Date: Mon, 30 Nov 2020 10:04:02 -0700 From: Warner Losh <imp@bsdimp.com> To: Michal Meloun <mmel@freebsd.org> Cc: Ian Lepore <ian@freebsd.org>, src-committers <src-committers@freebsd.org>, svn-src-all <svn-src-all@freebsd.org>, svn-src-head <svn-src-head@freebsd.org> Subject: Re: svn commit: r368187 - head/sys/dev/nvme Message-ID: <CANCZdfqr6jtHVVPJbsJ0er-RFjRTUfF=iWAGrJ=GBvSkZB3YAA@mail.gmail.com> In-Reply-To: <b32dcdee-52ea-8eed-4dde-1f9f7990a54f@freebsd.org> References: <202011301451.0AUEpn9w002536@repo.freebsd.org> <5bd6eb969c3a198246ab915257375b02c7b14e0c.camel@freebsd.org> <b32dcdee-52ea-8eed-4dde-1f9f7990a54f@freebsd.org>
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On Mon, Nov 30, 2020 at 9:56 AM Michal Meloun <meloun.michal@gmail.com> wrote: > > > On 30.11.2020 17:02, Ian Lepore wrote: > > On Mon, 2020-11-30 at 14:51 +0000, Michal Meloun wrote: > >> Author: mmel > >> Date: Mon Nov 30 14:51:48 2020 > >> New Revision: 368187 > >> URL: https://svnweb.freebsd.org/changeset/base/368187 > >> > >> Log: > >> Unbreak r368167 in userland. Decorate unused arguments. > >> > >> Reported by: kp, tuexen, jenkins, and many others > >> MFC with: r368167 > >> > >> Modified: > >> head/sys/dev/nvme/nvme.h > >> > >> Modified: head/sys/dev/nvme/nvme.h > >> ===================================================================== > >> ========= > >> --- head/sys/dev/nvme/nvme.h Mon Nov 30 14:49:13 2020 (r368186) > >> +++ head/sys/dev/nvme/nvme.h Mon Nov 30 14:51:48 2020 (r368187) > >> @@ -1728,9 +1728,15 @@ extern int nvme_use_nvd; > >> > >> #endif /* _KERNEL */ > >> > >> +#if _BYTE_ORDER != _LITTLE_ENDIAN > >> +#define MODIF > >> +#else > >> +#define MODIF __unused > >> +#endif > >> + > >> /* Endianess conversion functions for NVMe structs */ > >> static inline > >> -void nvme_completion_swapbytes(struct nvme_completion *s) > >> +void nvme_completion_swapbytes(struct nvme_completion *s MODIF) > > > > IMO, this is pretty ugly, it causes the brain to screech to a halt when > > you see it. Why not just add an unconditional __unused to the > > functions? The unused attribute is defined as marking the variable as > > "potentially unused" -- there is no penalty for having it there and > > then actually using the variable. > > > > I understand, (and I have significant tendency to agree) but I did not > find more correct way how to do it. > Are you sure that __unused is defined as *potentially* unused? I cannot > find nothing about this and you known how are compiler guys creative > with generating of new warnings... > I known that C++17 have 'maybe_unused' attribute, but relationship to > standard '__unused' looks unclear. > > In any case, I have not single problem to change this to the proposed > style if we found that this is the optimal way. > __unused means 'don't warn me if this is unused' elsewhere in the tree. Better to use it here. Warner
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