On Wednesday 13 January 2010 10:54, Oliver Hartkopp wrote: > Matthias Fuchs wrote: > > >>>>> Any ideas where to dig? > >>>> Please check in can_send() and can_rcv() if there are the same pointer > >>>> values > >>>> in skb->sk . > >>> Good advice. I added some printks. On a 2.6.28 kernel skb->sk is > >>> identical in > >>> can_send and can_rcv. Loopback is working fine. > >>> > >>> On 2.6.18 skb->sk is NULL in can_rcv. > > > > I did some further testing. Doing the same tests on a Debian Etch system > > were successful (Debian kernel 2.6.18-6-486). The problem seems to be with > > the Centos/RHEL kernel 2.6.18-164.6.1.el5. This kernel contains a huge > > amount > > of Redhat patches. I will see if any of them touch net/core/dev.c. Grr :-( > > Maybe a diff with a vanilla 2.6.18 will help - and check especially for > skb_orphan() calls ;-)
I dig a little bit deeper into the Centos/RHEL world. The RL kernel comes with about 430 patches for the net code!!! And even more for the rest of the kernel. Couldn't believe that number. I took the net/core/dev.c and diffed it against a vanilla 2.6.18: see http://www.pastebin.org/75442 There is a new skb_orphan in chunk "-1828,10 +1951,13 @@". This is the redhat patch that caused it: From: Herbert Xu <[email protected]> Date: Wed, 6 May 2009 11:37:16 +0800 Subject: [net] tun: add packet accounting Message-id: [email protected] O-Subject: Re: [RHEL5.4 PATCH] tun: Add packet accounting Bugzilla: 495863 RH-Acked-by: Neil Horman <[email protected]> RH-Acked-by: Michael S. Tsirkin <[email protected]> Hi: RHEL5.4 BZ #495863 We need to add packet accounting to the tun driver so that users such as virtio-net gets congestion feedback which is necessary to prevent packet loss for protocols lacking congestion conctrol (such as UDP) when used in a guest. This is a backport of the following upstream patches: commit 33dccbb050bbe35b88ca8cf1228dcf3e4d4b3554 Author: Herbert Xu <[email protected]> Date: Thu Feb 5 21:25:32 2009 -0800 commit 4cc7f68d65558f683c702d4fe3a5aac4c5227b97 Author: Herbert Xu <[email protected]> Date: Wed Feb 4 16:55:54 2009 -0800 commit 9a279bcbe347496799711155ed41a89bc40f79c5 Author: Herbert Xu <[email protected]> Date: Wed Feb 4 16:55:27 2009 -0800 I took a glace an the very last mentioned backported patch 9a279bcb. Hmm this is one of our old frieds :-) See: http://lists.berlios.de/pipermail/socketcan-users/2009-June/000959.html So to come to a conclusion: Good Socket-CAN, bad RH. You really find 2.6.30 backports in RHEL 2.6.18 kernels. So I think we have to revert he above patch in the RHEL kernel. Matthias _______________________________________________ Socketcan-core mailing list [email protected] https://lists.berlios.de/mailman/listinfo/socketcan-core
