From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Oostdyk Subject: defxx: skb_push() failing? Date: Tue, 26 Mar 2013 10:29:34 -0400 Message-ID: <5151B0CE.5000000@ll.mit.edu> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit Cc: To: Return-path: Received: from MX2.LL.MIT.EDU ([129.55.12.46]:46265 "EHLO mx2.ll.mit.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759793Ab3CZO3p (ORCPT ); Tue, 26 Mar 2013 10:29:45 -0400 Sender: netdev-owner@vger.kernel.org List-ID: Hello, In dfx_xmt_queue_pkt() in defxx.c, there is a skb_push(3) call which makes room for 3 packet request header bytes. There is some discussion in the driver explaining why those three bytes will be available. I have an old FDDI card that I'm trying to bring up: 05:05.0 FDDI network controller: Digital Equipment Corporation PCI-to-PDQ Interface Chip [PFI] (rev 02) Most skbuffs that come through dfx_xmit_queue_pkt() have 11 bytes between skb->head and skb->data. On the other hand, at almost exactly 60-second intervals, an skb arrives that has zero bytes between skb->head and skb->data. This normally causes a kernel panic, and for the time I just skip over such skb's. Does anyone have advice on where I should start digging to find the cause of this? Thanks in advance! - David Oostdyk