Subject: Re: [PATCH net-next v2 00/10] make drivers/net/ethernet W=1 clean

From: Andrew Lunn <[email-masked]>
Date: Tue, 15 Sep 2020 22:43:59 +0200

> Yes we can have our own gcc options in the Makfile regardless of what
> you put in W command line argument.
> 
> Example:
> 
> KBUILD_CFLAGS += -Wextra -Wunused -Wno-unused-parameter
> KBUILD_CFLAGS += -Wmissing-declarations
> KBUILD_CFLAGS += -Wmissing-format-attribute
> KBUILD_CFLAGS += -Wmissing-prototypes
> KBUILD_CFLAGS += -Wold-style-definition
> KBUILD_CFLAGS += -Wmissing-include-dirs

How about something like this, so we get whatever W=1 means.

    Andrew

diff --git a/drivers/net/Makefile b/drivers/net/Makefile
index 72e18d505d1a..d4e125831d1c 100644
--- a/drivers/net/Makefile
+++ b/drivers/net/Makefile
@@ -3,6 +3,9 @@
 # Makefile for the Linux network device drivers.
 #
 
+# Enable W=1 by default
+subdir-ccflags-y := $(KBUILD_CFLAGS_WARN1)
+
 #
 # Networking Core Drivers
 #
diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn
index 95e4cdb94fe9..bf0de3502849 100644
--- a/scripts/Makefile.extrawarn
+++ b/scripts/Makefile.extrawarn
@@ -20,23 +20,26 @@ export KBUILD_EXTRA_WARN
 #
 # W=1 - warnings which may be relevant and do not occur too often
 #
-ifneq ($(findstring 1, $(KBUILD_EXTRA_WARN)),)
-
-KBUILD_CFLAGS += -Wextra -Wunused -Wno-unused-parameter
-KBUILD_CFLAGS += -Wmissing-declarations
-KBUILD_CFLAGS += -Wmissing-format-attribute
-KBUILD_CFLAGS += -Wmissing-prototypes
-KBUILD_CFLAGS += -Wold-style-definition
-KBUILD_CFLAGS += -Wmissing-include-dirs
-KBUILD_CFLAGS += $(call cc-option, -Wunused-but-set-variable)
-KBUILD_CFLAGS += $(call cc-option, -Wunused-const-variable)
-KBUILD_CFLAGS += $(call cc-option, -Wpacked-not-aligned)
-KBUILD_CFLAGS += $(call cc-option, -Wstringop-truncation)
+KBUILD_CFLAGS_WARN1 += -Wextra -Wunused -Wno-unused-parameter
+KBUILD_CFLAGS_WARN1 += -Wmissing-declarations
+KBUILD_CFLAGS_WARN1 += -Wmissing-format-attribute
+KBUILD_CFLAGS_WARN1 += -Wmissing-prototypes
+KBUILD_CFLAGS_WARN1 += -Wold-style-definition
+KBUILD_CFLAGS_WARN1 += -Wmissing-include-dirs
+KBUILD_CFLAGS_WARN1 += $(call cc-option, -Wunused-but-set-variable)
+KBUILD_CFLAGS_WARN1 += $(call cc-option, -Wunused-const-variable)
+KBUILD_CFLAGS_WARN1 += $(call cc-option, -Wpacked-not-aligned)
+KBUILD_CFLAGS_WARN1 += $(call cc-option, -Wstringop-truncation)
 # The following turn off the warnings enabled by -Wextra
-KBUILD_CFLAGS += -Wno-missing-field-initializers
-KBUILD_CFLAGS += -Wno-sign-compare
-KBUILD_CFLAGS += -Wno-type-limits
+KBUILD_CFLAGS_WARN1 += -Wno-missing-field-initializers
+KBUILD_CFLAGS_WARN1 += -Wno-sign-compare
+KBUILD_CFLAGS_WARN1 += -Wno-type-limits
+
+export KBUILD_CFLAGS_WARN1
+
+ifneq ($(findstring 1, $(KBUILD_EXTRA_WARN)),)
 
+KBUILD_CFLAGS += $(KBUILD_CFLAGS_WARN1)
 KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN1
 
 else