Yamada <masahiroy@xxxxxxxxxx> Date: Wed Jun 2 23:02:13 2021 +0900 kbuild: remove trailing slashes from $(KBUILD_EXTMOD) [ Upstream commit 74ee585b7eecd98be3650e677625a0ee588d08e0 ] M= (or KBUILD_EXTMOD) generally expects a directory path without any trailing slashes, like M=a/b/c. If you add a trailing slash, like M=a/b/c/, you will get ugly build logs (two slashes in a series), but it still works fine as long as it is consistent between 'make modules' and 'make modules_install'. The following commands correctly build and install the modules. $ make M=a/b/c/ modules $ sudo make M=a/b/c/ modules_install Since commit ccae4cfa7bfb ("kbuild: refactor scripts/Makefile.modinst"), a problem happens if you add a trailing slash only for modules_install. $ make M=a/b/c modules $ sudo make M=a/b/c/ modules_install No module is installed in this case, Johannes Berg reported. [1] Trim any trailing slashes from $(KBUILD_EXTMOD). I used the 'dirname' command to remove all the trailing slashes in case someone adds more slashes like M=a/b/c/////. The Make's built-in function, $(dir ...) cannot take care of such a case. [1]: https://lore.kernel.org/lkml/10cc8522b27a051e6a9c3e158a4c4b6414fd04a0.camel@xxxxxxxxxxxxxxxx/ Fixes: ccae4cfa7bfb ("kbuild: refactor scripts/Makefile.modinst") Reported-by: Johannes Berg <johannes@xxxxxxxxxxxxxxxx> Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/Makefile b/Makefile index 83f4212e004f..4258a60f6119 100644 --- a/Makefile +++ b/Makefile @@ -129,6 +129,11 @@ endif $(if $(word 2, $(KBUILD_EXTMOD)), \ $(error building multiple external modules is not supported)) +# Remove trailing slashes +ifneq ($(filter %/, $(KBUILD_EXTMOD)),) +KBUILD_EXTMOD := $(shell dirname $(KBUILD_EXTMOD).) +endif + export KBUILD_EXTMOD # Kbuild will save output files in the current working directory.