Date: Thu, 13 Dec 2007 12:47:19 -0500 From: Stephen Clark <Stephen.Clark@seclark.us> To: Maxime Henrion <mux@FreeBSD.org> Cc: glebius@FreeBSD.org, net@FreeBSD.org Subject: Re: Deadlock in the routing code Message-ID: <47617027.3020500@seclark.us> In-Reply-To: <20071213133817.GC71713@elvis.mu.org> References: <20071213133817.GC71713@elvis.mu.org>
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Maxime Henrion wrote: >Replying to myself on this one, sorry about that. > >I said in my previous mail that I didn't know yet what process was >holding the lock of the rtentry that the routed process is dealing >with in rt_setgate(), and I just could verify that it is held by >the swi1: net thread. > >So, in a nutshell: > >- The routed process does its business on the routing socket, that ends up > calling rt_setgate(). While in rt_setgate() it drops the lock on its > rtentry in order to call rtalloc1(). At this point, the routed > process hold the gateway route (rtalloc1() returns it locked), and it > now tries to re-lock the original rtentry. >- At the same time, the swi net thread calls arpresolve() which ends up > calling rt_check(). Then rt_check() locks the rtentry, and tries to > lock the gateway route. > >A classical case of deadlock with mutexes because of different locking >order. Now, it's not obvious to me how to fix it :-). > >Maxime >_______________________________________________ >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" > > > what version of freebsd is this? -- "They that give up essential liberty to obtain temporary safety, deserve neither liberty nor safety." (Ben Franklin) "The course of history shows that as a government grows, liberty decreases." (Thomas Jefferson)
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