Date: Sat, 12 Mar 2005 10:28:20 -0800 From: Sam Leffler <sam@errno.com> To: Andre Oppermann <andre@freebsd.org> Cc: net@freebsd.org Subject: Re: Giant-free polling [PATCH] Message-ID: <423334C4.9060401@errno.com> In-Reply-To: <42331EED.D7714E05@freebsd.org> References: <20050311110234.GA87255@cell.sick.ru> <E1D9kbt-000FAj-00._pppp-mail-ru@f22.mail.ru> <20050311141450.GF9291@darkness.comp.waw.pl> <20050311142805.GB88801@cell.sick.ru> <42320A3E.1020708@elischer.org> <20050311213544.GH9291@darkness.comp.waw.pl> <42322875.4030404@errno.com> <42331EED.D7714E05@freebsd.org>
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Andre Oppermann wrote: > Sam Leffler wrote: > >>Pawel Jakub Dawidek wrote: >> >>>On Fri, Mar 11, 2005 at 01:14:38PM -0800, Julian Elischer wrote: >>>+> >P> There is still an unresolved problem (in your and our patch as well) of >>>+> >P> using ifnet structure fields without synchronization, as we don't have >>>+> >P> access tointerface's internal mutex, which protects those fields. >>>+> > >>>+> > >>>+> >>>+> you need to add an interface method that has access to it.. >>> >>>I was thinking more about moving interface mutex into ifnet structure, >>>but Robert has some objections IIRC. >>> >> >>I don't know what Robert's objections are but I've considered doing it >>for a while to deal with some locking issues in net80211-based drivers. >> The only issue I can see is if this mutex boxes drivers into a locking >>model that interlocks the rx+tx paths. > > > We don't want this. This would paint us into a corner with modern > high speed hardware that can hanle the rx+tx paths simulaneously. > Depending on the hardware DMA model and driver architecture you > want to have a different locking model. I agree with Robert in > objecting to this. > You did not read what I wrote. The ath driver has separate tx+rx paths and it could benefit from the mutex being in the ifnet structure. Sam
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