From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752253AbaBWVkH (ORCPT ); Sun, 23 Feb 2014 16:40:07 -0500 Received: from www.linutronix.de ([62.245.132.108]:52197 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752084AbaBWVkC (ORCPT ); Sun, 23 Feb 2014 16:40:02 -0500 Message-Id: <20140223212736.562906212@linutronix.de> User-Agent: quilt/0.60-1 Date: Sun, 23 Feb 2014 21:40:09 -0000 From: Thomas Gleixner To: LKML Cc: Ingo Molnar , Peter Zijlstra , Gavin Shan , Benjamin Herrenschmidt , ppc Subject: [patch 03/26] powerpc: eeh: Kill another abuse of irq_desc References: <20140223212703.511977310@linutronix.de> Content-Disposition: inline; filename=powerpc-eeh-kill-more-abuse-of-irq-desc.patch X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org commit 91150af3a (powerpc/eeh: Fix unbalanced enable for IRQ) is another brilliant example of trainwreck engineering. The patch "fixes" the issue of an unbalanced call to irq_enable() which causes a prominent warning by checking the disabled state of the interrupt line and call conditionally into the core code. This is wrong in two aspects: 1) The warning is there to tell users, that they need to fix their asymetric enable/disable patterns by finding the root cause and solving it there. It's definitely not meant to work around it by conditionally calling into the core code depending on the random state of the irq line. Asymetric irq_disable/enable calls are a clear sign of wrong usage of the interfaces which have to be cured at the root and not by somehow hacking around it. 2) The abuse of core internal data structure instead of using the proper interfaces for retrieving the information for the 'hack around' irq_desc is core internal and it's clear enough stated. Replace at least the irq_desc abuse with the proper functions and add a big fat comment why this is absurd and completely wrong. Signed-off-by: Thomas Gleixner Cc: Gavin Shan Cc: Benjamin Herrenschmidt Cc: ppc --- arch/powerpc/kernel/eeh_driver.c | 26 +++++++++++++++++++++----- 1 file changed, 21 insertions(+), 5 deletions(-) Index: tip/arch/powerpc/kernel/eeh_driver.c =================================================================== --- tip.orig/arch/powerpc/kernel/eeh_driver.c +++ tip/arch/powerpc/kernel/eeh_driver.c @@ -143,15 +143,31 @@ static void eeh_disable_irq(struct pci_d static void eeh_enable_irq(struct pci_dev *dev) { struct eeh_dev *edev = pci_dev_to_eeh_dev(dev); - struct irq_desc *desc; if ((edev->mode) & EEH_DEV_IRQ_DISABLED) { edev->mode &= ~EEH_DEV_IRQ_DISABLED; - - desc = irq_to_desc(dev->irq); - if (desc && desc->depth > 0) + /* + * FIXME !!!!! + * + * This is just ass backwards. This maze has + * unbalanced irq_enable/disable calls. So instead of + * finding the root cause it works around the warning + * in the irq_enable code by conditionally calling + * into it. + * + * That's just wrong.The warning in the core code is + * there to tell people to fix their assymetries in + * their own code, not by abusing the core information + * to avoid it. + * + * I so wish that the assymetry would be the other way + * round and a few more irq_disable calls render that + * shit unusable forever. + * + * tglx + */ + if (irqd_irq_disabled(irq_get_irq_data(dev->irq)) enable_irq(dev->irq); - } } /** From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from Galois.linutronix.de (Galois.linutronix.de [IPv6:2001:470:1f0b:db:abcd:42:0:1]) (using TLSv1.2 with cipher DHE-RSA-AES128-SHA (128/128 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 08E552C0331 for ; Mon, 24 Feb 2014 08:40:12 +1100 (EST) Message-Id: <20140223212736.562906212@linutronix.de> Date: Sun, 23 Feb 2014 21:40:09 -0000 From: Thomas Gleixner To: LKML Subject: [patch 03/26] powerpc: eeh: Kill another abuse of irq_desc References: <20140223212703.511977310@linutronix.de> Cc: Peter Zijlstra , Ingo Molnar , ppc , Gavin Shan List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , commit 91150af3a (powerpc/eeh: Fix unbalanced enable for IRQ) is another brilliant example of trainwreck engineering. The patch "fixes" the issue of an unbalanced call to irq_enable() which causes a prominent warning by checking the disabled state of the interrupt line and call conditionally into the core code. This is wrong in two aspects: 1) The warning is there to tell users, that they need to fix their asymetric enable/disable patterns by finding the root cause and solving it there. It's definitely not meant to work around it by conditionally calling into the core code depending on the random state of the irq line. Asymetric irq_disable/enable calls are a clear sign of wrong usage of the interfaces which have to be cured at the root and not by somehow hacking around it. 2) The abuse of core internal data structure instead of using the proper interfaces for retrieving the information for the 'hack around' irq_desc is core internal and it's clear enough stated. Replace at least the irq_desc abuse with the proper functions and add a big fat comment why this is absurd and completely wrong. Signed-off-by: Thomas Gleixner Cc: Gavin Shan Cc: Benjamin Herrenschmidt Cc: ppc --- arch/powerpc/kernel/eeh_driver.c | 26 +++++++++++++++++++++----- 1 file changed, 21 insertions(+), 5 deletions(-) Index: tip/arch/powerpc/kernel/eeh_driver.c =================================================================== --- tip.orig/arch/powerpc/kernel/eeh_driver.c +++ tip/arch/powerpc/kernel/eeh_driver.c @@ -143,15 +143,31 @@ static void eeh_disable_irq(struct pci_d static void eeh_enable_irq(struct pci_dev *dev) { struct eeh_dev *edev = pci_dev_to_eeh_dev(dev); - struct irq_desc *desc; if ((edev->mode) & EEH_DEV_IRQ_DISABLED) { edev->mode &= ~EEH_DEV_IRQ_DISABLED; - - desc = irq_to_desc(dev->irq); - if (desc && desc->depth > 0) + /* + * FIXME !!!!! + * + * This is just ass backwards. This maze has + * unbalanced irq_enable/disable calls. So instead of + * finding the root cause it works around the warning + * in the irq_enable code by conditionally calling + * into it. + * + * That's just wrong.The warning in the core code is + * there to tell people to fix their assymetries in + * their own code, not by abusing the core information + * to avoid it. + * + * I so wish that the assymetry would be the other way + * round and a few more irq_disable calls render that + * shit unusable forever. + * + * tglx + */ + if (irqd_irq_disabled(irq_get_irq_data(dev->irq)) enable_irq(dev->irq); - } } /**