From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e9.ny.us.ibm.com (e9.ny.us.ibm.com [32.97.182.139]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e9.ny.us.ibm.com", Issuer "GeoTrust SSL CA" (not verified)) by ozlabs.org (Postfix) with ESMTPS id 09EBB2C00C8 for ; Fri, 28 Dec 2012 16:18:53 +1100 (EST) Received: from /spool/local by e9.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 28 Dec 2012 00:18:50 -0500 Received: from d01relay04.pok.ibm.com (d01relay04.pok.ibm.com [9.56.227.236]) by d01dlp03.pok.ibm.com (Postfix) with ESMTP id EB071C90026 for ; Fri, 28 Dec 2012 00:18:47 -0500 (EST) Received: from d03av04.boulder.ibm.com (d03av04.boulder.ibm.com [9.17.195.170]) by d01relay04.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id qBS5IlwE337384 for ; Fri, 28 Dec 2012 00:18:47 -0500 Received: from d03av04.boulder.ibm.com (loopback [127.0.0.1]) by d03av04.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id qBS5IkTa025299 for ; Thu, 27 Dec 2012 22:18:47 -0700 Date: Fri, 28 Dec 2012 13:18:24 +0800 From: Gavin Shan To: Thadeu Lima de Souza Cascardo Subject: Re: [PATCH] ppc/EEH: fix crash when adding a device in a slot with DDW Message-ID: <20121228051824.GA9975@shangw.(null)> References: <1356626040-9384-1-git-send-email-cascardo@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1356626040-9384-1-git-send-email-cascardo@linux.vnet.ibm.com> Cc: shangw@linux.vnet.ibm.com, linux-kernel@vger.kernel.org, stable@vger.kernel.org, paulus@samba.org, bhelgaas@google.com, linuxppc-dev@lists.ozlabs.org Reply-To: Gavin Shan List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Thu, Dec 27, 2012 at 02:34:00PM -0200, Thadeu Lima de Souza Cascardo wrote: >The DDW code uses a eeh_dev struct from the pci_dev. However, this is >not set until eeh_add_device_late is called. > >Since pci_bus_add_devices is called before eeh_add_device_late, the PCI >devices are added to the bus, making drivers' probe hooks to be called. >These will call set_dma_mask, which will call the DDW code, which will >require the eeh_dev struct from pci_dev. This would result in a crash, >due to a NULL dereference. > >Calling eeh_add_device_late after pci_bus_add_devices would make the >system BUG, because device files shouldn't be added to devices there >were not added to the system. So, a new function is needed to add such >files only after pci_bus_add_devices have been called. > Could you please explain for a bit how did you trigger the problem? I'm not sure you got it while doing PCI hotplug or just saw the issue during system bootup stage :-) >Cc: stable@vger.kernel.org >Signed-off-by: Thadeu Lima de Souza Cascardo >--- > arch/powerpc/include/asm/eeh.h | 3 +++ > arch/powerpc/kernel/pci-common.c | 7 +++++-- > arch/powerpc/platforms/pseries/eeh.c | 24 +++++++++++++++++++++++- > 3 files changed, 31 insertions(+), 3 deletions(-) > >diff --git a/arch/powerpc/include/asm/eeh.h b/arch/powerpc/include/asm/eeh.h >index b0ef738..71aac19 100644 >--- a/arch/powerpc/include/asm/eeh.h >+++ b/arch/powerpc/include/asm/eeh.h >@@ -201,6 +201,7 @@ int eeh_dev_check_failure(struct eeh_dev *edev); > void __init eeh_addr_cache_build(void); > void eeh_add_device_tree_early(struct device_node *); > void eeh_add_device_tree_late(struct pci_bus *); >+void eeh_add_device_tree_files(struct pci_bus *); Since the function is going to add EEH specific sysfs files, its name would be something like "eeh_add_sysfs_files" instead of "eeh_add_device_tree_files" :-) > void eeh_remove_bus_device(struct pci_dev *, int); > > /** >@@ -240,6 +241,8 @@ static inline void eeh_add_device_tree_early(struct device_node *dn) { } > > static inline void eeh_add_device_tree_late(struct pci_bus *bus) { } > >+static inline void eeh_add_device_tree_files(struct pci_bus *bus) { } >+ It'd better to rename the function name to "eeh_add_sysfs_files" mentioned as above. > static inline void eeh_remove_bus_device(struct pci_dev *dev, int purge_pe) { } > > static inline void eeh_lock(void) { } >diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c >index 7f94f76..7b1f14c 100644 >--- a/arch/powerpc/kernel/pci-common.c >+++ b/arch/powerpc/kernel/pci-common.c >@@ -1480,11 +1480,14 @@ void pcibios_finish_adding_to_bus(struct pci_bus *bus) > pcibios_allocate_bus_resources(bus); > pcibios_claim_one_bus(bus); > >+ /* Fixup EEH */ >+ eeh_add_device_tree_late(bus); >+ > /* Add new devices to global lists. Register in proc, sysfs. */ > pci_bus_add_devices(bus); > >- /* Fixup EEH */ >- eeh_add_device_tree_late(bus); >+ /* Add EEH sysfs files */ >+ eeh_add_device_tree_files(bus); The function name would be "eeh_add_sysfs_files" as above. > } > EXPORT_SYMBOL_GPL(pcibios_finish_adding_to_bus); > By the way, arch/powerpc/kernel/of_platform.c::of_pci_phb_probe is also calling to eeh_add_device_tree_late() as well. Since you have removed part of the logic from original eeh_add_device_tree_late(), which is add EEH specific sysfs files, and you put that part of logic to eeh_add_device_tree_files(). So I think you also need make the similiar change for of_pci_phb_probe() as well :-) >diff --git a/arch/powerpc/platforms/pseries/eeh.c b/arch/powerpc/platforms/pseries/eeh.c >index 9a04322..a667a34 100644 >--- a/arch/powerpc/platforms/pseries/eeh.c >+++ b/arch/powerpc/platforms/pseries/eeh.c >@@ -788,7 +788,6 @@ static void eeh_add_device_late(struct pci_dev *dev) > dev->dev.archdata.edev = edev; > > eeh_addr_cache_insert_dev(dev); >- eeh_sysfs_add_device(dev); > } > > /** >@@ -815,6 +814,29 @@ void eeh_add_device_tree_late(struct pci_bus *bus) > EXPORT_SYMBOL_GPL(eeh_add_device_tree_late); > > /** >+ * eeh_add_device_tree_files - Add EEH sysfs files for the indicated PCI bus >+ * @bus: PCI bus >+ * >+ * This routine must be used to add EEH sysfs files for PCI >+ * devices which are attached to the indicated PCI bus. The PCI bus >+ * is added after system boot through hotplug or dlpar. >+ */ >+void eeh_add_device_tree_files(struct pci_bus *bus) >+{ >+ struct pci_dev *dev; >+ >+ list_for_each_entry(dev, &bus->devices, bus_list) { >+ eeh_sysfs_add_device(dev); >+ if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) { >+ struct pci_bus *subbus = dev->subordinate; >+ if (subbus) >+ eeh_add_device_tree_files(subbus); >+ } >+ } >+} >+EXPORT_SYMBOL_GPL(eeh_add_device_tree_files); >+ The function name mentioned as above. >+/** > * eeh_remove_device - Undo EEH setup for the indicated pci device > * @dev: pci device to be removed > * @purge_pe: remove the PE or not > Thanks, Gavin