Date: Mon, 05 Aug 2013 10:13:02 -0700 From: Navdeep Parhar <np@FreeBSD.org> To: Luigi Rizzo <rizzo@iet.unipi.it> Cc: Adrian Chadd <adrian@freebsd.org>, net@freebsd.org, Bryan Venteicher <bryanv@daemoninthecloset.org>, Giuseppe Lettieri <g.lettieri@iet.unipi.it>, current@freebsd.org Subject: Re: [net] protecting interfaces from races between control and data ? Message-ID: <51FFDD1E.1000206@FreeBSD.org> In-Reply-To: <CA%2BhQ2%2BhuoCCweq7fjoYmH3nyhmhb5DzukEdPSMtaJEWa8Ft0JQ@mail.gmail.com> References: <20130805082307.GA35162@onelab2.iet.unipi.it> <2034715395.855.1375714772487.JavaMail.root@daemoninthecloset.org> <CAJ-VmokT6YKPR7CXsoCavEmWv3W8urZu4eBVgKWaj9iMaVJFZg@mail.gmail.com> <CA%2BhQ2%2BhuoCCweq7fjoYmH3nyhmhb5DzukEdPSMtaJEWa8Ft0JQ@mail.gmail.com>
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On 08/05/13 09:15, Luigi Rizzo wrote: > On Mon, Aug 5, 2013 at 5:46 PM, Adrian Chadd <adrian@freebsd.org> wrote: > >> On 5 August 2013 07:59, Bryan Venteicher <bryanv@daemoninthecloset.org> >> wrote: >> >>> What I've done in my drivers is: >>> * Lock the core mutex >>> * Clear IFF_DRV_RUNNING >>> * Lock/unlock each queue's lock >> >> .. and I think that's the only sane way of doing it. >> > > yeah, this was also the solution we had in mind, i was surprised > not find this pattern in the drivers i have looked at. > > Also there are drivers (chelsio ?) which do not seem to have locks on the > receive interrupt handlers ? This is correct. cxgbe(4) does not have any locks on rx, just a "state" for each rx queue that's maintained with atomic ops. Regards, Navdeep > > Does anyone know how linux copes with the same problem ? > > They seem to have an rtnl_lock() which is a global lock for all > configuration > of netdevices (would replace our per-interface 'core lock' above), > but i am totally unclear on how individual tx threads and interrupt handlers > acknowledge that they have read the change in status. > > cheers > luigi > _______________________________________________ > freebsd-net@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-net > To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org" >
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