Messages in this thread | | | From | Rikard Falkeborn <> | Date | Fri, 1 Nov 2019 22:28:57 +0100 | Subject | Re: [Patch v4 2/2] linux/bits.h: Add compile time sanity check of GENMASK inputs |
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On Tue, Oct 22, 2019 at 09:53:06PM +0200, Rikard Falkeborn wrote: > On Fri, Oct 11, 2019 at 07:27:37PM -0700, Andrew Morton wrote: > > On Wed, 9 Oct 2019 23:45:02 +0200 Rikard Falkeborn <rikard.falkeborn@gmail.com> wrote: > > > > > GENMASK() and GENMASK_ULL() are supposed to be called with the high bit > > > as the first argument and the low bit as the second argument. Mixing > > > them will return a mask with zero bits set. > > > > > > > I'm seeing some breakage in code which is newly added in linux-next: > > > > As of next-20191021, those breakages are fixed ([0], [1]). next-20191021 > now builds (at least for x86-64) with the GENMASK compile checks added. > > I also stumbled upon [2], which is a fix for an unused macro in a header > in mips/include/asm. next-201008 contained both v3 of this patch and the > mips header with the bad GENMASK in without build regressions, so it > *should* be ok to include v4 (but given the track record of this patch, > I totally understand if you want to wait until [2] lands in mips-next and > linux-next). > > Rikard > > [0]: https://lore.kernel.org/patchwork/patch/1139777/ > [1]: https://lore.kernel.org/patchwork/patch/1139778/ > [2]: https://lore.kernel.org/linux-mips/20191022192547.480095-1-rikard.falkeborn@gmail.com/T/#u
And as of next-20191031, the mentioned mips-header is fixed [0]. Also, a recently introduced arm-bug has also been fixed. I just built x86-64 and arm64 allmodconfigs without issue.
Trying to get this patch merged feels a bit like playing whack a-mole. Perhaps it would have been better to make it a warning at first, and then promote the warning to an error in a later release? Then everyone would have the warning in their tree when they do development and the number if issues in next would be (almost) zero.
Rikard
[0]: https://lore.kernel.org/linux-mips/20191009013721.qda2bo5teppr7nom@pburton-laptop/T/#m6e7cd9c89ef06240fe3cd36a60bd73eff1a1ea5d [1]: https://www.spinics.net/lists/arm-kernel/msg764473.html
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