Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757369Ab3FLRVs (ORCPT ); Wed, 12 Jun 2013 13:21:48 -0400 Received: from mx1.redhat.com ([209.132.183.28]:5020 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754873Ab3FLRVr (ORCPT ); Wed, 12 Jun 2013 13:21:47 -0400 Date: Wed, 12 Jun 2013 19:21:32 +0200 From: Radim =?utf-8?B?S3LEjW3DocWZ?= To: Linux Kernel Cc: Kenji Kaneshige Subject: pcie aspm link setup, grandparent instead of parent? Message-ID: <20130612172132.GG27284@hpx.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1241 Lines: 35 Hello, as a consequence of hitting a NULL dereference bug[1] while downstream aspm is setting up link_state, I started to wonder why is the code skipping its parent bus in favour of grandparent's link_state.[2] Is this right? (I have no device to test on ...) Thanks. --- 1: https://bugzilla.redhat.com/show_bug.cgi?id=972381 The bug is hit because "pdev->bus->parent" has NULL "->parent" and thus NULL "->self". 2: "pdev = bus->self", so "pdev->bus->parent == bus->parent->parent" diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c index 403a443..d58e282 100644 --- a/drivers/pci/pcie/aspm.c +++ b/drivers/pci/pcie/aspm.c @@ -527,7 +527,7 @@ static struct pcie_link_state *alloc_pcie_link_state(struct pci_dev *pdev) link->pdev = pdev; if (pci_pcie_type(pdev) == PCI_EXP_TYPE_DOWNSTREAM) { struct pcie_link_state *parent; - parent = pdev->bus->parent->self->link_state; + parent = pdev->bus->self->link_state; if (!parent) { kfree(link); return NULL; -- 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/