Date: Fri, 3 Dec 2010 10:31:32 -0500 From: John Baldwin <jhb@freebsd.org> To: Bruce Cran <bruce@cran.org.uk> Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, Ivan Voras <ivoras@freebsd.org>, Bruce Evans <brde@optusnet.com.au>, Bruce Cran <brucec@freebsd.org>, svn-src-head@freebsd.org Subject: Re: svn commit: r216134 - in head: share/man/man9 sys/amd64/include sys/arm/include sys/i386/include sys/ia64/include sys/mips/include sys/pc98/include sys/powerpc/include sys/sparc64/include sys/sun4v... Message-ID: <201012031031.33073.jhb@freebsd.org> In-Reply-To: <20101203144103.00005a78@unknown> References: <201012022219.oB2MJUx5031472@svn.freebsd.org> <AANLkTinG%2BD=O0w61EVfAOYVagEXLO7TyB%2BNwdECmx%2BEF@mail.gmail.com> <20101203144103.00005a78@unknown>
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On Friday, December 03, 2010 9:41:03 am Bruce Cran wrote: > On Fri, 3 Dec 2010 15:27:13 +0100 > Ivan Voras <ivoras@freebsd.org> wrote: > > > I'd say it depends on if the "specific case that hps raised a few > > years ago" sentence part refers to an actual problem; i.e. did it > > happen in practice? If yes, leaving KASSERTs looks like the best > > option. > > I've found hps's original email thread, which is at > http://lists.freebsd.org/pipermail/freebsd-hackers/2005-June/012342.html . > > The argument for allowing zero-length reads/writes is at > http://lists.freebsd.org/pipermail/freebsd-hackers/2005-June/012348.html . > > I suspect the mistake occurred due to a misunderstanding of the API. > NetBSD have documented it in their man page but not added asserts in > the code: > > "Functions which take a count of bytes have undefined results if the > specified count is zero." I think that is excellent wording and that this case is actually very rare. -- John Baldwin
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