Date: Fri, 30 Apr 1999 16:16:29 -0500 From: Chas Pinckard <cpinckard@dynasty.net> To: FreeBsd Current List <freebsd-current@FreeBSD.ORG> Subject: Re: Any action on PR 10570 ? getting closer to 65K :-( Message-ID: <372A1DAD.A72FD38C@dynasty.net> References: <XFMail.990430112019.jdp@polstra.com>
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John Polstra wrote: > Rodney W. Grimes wrote: > >> Pierre Beyssac wrote: > >> > >> > Wouldn't it be sensible to issue a warning (or panic) when > >> > increasing the reference count reaches 0, rather than causing a > >> > later kernel segfault? It would involve some overhead though, and > >> > I'm not sure having 2^32 routes is currently realistic since most > >> > machines don't even have that many bytes of RAM, but it might be > >> > true one day... > >> > >> It would be pretty hard to create 2^32 routes, given that IPv4 only > >> has 32-bit addresses. :-) Also, if you time it I suspect you'll find > >> that it would take a geological lifetime on a fast machine to add that > >> many routes. > > > > But some of us are playing with IPv6 and it is easy to create >2^32 > > routes in that environment. > > You're being totally unrealistic. You can't create >2^32 of > _anything_ on an i386 without running out of memory. > > Even if you could address that much memory, you or your machine would > be dead from old age long before it managed to add that many routes. > Let's say, _totally_ unrealistically, that you added 100 routes per > second continuously. It would still take you 500 days to wrap the > 32-bit counter. > > Regarding IPv6, it would be a surprise if that structure remained > the same at all for IPv6. > > > The checks could be added _today_ with very little testing needed, > > simple return an error if attempting to wrap the route ref count > > from 65536->0. At least then we don't blow chunks latter and end > > up segfaulting. > > > > This is a real bug fix. > > No it's not. It doesn't fix anything, because your 16-bit counter > has wrapped around and now it's not valid any more. It doesn't > matter whether you detect it and warn about it or not. The damage > is already done. > > On the other hand, increasing the size of the variable eliminates > the problem entirely. And once you do that, the overflow test is > unnecessary. > > John So what about those i586/pentium machines? Do they have the 32bit counters so you can implement the higher bit counts? Chas To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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