Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756498Ab0BEIrP (ORCPT ); Fri, 5 Feb 2010 03:47:15 -0500 Received: from hera.kernel.org ([140.211.167.34]:53836 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753803Ab0BEIrN (ORCPT ); Fri, 5 Feb 2010 03:47:13 -0500 Message-ID: <4B6BDAC0.3090900@kernel.org> Date: Fri, 05 Feb 2010 00:45:52 -0800 From: Yinghai Lu User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.5) Gecko/20091130 SUSE/3.0.0-1.1.1 Thunderbird/3.0 MIME-Version: 1.0 To: Ingo Molnar , "H. Peter Anvin" , Thomas Gleixner CC: Brandon Philips , Suresh Siddha , linux-kernel@vger.kernel.org Subject: [PATCH] x86: keep chip_data in create_irq_nr References: <20100203033109.GA17985@jenkins.home.ifup.org> <4B694DEF.70301@kernel.org> <20100203174216.GB17985@jenkins.home.ifup.org> In-Reply-To: <20100203174216.GB17985@jenkins.home.ifup.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4423 Lines: 133 Brodon found: race happened when two drivers were setting up MSI-X at the same time via pci_enable_msix(). See this dmesg excerpt: [ 85.170610] ixgbe 0000:02:00.1: irq 97 for MSI/MSI-X [ 85.170611] alloc irq_desc for 99 on node -1 [ 85.170613] igb 0000:08:00.1: irq 98 for MSI/MSI-X [ 85.170614] alloc kstat_irqs on node -1 [ 85.170616] alloc irq_2_iommu on node -1 [ 85.170617] alloc irq_desc for 100 on node -1 [ 85.170619] alloc kstat_irqs on node -1 [ 85.170621] alloc irq_2_iommu on node -1 [ 85.170625] ixgbe 0000:02:00.1: irq 99 for MSI/MSI-X [ 85.170626] alloc irq_desc for 101 on node -1 [ 85.170628] igb 0000:08:00.1: irq 100 for MSI/MSI-X [ 85.170630] alloc kstat_irqs on node -1 [ 85.170631] alloc irq_2_iommu on node -1 [ 85.170635] alloc irq_desc for 102 on node -1 [ 85.170636] alloc kstat_irqs on node -1 [ 85.170639] alloc irq_2_iommu on node -1 [ 85.170646] BUG: unable to handle kernel NULL pointer dereference at 0000000000000088 As you can see igb and ixgbe are both alternating on create_irq_nr() via pci_enable_msix() in their probe function. ixgbe: While looping through irq_desc_ptrs[] via create_irq_nr() ixgbe choses irq_desc_ptrs[102] and exits the loop, drops vector_lock and calls dynamic_irq_init. Then it sets irq_desc_ptrs[102]->chip_data = NULL via dynamic_irq_init(). igb: Grabs the vector_lock now and starts looping over irq_desc_ptrs[] via create_irq_nr(). It gets to irq_desc_ptrs[102] and does this: cfg_new = irq_desc_ptrs[102]->chip_data; if (cfg_new->vector != 0) continue; This hits the NULL deref. so let remove the save and restore code. just don't clear it in that path Reported-and-analyzed-by: Brandon Philips Signed-off-by: Yinghai Lu Cc: stable@kernel.org --- arch/x86/kernel/apic/io_apic.c | 9 +++------ include/linux/irq.h | 1 + kernel/irq/chip.c | 15 +++++++++++++-- 3 files changed, 17 insertions(+), 8 deletions(-) Index: linux-2.6/arch/x86/kernel/apic/io_apic.c =================================================================== --- linux-2.6.orig/arch/x86/kernel/apic/io_apic.c +++ linux-2.6/arch/x86/kernel/apic/io_apic.c @@ -3280,12 +3280,9 @@ unsigned int create_irq_nr(unsigned int } spin_unlock_irqrestore(&vector_lock, flags); - if (irq > 0) { - dynamic_irq_init(irq); - /* restore it, in case dynamic_irq_init clear it */ - if (desc_new) - desc_new->chip_data = cfg_new; - } + if (irq > 0) + dynamic_irq_init_keep_chip_data(irq); + return irq; } Index: linux-2.6/include/linux/irq.h =================================================================== --- linux-2.6.orig/include/linux/irq.h +++ linux-2.6/include/linux/irq.h @@ -400,6 +400,7 @@ static inline int irq_has_action(unsigne /* Dynamic irq helper functions */ extern void dynamic_irq_init(unsigned int irq); +void dynamic_irq_init_keep_chip_data(unsigned int irq); extern void dynamic_irq_cleanup(unsigned int irq); /* Set/get chip/data for an IRQ: */ Index: linux-2.6/kernel/irq/chip.c =================================================================== --- linux-2.6.orig/kernel/irq/chip.c +++ linux-2.6/kernel/irq/chip.c @@ -22,7 +22,7 @@ * dynamic_irq_init - initialize a dynamically allocated irq * @irq: irq number to initialize */ -void dynamic_irq_init(unsigned int irq) +static void dynamic_irq_init_x(unsigned int irq, bool keep_chip_data) { struct irq_desc *desc; unsigned long flags; @@ -41,7 +41,8 @@ void dynamic_irq_init(unsigned int irq) desc->depth = 1; desc->msi_desc = NULL; desc->handler_data = NULL; - desc->chip_data = NULL; + if (!keep_chip_data) + desc->chip_data = NULL; desc->action = NULL; desc->irq_count = 0; desc->irqs_unhandled = 0; @@ -54,6 +55,16 @@ void dynamic_irq_init(unsigned int irq) raw_spin_unlock_irqrestore(&desc->lock, flags); } +void dynamic_irq_init(unsigned int irq) +{ + dynamic_irq_init_x(irq, false); +} + +void dynamic_irq_init_keep_chip_data(unsigned int irq) +{ + dynamic_irq_init_x(irq, true); +} + /** * dynamic_irq_cleanup - cleanup a dynamically allocated irq * @irq: irq number to initialize -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/