From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753724Ab1IBRYr (ORCPT ); Fri, 2 Sep 2011 13:24:47 -0400 Received: from mail-iy0-f174.google.com ([209.85.210.174]:43611 "EHLO mail-iy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753584Ab1IBRYq convert rfc822-to-8bit (ORCPT ); Fri, 2 Sep 2011 13:24:46 -0400 MIME-Version: 1.0 In-Reply-To: References: Date: Fri, 2 Sep 2011 19:24:34 +0200 X-Google-Sender-Auth: Yb3DCi0wdTdxc7M3fQ_3eJI0rG0 Message-ID: Subject: Re: m68k: [v5] Convert to genirq (WIP) From: Geert Uytterhoeven To: Finn Thain , Thomas Gleixner Cc: "Linux/m68k" , linux-kernel@vger.kernel.org Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Sep 2, 2011 at 14:14, Finn Thain wrote: > On Sun, 28 Aug 2011, I wrote: > However, I found another problem. pmac_zilog oopses when its TTY is closed > (see below). And macsonic does the same when the NIC is closed. The trace > says that irq_shutdown() died trying to call the chip irq_mask routine, > when desc->irq_data.chip (in a0) was NULL. Any ideas? > Unable to handle kernel NULL pointer dereference at virtual address   (null) > Oops: 00000000 > Modules linked in: > PC: [<00000000>]   (null) No, it calls a function pointer that's NULL. void irq_shutdown(struct irq_desc *desc) { irq_state_set_disabled(desc); desc->depth = 1; if (desc->irq_data.chip->irq_shutdown) desc->irq_data.chip->irq_shutdown(&desc->irq_data); if (desc->irq_data.chip->irq_disable) desc->irq_data.chip->irq_disable(&desc->irq_data); else desc->irq_data.chip->irq_mask(&desc->irq_data); irq_state_set_masked(desc); } Oops, seems I misread the code and assumed the second "if" was an "else if", as I wrote down in my notes that it calls only one of the 3 functions :-( But it does need either .irq_disable() or .irq_mask(). The following irq_chip structs have both .irq_disable() and .irq_mask() NULL: - arch/m68k/apollo/dn_ints.c:apollo_irq_chip - arch/m68k/kernel/ints.c:auto_irq_chip - arch/m68k/kernel/ints.c:user_irq_chip Since this is on Mac and mac_irq_chip is OK, I guess this is a non-PSC Mac, i.e. the IRQ number is IRQ_MAC_SCC == IRQ_AUTO_4? Thomas: As we cannot disable or mask autovector interrupts at the autovector level, IMHO it doesn't make much sense do add a dummy .irq_mask() function. Can we add an extra check in irq_shutdown() to not call .irq_mask() if it's NULL? Gr{oetje,eeting}s,                         Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that.                                 -- Linus Torvalds