Messages in this thread | | | Date | Fri, 28 Dec 2012 10:06:16 -0200 | From | Thadeu Lima de Souza Cascardo <> | Subject | Re: [PATCH] ppc/EEH: fix crash when adding a device in a slot with DDW |
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On Fri, Dec 28, 2012 at 01:18:24PM +0800, Gavin Shan wrote: > 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 :-) >
I did a DLPAR remove followed by a DLPAR add, using drmgr -r and drmgr -a. The reason the issue is not trigerred during bootup is that there is no driver registered yet. So no driver probe will call dma_set_mask.
> >Cc: stable@vger.kernel.org > >Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@linux.vnet.ibm.com> > >--- > > 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" :-)
It's indeed a better name.
> > > 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 :-) >
Good point. I will look into other call sites. However, I don't have access to other platforms to test the patch.
> >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 >
Regards, Thadeu Cascardo.
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