Date: Tue, 23 Sep 2008 07:05:29 -0300 From: Mario Sergio Fujikawa Ferreira <lioux-list@uol.com.br> To: Robert Watson <rwatson@FreeBSD.org> Cc: Norbert Papke <fbsd-ml@scrapper.ca>, stable@FreeBSD.org Subject: Re: Possible UDP deadlock/panic fix Message-ID: <48D8BF69.6060206@uol.com.br> In-Reply-To: <alpine.BSF.1.10.0809220937320.58772@fledge.watson.org> (sfid-20080922_05543_31152F2E) References: <alpine.BSF.1.10.0809220937320.58772@fledge.watson.org> (sfid-20080922_05543_31152F2E)
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Hi,
That seems to be working. I've been up and running for 7 hours now
with your patch.
The machine is a bit slow but I have both WITNESS and INVARIANTS
enabled so as to make sure everything is fine.
Rergads,
Mario
Robert Watson wrote:
>
> Attached is an MFC candidate for a patch I just merged to 8.x, which
> corrects the UDP lock recursion issue both of you were running into. If
> it settles well for a couple of days in HEAD then I'll go ahead and
> request an MFC from re@, but your confirmation as to whether or not this
> corrects the specific symptoms you are seeing would be very helpful. I
> was able to confirm that it eliminated what appeared to be the same
> problem here when I attempted to reproduce it based on the information
> you provided, so I'm hopeful.\
>
> Thanks,
>
> Robert N M Watson
> Computer Laboratory
> University of Cambridge
>
>
> Property changes on: .
> ___________________________________________________________________
> Modified: svn:mergeinfo
> Merged /head/sys:r183265
>
> Index: netinet6/udp6_usrreq.c
> ===================================================================
> --- netinet6/udp6_usrreq.c (revision 183265)
> +++ netinet6/udp6_usrreq.c (working copy)
> @@ -975,13 +975,23 @@
> error = EINVAL;
> goto out;
> }
> +
> + /*
> + * XXXRW: We release UDP-layer locks before calling
> + * udp_send() in order to avoid recursion. However,
> + * this does mean there is a short window where inp's
> + * fields are unstable. Could this lead to a
> + * potential race in which the factors causing us to
> + * select the UDPv4 output routine are invalidated?
> + */
> + INP_WUNLOCK(inp);
> + INP_INFO_WUNLOCK(&udbinfo);
> if (sin6)
> in6_sin6_2_sin_in_sock(addr);
> pru = inetsw[ip_protox[IPPROTO_UDP]].pr_usrreqs;
> - error = ((*pru->pru_send)(so, flags, m, addr, control,
> + /* addr will just be freed in sendit(). */
> + return ((*pru->pru_send)(so, flags, m, addr, control,
> td));
> - /* addr will just be freed in sendit(). */
> - goto out;
> }
> }
> #endif
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