kbuild: support W=e to make build abort in case of warning

When developing new code/feature, CONFIG_WERROR is most
often turned off, especially for people using make W=12 to
get more warnings.

In such case, turning on -Werror temporarily would require
switching on CONFIG_WERROR in the configuration, building,
then switching off CONFIG_WERROR.

For this use case, this patch introduces a new 'e' modifier
to W= as a short hand for KCFLAGS+=-Werror" so that -Werror
got added to the kernel (built-in) and modules' CFLAGS.

Signed-off-by: Yann Droneaud <ydroneaud@opteya.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

diff --git a/Makefile b/Makefile
index e915aacd02b06e0b7c619b312087c2c01098b9ee..235d68fa14700fb47c2f904b9b39955a501634b0 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -1650,6 +1650,7 @@ help:
        @echo  '                1: warnings which may be relevant and do not occur too often'
        @echo  '                2: warnings which occur quite often but may still be relevant'
        @echo  '                3: more obscure warnings, can most likely be ignored'
+       @echo  '                e: warnings are being treated as errors'
        @echo  '                Multiple levels can be combined with W=12 or W=123'
        @echo  ''
        @echo  'Execute "make" or "make all" to build all targets marked with [*] '

diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn
index 650d0b8ceec34b65007640aa5a810763b05d9ba4..f5f0d6f09053f02f8ab22c520e2cf704b365e1f9 100644 (file)
--- a/scripts/Makefile.extrawarn
+++ b/scripts/Makefile.extrawarn
@@ -2,8 +2,8 @@
 # ==========================================================================
 # make W=... settings
 #
-# There are three warning groups enabled by W=1, W=2, W=3.
-# They are independent, and can be combined like W=12 or W=123.
+# There are four warning groups enabled by W=1, W=2, W=3, and W=e
+# They are independent, and can be combined like W=12 or W=123e.
 # ==========================================================================
 
 KBUILD_CFLAGS += $(call cc-disable-warning, packed-not-aligned)
@@ -94,3 +94,12 @@ KBUILD_CFLAGS += $(call cc-option, -Wpacked-bitfield-compat)
 KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN3
 
 endif
+
+#
+# W=e - error out on warnings
+#
+ifneq ($(findstring e, $(KBUILD_EXTRA_WARN)),)
+
+KBUILD_CFLAGS += -Werror
+
+endif