Re: [ 008/153] powerpc/eeh: Fix crash when adding a device in a slot with DDW

[Michael Neuling <mikey@neuling.org>]

Thadeu Lima de Souza Cascardo <cascardo@linux.vnet.ibm.com> wrote:

> On Fri, Mar 08, 2013 at 03:29:55AM +0000, Ben Hutchings wrote:
> > On Fri, 2013-03-08 at 13:51 +1100, Michael Neuling wrote:
> > > This patch is breaking the celleb_defconfig on powerpc with:
> > > 
> > > arch/powerpc/kernel/of_platform.c: In function 'of_pci_phb_probe':
> > > arch/powerpc/kernel/of_platform.c:95:2: error: implicit declaration of
> > > function 'eeh_add_sysfs_files' [-Werror=implicit-function-declaration]
> > 
> > In 3.2 this file doesn't (directly) include <asm/eeh.h> which is where
> > the definition was added.  In mainline it does.
> > 
> > Assuming that this change is actually required for 3.2 (which I'm not
> > sure about), I suppose we just need to add the #include.
> > 
> > Ben.
> > 
> 
> This is not required for 3.2. The patch that *may* have broken DLPAR
> (39baadbf36cee3ede5fdb8a34006d9109e5e2570) was introduced between 3.3
> and 3.4.

Reverting 066f289835f09a3f744d6bac96f25e25d20b3ded (from 3.2.40) fixes
the problem for me so I'm ok if we do that instead.

Mikey

> 
> Regards.
> Cascardo.
> 
> > > Mikey
> > > 
> > > On Mon, Mar 4, 2013 at 2:37 PM, Ben Hutchings <ben@decadent.org.uk> wrote:
> > > > 3.2-stable review patch.  If anyone has any objections, please let me know.
> > > >
> > > > ------------------
> > > >
> > > > From: Thadeu Lima de Souza Cascardo <cascardo@linux.vnet.ibm.com>
> > > >
> > > > commit 6a040ce72598159a74969a2d01ab0ba5ee6536b3 upstream.
> > > >
> > > > 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.
> > > >
> > > > Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@linux.vnet.ibm.com>
> > > > Acked-by: Gavin Shan <shangw@linux.vnet.ibm.com>
> > > > Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> > > > [bwh: Backported to 3.2: adjust context]
> > > > Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
> > > > ---
> > > >  arch/powerpc/include/asm/eeh.h       |    3 +++
> > > >  arch/powerpc/kernel/of_platform.c    |    3 +++
> > > >  arch/powerpc/kernel/pci-common.c     |    7 +++++--
> > > >  arch/powerpc/platforms/pseries/eeh.c |   24 +++++++++++++++++++++++-
> > > >  4 files changed, 34 insertions(+), 3 deletions(-)
> > > >
> > > > --- a/arch/powerpc/include/asm/eeh.h
> > > > +++ b/arch/powerpc/include/asm/eeh.h
> > > > @@ -61,6 +61,7 @@ void __init pci_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_sysfs_files(struct pci_bus *);
> > > >
> > > >  /**
> > > >   * eeh_remove_device_recursive - undo EEH for device & children.
> > > > @@ -105,6 +106,8 @@ static inline void eeh_add_device_tree_e
> > > >
> > > >  static inline void eeh_add_device_tree_late(struct pci_bus *bus) { }
> > > >
> > > > +static inline void eeh_add_sysfs_files(struct pci_bus *bus) { }
> > > > +
> > > >  static inline void eeh_remove_bus_device(struct pci_dev *dev) { }
> > > >  #define EEH_POSSIBLE_ERROR(val, type) (0)
> > > >  #define EEH_IO_ERROR_VALUE(size) (-1UL)
> > > > --- a/arch/powerpc/kernel/of_platform.c
> > > > +++ b/arch/powerpc/kernel/of_platform.c
> > > > @@ -91,6 +91,9 @@ static int __devinit of_pci_phb_probe(st
> > > >         /* Add probed PCI devices to the device model */
> > > >         pci_bus_add_devices(phb->bus);
> > > >
> > > > +       /* sysfs files should only be added after devices are added */
> > > > +       eeh_add_sysfs_files(phb->bus);
> > > > +
> > > >         return 0;
> > > >  }
> > > >
> > > > --- a/arch/powerpc/kernel/pci-common.c
> > > > +++ b/arch/powerpc/kernel/pci-common.c
> > > > @@ -1536,11 +1536,14 @@ void pcibios_finish_adding_to_bus(struct
> > > >         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);
> > > > +       /* sysfs files should only be added after devices are added */
> > > > +       eeh_add_sysfs_files(bus);
> > > >  }
> > > >  EXPORT_SYMBOL_GPL(pcibios_finish_adding_to_bus);
> > > >
> > > > --- a/arch/powerpc/platforms/pseries/eeh.c
> > > > +++ b/arch/powerpc/platforms/pseries/eeh.c
> > > > @@ -1238,7 +1238,6 @@ static void eeh_add_device_late(struct p
> > > >         pdn->pcidev = dev;
> > > >
> > > >         pci_addr_cache_insert_device(dev);
> > > > -       eeh_sysfs_add_device(dev);
> > > >  }
> > > >
> > > >  void eeh_add_device_tree_late(struct pci_bus *bus)
> > > > @@ -1257,6 +1256,29 @@ void eeh_add_device_tree_late(struct pci
> > > >  EXPORT_SYMBOL_GPL(eeh_add_device_tree_late);
> > > >
> > > >  /**
> > > > + * eeh_add_sysfs_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_sysfs_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_sysfs_files(subbus);
> > > > +               }
> > > > +       }
> > > > +}
> > > > +EXPORT_SYMBOL_GPL(eeh_add_sysfs_files);
> > > > +
> > > > +/**
> > > >   * eeh_remove_device - undo EEH setup for the indicated pci device
> > > >   * @dev: pci device to be removed
> > > >   *
> > > >
> > > >
> > > > --
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> > > >
> > > 
> > 
> > -- 
> > Ben Hutchings
> > Always try to do things in chronological order;
> > it's less confusing that way.
> 
>