Hi Arnd, 2017-08-21 4:51 GMT+09:00 Arnd Bergmann <arnd@xxxxxxxx>: > On Sun, Aug 20, 2017 at 3:19 PM, Masahiro Yamada > <yamada.masahiro@xxxxxxxxxxxxx> wrote: >> 2017-07-20 16:24 GMT+09:00 Arnd Bergmann <arnd@xxxxxxxx>: >>> - enable all three warnings with "make W=1" in 4.13, but leave them >>> disabled by default. >>> - backport Linus' patch, plus the follow-up for W=1 to stable kernels, >>> to allow stable kernels to build cleanly >>> - backport the patches that address any other gcc-7 warnings, as >>> well as those that are not obvious false-positives to stable kernels >>> - In 4.14+, use my version above and address all int-in-bool-context >>> and format-overflow warnings, but only use -Wformat-truncation >>> with make W=1. >>> >> >> Talking about 4.14+, shall we move -Wformat-truncation >> from the top Makefile (always disable) to >> Makefile.extrawarn (enable with W=1) ? > > I dropped the ball on this one, sorry. I think we should do this for > all three warnings (format-overflow, format-truncation and > int-in-bool-context) for the time being. > > In case of format-truncation, there are countless warnings, > most of them false-postives, so we simply can't enable them > by default. > > For -Wformat-overflow, there is one patch that I need to > rewrite, all my other patches are pending for 4.14, see > https://patchwork.kernel.org/patch/9840801/ for the missing > one. This should be trivial to fix. However, enabling > CONFIG_UBSAN_SANITIZE_ALL results in seven additional > false positives. I created an patch for this in > https://pastebin.com/CD7nhRNp but can't submit that as it's > obviously bogus. I reported the gcc bug as > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81592 > > What we could do there is to disable the warning if > CONFIG_UBSAN_SANITIZE_ALL is turned on (like > we do for -Wmaybe-uninitialized in > CONFIG_UBSAN_SANITIZE_ALL) but leave it on otherwise. > > I submitted patches for all -Wint-in-bool-context in arm/arm64/x86 > randconfig builds, but there are still six known warnings for which > my patches did not get queued for 4.14. > I have to revisit those all to decide whether we can find an > acceptable workaround in the kernel and enable the warning again > by default, or leave it in W=1 until gcc improves enough. > I was just wondering how to handle your original patch. I do not mean to press you. We can take our time to make the right decision. Thanks! -- Best Regards Masahiro Yamada