From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754777AbbAZTKc (ORCPT ); Mon, 26 Jan 2015 14:10:32 -0500 Received: from foss-mx-na.foss.arm.com ([217.140.108.86]:43502 "EHLO foss-mx-na.foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755466AbbAZTK2 (ORCPT ); Mon, 26 Jan 2015 14:10:28 -0500 From: Marc Zyngier To: Thomas Gleixner , Jiang Liu Cc: linux-kernel@vger.kernel.org Subject: [PATCH] genirq: MSI: Fix freeing of unallocated MSI Date: Mon, 26 Jan 2015 19:10:19 +0000 Message-Id: <1422299419-6051-1-git-send-email-marc.zyngier@arm.com> X-Mailer: git-send-email 2.1.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org While debugging an unrelated issue with the GICv3 ITS driver, the following trace triggered: WARNING: CPU: 1 PID: 1 at kernel/irq/irqdomain.c:1121 irq_domain_free_irqs+0x160/0x17c() NULL pointer, cannot free irq Modules linked in: CPU: 1 PID: 1 Comm: swapper/0 Tainted: G W 3.19.0-rc6+ #3690 Hardware name: FVP Base (DT) Call trace: [] dump_backtrace+0x0/0x13c [] show_stack+0x10/0x1c [] dump_stack+0x74/0x94 [] warn_slowpath_common+0x9c/0xd4 [] warn_slowpath_fmt+0x5c/0x80 [] irq_domain_free_irqs+0x15c/0x17c [] msi_domain_free_irqs+0x58/0x74 [] free_msi_irqs+0xb4/0x1c0 // The msi_prepare callback fails here [] pci_enable_msix+0x25c/0x3d4 [] pci_enable_msix_range+0x34/0x80 [] vp_try_to_find_vqs+0xec/0x528 [] vp_find_vqs+0x6c/0xa8 [] init_vq+0x120/0x248 [] virtblk_probe+0xb0/0x6bc [] virtio_dev_probe+0x17c/0x214 [] driver_probe_device+0x7c/0x23c [] __driver_attach+0x98/0xa0 [] bus_for_each_dev+0x60/0xb4 [] driver_attach+0x1c/0x28 [] bus_add_driver+0x150/0x208 [] driver_register+0x64/0x130 [] register_virtio_driver+0x24/0x68 [] init+0x70/0xac [] do_one_initcall+0x94/0x1d0 [] kernel_init_freeable+0x144/0x1e4 [] kernel_init+0xc/0xd8 ---[ end trace f9ee562a77cc7bae ]--- The ITS msi_prepare callback having failed, we end-up trying to free MSIs that have never been allocated. Oddly enough, the kernel is pretty upset about it. It turns out that this behaviour was expected before the MSI domain was introduced (and dealt with in arch_teardown_msi_irqs). The obvious fix is to detect this early enough and bail out. Signed-off-by: Marc Zyngier --- kernel/irq/msi.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/kernel/irq/msi.c b/kernel/irq/msi.c index 3e18163..474de5c 100644 --- a/kernel/irq/msi.c +++ b/kernel/irq/msi.c @@ -310,8 +310,15 @@ void msi_domain_free_irqs(struct irq_domain *domain, struct device *dev) struct msi_desc *desc; for_each_msi_entry(desc, dev) { - irq_domain_free_irqs(desc->irq, desc->nvec_used); - desc->irq = 0; + /* + * We might have failed to allocate an MSI early + * enough that there is no IRQ associated to this + * entry. If that's the case, don't do anything. + */ + if (desc->irq) { + irq_domain_free_irqs(desc->irq, desc->nvec_used); + desc->irq = 0; + } } } -- 2.1.4