On 11/30/20 9:04 AM, Warner Losh wrote: > On Mon, Nov 30, 2020 at 9:56 AM Michal Meloun <meloun.mic...@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.
Alternatively, given you already are using #ifdef's in all the function bodies, you could instead do something like this: #if _BYTE_ORDER != _LITTLE_ENDIAN /* Existing functions without #if */ #else #define nvme_completion_swapbytes(s) /* Empty macros for the rest */ #endif This gives only a single #if instead of duplicating them in each function, and it avoids the need for __unused. -- John Baldwin _______________________________________________ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
