Date: Sun, 27 Feb 2011 23:12:03 +1100 (EST) From: Bruce Evans <brde@optusnet.com.au> To: Bruce Cran <bruce@cran.org.uk> Cc: svn-src-head@FreeBSD.org, svn-src-all@FreeBSD.org, src-committers@FreeBSD.org, Bruce Evans <brde@optusnet.com.au> Subject: Re: svn commit: r218966 - head/sys/vm Message-ID: <20110227230553.N10085@besplex.bde.org> In-Reply-To: <1298800011.24317.7.camel@core.nessbank> 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>
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On Sun, 27 Feb 2011, Bruce Cran wrote: > On Thu, 2011-02-24 at 10:36 +1100, Bruce Evans wrote: >> >> I would cast operand(s) in the expression as necessary to prevent overflow >> 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. 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 = u_int on 32-bit machines is enough. Bruce
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