Date: Sun, 27 Feb 2011 15:19:03 +0200 From: Kostik Belousov <kostikbel@gmail.com> To: Bruce Evans <brde@optusnet.com.au> Cc: Bruce Cran <bruce@cran.org.uk>, svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r218966 - head/sys/vm Message-ID: <20110227131903.GE78089@deviant.kiev.zoral.com.ua> In-Reply-To: <20110227230553.N10085@besplex.bde.org> References: <201102231028.p1NASbET045275@svn.freebsd.org> <20110224063233.Y1100@besplex.bde.org> <1298499116.9366.3.camel@core.nessbank> <20110224102112.P1871@besplex.bde.org> <1298800011.24317.7.camel@core.nessbank> <20110227230553.N10085@besplex.bde.org>
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--uZAQk/nhVDxpDIck Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sun, Feb 27, 2011 at 11:12:03PM +1100, Bruce Evans wrote: > On Sun, 27 Feb 2011, Bruce Cran wrote: >=20 > >On Thu, 2011-02-24 at 10:36 +1100, Bruce Evans wrote: > >> > >>I would cast operand(s) in the expression as necessary to prevent overf= low > >>of subexpressions. vm_pindex_t would work, but I prefer to use a type > >>related to the subexpressions. Not sure what that is. Maybe just > >>uintmax_t for safety (even that is not safe if the subexpressions have > >>large values). So: > >> > >> (uintmax_t)swap_bcount * SWAP_META_PAGES * n / mumble. > > > >Following Alan's suggestion, I've attached an updated patch which uses a > >cast to u_long and returns long. >=20 > I thought he only meant to return long. The units being returned are > PAGE_SIZE smaller than the units in the expression. But I don't know > exacty how large swp_bcount can be. If everything fits in a single > object, then vm_size_t =3D u_int on 32-bit machines is enough. I think that return type should be left as vm_offset_t. The calculation basically returns some quantity of type vm_offset_t, divided by PAGE_SIZE. This validates the new return type. The calculation could use vm_offset_t, or uintmax_t cast, probably vm_offset_t is preferred for the same reason. --uZAQk/nhVDxpDIck Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (FreeBSD) iEYEARECAAYFAk1qT0cACgkQC3+MBN1Mb4jZ3wCgzOYhyMq3VyMFcNZ8wBa5bQue o+MAn0I0IQTEWaTiTPuJ6hLddDyQYFoM =nIGG -----END PGP SIGNATURE----- --uZAQk/nhVDxpDIck--
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