* Sam Ravnborg <sam@xxxxxxxxxxxx> wrote: > We have at several occasions discussed if our header files > should include their dependencies or not. > > But we were lacking a tool to tell us if our header files > included the headerfiles they needed or not. > > headercheck can be used to do so. > > headercheck use the existing Kbuild files in > include/ to determine which directories to visit. > > And for each directory it create one .c file for each > .h file and build it. > > A .c file looks like this: > > $cat module.h.c > #include <linux/module.h> > > > Building this file will tell us if module.h is > missing any dependencies (but NOT if it has too many) with > the current configuration. > > We know that some header files are simply NOT supposed to be included > direct and thus is not eligble to such a check. > > To avoid checking these we can say in Kbuild: > > ignore-y += compiler-gcc.h > > This tells headercheck to ignore compiler-gcc.h when performing > the headercheck. > > The current implementation leaves a lot of .c files. > I will address this if the concept is considered acceptable. > > To visit all relevant directories we need to adjust the Kbuild > files but that can wait until we have the current pile fixed. > Likewise it does not support arch specific include files. > That can wait too. > > I have tried running headercheck on an i386 defconfig and > the result shows that a lot af headers does not include there > dependencies. > > The numbers (including sub-directories): > > 25 include/asm-generic > 12 include/drm > 282 include/linux > 2 include/mtd > 24 include/sound > 12 include/video > > Remember we do not visit all directories - only those listed in include/Kbuild. > > To try it yourself apply following patch and on a configured kernel use: > > make -k headercheck > > Looking at the errors I would assume that at least 75% of the errors > can be fixed in one day but the rest may be a bit more troublesome. > > The open question is if this is worthwhile? Definitely a good idea IMHO. The current practice of 'include enough .h files in the .c file to make it build' has resulted in perversely long #include line sections in .c files. For example arch/x86/kernel/setup.c has 76 headers (!) at the moment, and you have to go down 4 pages in the file before you see the first line of substantial code. Or arch/x86/mm/fault.c had 32 headers - i recently cut that down to 11 only. Nice would be to have a tool that lists the minimum set of required headers for any given .c file, for a current .config. If we run that in allyesconfig we get a pretty good approximation of the headers needed. Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
