On Sun, Sep 20, 2020 at 12:42:51PM +0900, Masahiro Yamada wrote: > On Sun, Sep 20, 2020 at 4:03 AM Andrew Lunn <andrew@xxxxxxx> wrote: > > > > There is a movement to make the code base compile clean with W=1. Some > > subsystems are already clean. In order to keep them clean, we need > > developers to build new code with W=1 by default in these subsystems. > > > > This patchset refactors the core Makefile warning code to allow the > > additional warnings W=1 adds available to any Makefile. The Ethernet > > PHY subsystem Makefiles then make use of this to make W=1 the default > > for this subsystem. > > > > RFT since i've only tested with x86 and arm with a modern gcc. Is the > > code really clean for older compilers? For clang? > > > I appreciate your efforts for keeping your subsystems > clean for W=1 builds, and I hope this work will be > extended towards upper directory level, > drivers/net/phy -> drivers/net -> drivers/. It definitely is. drivers/net: https://www.spinics.net/lists/netdev/msg683687.html drivers/spi https://www.spinics.net/lists/linux-spi/msg23280.html drivers/mfd https://www.mail-archive.com/linux-kernel@xxxxxxxxxxxxxxx/msg2211644.html etc. > So, another idea might be hard-coding extra warnings > like drivers/gpu/drm/i915/Makefile. > > For example, your subsystem already achieved > -Wmissing-declarations free. > > You can add > > subdir-ccflags-y += -Wmissing-declarations > > to drivers/net/phy/Makefile. > > Once you fix all net drivers, you can move it to > the parent, drivers/net/Makefile. > > Then, drivers/Makefile next, and if it reaches > the top directory level, we can move it to W=0. Do you think this will scale? Lets just assume we do this at driver/ level. We have 141 subdirectories in driver/ . So we will end up with 141 subdir-ccflags-y += lines which we need to maintain. Given the current cleanup effort, many are going to be identical to todays W=1. How do we maintain those 141 lines when it is time to add a new flag to W=1? How often are new W=1 flags added? My patch exported KBUILD_CFLAGS_WARN1. How about instead we export KBUILD_CFLAGS_WARN1_20200920. A subsystem can then sign up to being W=1 clean as for the 20200920 definition of W=1. If you want to add a new warning KBUILD_CFLAGS_WARN1_20201031 := KBUILD_CFLAGS_WARN1_20200920 + "-Wghosts" W=1 will always use the latest. You then build with W=1, maybe by throwing it at 0-day, find which subsystems are still clean, and update their subdir-ccflags-y += line with the new timestamp? This should help with scaling, in that a subsystem is not dealing with a list of warnings, just a symbol that represents the warnings from a particular date? Or maybe others have better ideas? Andrew
