linux-toradex.git/drivers/misc/cxl, branch v4.1.10 Linux kernel for Apalis and Colibri modules cxl: Don't remove AFUs/vPHBs in cxl_reset 2015-09-29T17:26:26+00:00 Daniel Axtens dja@axtens.net 2015-08-14T07:41:24+00:00 c3a0355bddf35457563a0d64e91f9dfca7c80280 commit 4e1efb403c1c016ae831bd9988a7d2e5e0af41a0 upstream. If the driver doesn't participate in EEH, the AFUs will be removed by cxl_remove, which will be invoked by EEH. If the driver does particpate in EEH, the vPHB needs to stick around so that the it can particpate. In both cases, we shouldn't remove the AFU/vPHB. Reviewed-by: Cyril Bur <cyrilbur@gmail.com> Signed-off-by: Daniel Axtens <dja@axtens.net> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Reported-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 4e1efb403c1c016ae831bd9988a7d2e5e0af41a0 upstream.

If the driver doesn't participate in EEH, the AFUs will be removed
by cxl_remove, which will be invoked by EEH.

If the driver does particpate in EEH, the vPHB needs to stick around
so that the it can particpate.

In both cases, we shouldn't remove the AFU/vPHB.

Reviewed-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
cxl: Fix unbalanced pci_dev_get in cxl_probe 2015-09-29T17:25:58+00:00 Daniel Axtens dja@axtens.net 2015-09-15T05:04:07+00:00 a847e529661790162905169d28e9fe6e819345b7 commit 2925c2fdf1e0eb642482f5b30577e9435aaa8edb upstream. Currently the first thing we do in cxl_probe is to grab a reference on the pci device. Later on, we call device_register on our adapter. In our remove path, we call device_unregister, but we never call pci_dev_put. We therefore leak the device every time we do a reflash. device_register/unregister is sufficient to hold the reference. Therefore, drop the call to pci_dev_get. Here's why this is safe. The proposed cxl_probe(pdev) calls cxl_adapter_init: a) init calls cxl_adapter_alloc, which creates a struct cxl, conventionally called adapter. This struct contains a device entry, adapter->dev. b) init calls cxl_configure_adapter, where we set adapter->dev.parent = &dev->dev (here dev is the pci dev) So at this point, the cxl adapter's device's parent is the PCI device that I want to be refcounted properly. c) init calls cxl_register_adapter *) cxl_register_adapter calls device_register(&adapter->dev) So now we're in device_register, where dev is the adapter device, and we want to know if the PCI device is safe after we return. device_register(&adapter->dev) calls device_initialize() and then device_add(). device_add() does a get_device(). device_add() also explicitly grabs the device's parent, and calls get_device() on it: parent = get_device(dev->parent); So therefore, device_register() takes a lock on the parent PCI dev, which is what pci_dev_get() was guarding. pci_dev_get() can therefore be safely removed. Fixes: f204e0b8cedd ("cxl: Driver code for powernv PCIe based cards for userspace access") Signed-off-by: Daniel Axtens <dja@axtens.net> Acked-by: Ian Munsie <imunsie@au1.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 2925c2fdf1e0eb642482f5b30577e9435aaa8edb upstream.

Currently the first thing we do in cxl_probe is to grab a reference
on the pci device. Later on, we call device_register on our adapter.
In our remove path, we call device_unregister, but we never call
pci_dev_put. We therefore leak the device every time we do a
reflash.

device_register/unregister is sufficient to hold the reference.
Therefore, drop the call to pci_dev_get.

Here's why this is safe.
The proposed cxl_probe(pdev) calls cxl_adapter_init:
    a) init calls cxl_adapter_alloc, which creates a struct cxl,
       conventionally called adapter. This struct contains a
       device entry, adapter->dev.

    b) init calls cxl_configure_adapter, where we set
       adapter->dev.parent = &dev->dev (here dev is the pci dev)

So at this point, the cxl adapter's device's parent is the PCI
device that I want to be refcounted properly.

    c) init calls cxl_register_adapter
       *) cxl_register_adapter calls device_register(&adapter->dev)

So now we're in device_register, where dev is the adapter device, and
we want to know if the PCI device is safe after we return.

device_register(&adapter->dev) calls device_initialize() and then
device_add().

device_add() does a get_device(). device_add() also explicitly grabs
the device's parent, and calls get_device() on it:

         parent = get_device(dev->parent);

So therefore, device_register() takes a lock on the parent PCI dev,
which is what pci_dev_get() was guarding. pci_dev_get() can therefore
be safely removed.

Fixes: f204e0b8cedd ("cxl: Driver code for powernv PCIe based cards for userspace access")
Signed-off-by: Daniel Axtens <dja@axtens.net>
Acked-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
cxl: Remove racy attempt to force EEH invocation in reset 2015-09-29T17:25:57+00:00 Daniel Axtens dja@axtens.net 2015-08-21T07:25:15+00:00 348b074897b6ce7004a9b4024b2c641a1262a961 commit 9d8e27673c45927fee9e7d8992ffb325a6b0b0e4 upstream. cxl_reset currently PERSTs the slot, and then repeatedly tries to read MMIO space in order to kick off EEH. There are 2 problems with this: it's unnecessary, and it's racy. It's unnecessary because the PERST will bring down the PHB link. That will be picked up by the CAPP, which will send out an HMI. Skiboot, noticing an HMI from the CAPP, will send an OPAL notification to the kernel, which will trigger EEH recovery. It's also racy: the EEH recovery triggered by the CAPP will eventually cause the MMIO space to have its mapping invalidated and the pointer NULLed out. This races with our attempt to read the MMIO space. This is causing OOPSes in testing. Simply drop all the attempts to force EEH detection, and trust that Skiboot will send the notification and that we'll act on it. The Skiboot code to send the EEH notification has been in Skiboot for as long as CAPP recovery has been supported, so we don't need to worry about breaking obscure setups with ancient firmware. Cc: Ryan Grimm <grimm@linux.vnet.ibm.com> Fixes: 62fa19d4b4fd ("cxl: Add ability to reset the card") Signed-off-by: Daniel Axtens <dja@axtens.net> Acked-by: Ian Munsie <imunsie@au1.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 9d8e27673c45927fee9e7d8992ffb325a6b0b0e4 upstream.

cxl_reset currently PERSTs the slot, and then repeatedly tries to
read MMIO space in order to kick off EEH.

There are 2 problems with this: it's unnecessary, and it's racy.

It's unnecessary because the PERST will bring down the PHB link.
That will be picked up by the CAPP, which will send out an HMI.
Skiboot, noticing an HMI from the CAPP, will send an OPAL
notification to the kernel, which will trigger EEH recovery.

It's also racy: the EEH recovery triggered by the CAPP will
eventually cause the MMIO space to have its mapping invalidated
and the pointer NULLed out. This races with our attempt to read
the MMIO space. This is causing OOPSes in testing.

Simply drop all the attempts to force EEH detection, and trust
that Skiboot will send the notification and that we'll act on it.
The Skiboot code to send the EEH notification has been in Skiboot
for as long as CAPP recovery has been supported, so we don't need
to worry about breaking obscure setups with ancient firmware.

Cc: Ryan Grimm <grimm@linux.vnet.ibm.com>
Fixes: 62fa19d4b4fd ("cxl: Add ability to reset the card")
Signed-off-by: Daniel Axtens <dja@axtens.net>
Acked-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
cxl: Check if afu is not null in cxl_slbia 2015-08-10T19:21:50+00:00 Daniel Axtens dja@axtens.net 2015-07-09T23:04:25+00:00 4a0c377cda3533ff80c60c4fd46f787aff4715c3 commit 2c069a118fe1d80c47dca84e1561045fc7f3cc9e upstream. The pointer to an AFU in the adapter's list of AFUs can be null if we're in the process of removing AFUs. The afu_list_lock doesn't guard against this. Say we have 2 slices, and we're in the process of removing cxl. - We remove the AFUs in order (see cxl_remove). In cxl_remove_afu for AFU 0, we take the lock, set adapter->afu[0] = NULL, and release the lock. - Then we get an slbia. In cxl_slbia we take the lock, and set afu = adapter->afu[0], which is NULL. - Therefore our attempt to check afu->enabled will blow up. Therefore, check if afu is a null pointer before dereferencing it. Signed-off-by: Daniel Axtens <dja@axtens.net> Acked-by: Michael Neuling <mikey@neuling.org> Acked-by: Ian Munsie <imunsie@au1.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 2c069a118fe1d80c47dca84e1561045fc7f3cc9e upstream.

The pointer to an AFU in the adapter's list of AFUs can be null
if we're in the process of removing AFUs. The afu_list_lock
doesn't guard against this.

Say we have 2 slices, and we're in the process of removing cxl.
 - We remove the AFUs in order (see cxl_remove). In cxl_remove_afu
   for AFU 0, we take the lock, set adapter->afu[0] = NULL, and
   release the lock.
 - Then we get an slbia. In cxl_slbia we take the lock, and set
   afu = adapter->afu[0], which is NULL.
 - Therefore our attempt to check afu->enabled will blow up.

Therefore, check if afu is a null pointer before dereferencing it.

Signed-off-by: Daniel Axtens <dja@axtens.net>
Acked-by: Michael Neuling <mikey@neuling.org>
Acked-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
cxl: Fix off by one error allowing subsequent mmap page to be accessed 2015-08-10T19:21:50+00:00 Ian Munsie imunsie@au1.ibm.com 2015-07-07T05:45:45+00:00 bbf9f2c9cf06ccb1543c23501f77f6d34868d009 commit 10a5894f2dedd8a26b3132497445b314c0d952c4 upstream. It was discovered that if a process mmaped their problem state area they were able to access one page more than expected, potentially allowing them to access the problem state area of an unrelated process. This was due to a simple off by one error in the mmap fault handler introduced in 0712dc7e73e59d79bcead5d5520acf4e9e917e87 ("cxl: Fix issues when unmapping contexts"), which is fixed in this patch. Fixes: 0712dc7e73e5 ("cxl: Fix issues when unmapping contexts") Signed-off-by: Ian Munsie <imunsie@au1.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 10a5894f2dedd8a26b3132497445b314c0d952c4 upstream.

It was discovered that if a process mmaped their problem state area they
were able to access one page more than expected, potentially allowing
them to access the problem state area of an unrelated process.

This was due to a simple off by one error in the mmap fault handler
introduced in 0712dc7e73e59d79bcead5d5520acf4e9e917e87 ("cxl: Fix issues
when unmapping contexts"), which is fixed in this patch.

Fixes: 0712dc7e73e5 ("cxl: Fix issues when unmapping contexts")
Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Merge tag 'powerpc-3.20-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mpe/linux 2015-02-12T02:15:38+00:00 Linus Torvalds torvalds@linux-foundation.org 2015-02-12T02:15:38+00:00 d3f180ea1a44aecba1b0dab2a253428e77f906bf Pull powerpc updates from Michael Ellerman: - Update of all defconfigs - Addition of a bunch of config options to modernise our defconfigs - Some PS3 updates from Geoff - Optimised memcmp for 64 bit from Anton - Fix for kprobes that allows 'perf probe' to work from Naveen - Several cxl updates from Ian & Ryan - Expanded support for the '24x7' PMU from Cody & Sukadev - Freescale updates from Scott: "Highlights include 8xx optimizations, some more work on datapath device tree content, e300 machine check support, t1040 corenet error reporting, and various cleanups and fixes" * tag 'powerpc-3.20-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mpe/linux: (102 commits) cxl: Add missing return statement after handling AFU errror cxl: Fail AFU initialisation if an invalid configuration record is found cxl: Export optional AFU configuration record in sysfs powerpc/mm: Warn on flushing tlb page in kernel context powerpc/powernv: Add OPAL soft-poweroff routine powerpc/perf/hv-24x7: Document sysfs event description entries powerpc/perf/hv-gpci: add the remaining gpci requests powerpc/perf/{hv-gpci, hv-common}: generate requests with counters annotated powerpc/perf/hv-24x7: parse catalog and populate sysfs with events perf: define EVENT_DEFINE_RANGE_FORMAT_LITE helper perf: add PMU_EVENT_ATTR_STRING() helper perf: provide sysfs_show for struct perf_pmu_events_attr powerpc/kernel: Avoid initializing device-tree pointer twice powerpc: Remove old compile time disabled syscall tracing code powerpc/kernel: Make syscall_exit a local label cxl: Fix device_node reference counting powerpc/mm: bail out early when flushing TLB page powerpc: defconfigs: add MTD_SPI_NOR (new dependency for M25P80) perf/powerpc: reset event hw state when adding it to the PMU powerpc/qe: Use strlcpy() ... 
Pull powerpc updates from Michael Ellerman:

 - Update of all defconfigs

 - Addition of a bunch of config options to modernise our defconfigs

 - Some PS3 updates from Geoff

 - Optimised memcmp for 64 bit from Anton

 - Fix for kprobes that allows 'perf probe' to work from Naveen

 - Several cxl updates from Ian & Ryan

 - Expanded support for the '24x7' PMU from Cody & Sukadev

 - Freescale updates from Scott:
    "Highlights include 8xx optimizations, some more work on datapath
     device tree content, e300 machine check support, t1040 corenet
     error reporting, and various cleanups and fixes"

* tag 'powerpc-3.20-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mpe/linux: (102 commits)
  cxl: Add missing return statement after handling AFU errror
  cxl: Fail AFU initialisation if an invalid configuration record is found
  cxl: Export optional AFU configuration record in sysfs
  powerpc/mm: Warn on flushing tlb page in kernel context
  powerpc/powernv: Add OPAL soft-poweroff routine
  powerpc/perf/hv-24x7: Document sysfs event description entries
  powerpc/perf/hv-gpci: add the remaining gpci requests
  powerpc/perf/{hv-gpci, hv-common}: generate requests with counters annotated
  powerpc/perf/hv-24x7: parse catalog and populate sysfs with events
  perf: define EVENT_DEFINE_RANGE_FORMAT_LITE helper
  perf: add PMU_EVENT_ATTR_STRING() helper
  perf: provide sysfs_show for struct perf_pmu_events_attr
  powerpc/kernel: Avoid initializing device-tree pointer twice
  powerpc: Remove old compile time disabled syscall tracing code
  powerpc/kernel: Make syscall_exit a local label
  cxl: Fix device_node reference counting
  powerpc/mm: bail out early when flushing TLB page
  powerpc: defconfigs: add MTD_SPI_NOR (new dependency for M25P80)
  perf/powerpc: reset event hw state when adding it to the PMU
  powerpc/qe: Use strlcpy()
  ...
cxl: Add missing return statement after handling AFU errror 2015-02-06T00:17:27+00:00 Ian Munsie imunsie@au1.ibm.com 2015-02-04T08:10:38+00:00 a6130ed253a931d2169c26ab0958d81b0dce4d6e We were missing a return statement in the PSL interrupt handler in the case of an AFU error, which would trigger an "Unhandled CXL PSL IRQ" warning. We do actually handle these type of errors (by notifying userspace), so add the missing return IRQ_HANDLED so we don't throw unecessary warnings. Signed-off-by: Ian Munsie <imunsie@au1.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> 
We were missing a return statement in the PSL interrupt handler in the
case of an AFU error, which would trigger an "Unhandled CXL PSL IRQ"
warning. We do actually handle these type of errors (by notifying
userspace), so add the missing return IRQ_HANDLED so we don't throw
unecessary warnings.

Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
cxl: Fail AFU initialisation if an invalid configuration record is found 2015-02-06T00:16:58+00:00 Ian Munsie imunsie@au1.ibm.com 2015-02-04T08:09:02+00:00 3d5be0392f52489b7572903d83f1f267f26e6b69 If an AFU claims to have a configuration record but doesn't actually contain a vendor and device ID, fail the AFU initialisation. Right now this is just a way of politely letting AFU developers know that they need to fix their config space, but later on we may expose the AFUs as actual PCI devices in their own right and don't want to inadvertendly expose an AFU with a bad config space. Signed-off-by: Ian Munsie <imunsie@au1.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> 
If an AFU claims to have a configuration record but doesn't actually
contain a vendor and device ID, fail the AFU initialisation. Right now
this is just a way of politely letting AFU developers know that they
need to fix their config space, but later on we may expose the AFUs as
actual PCI devices in their own right and don't want to inadvertendly
expose an AFU with a bad config space.

Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
cxl: Export optional AFU configuration record in sysfs 2015-02-06T00:16:56+00:00 Ian Munsie imunsie@au1.ibm.com 2015-02-04T08:09:01+00:00 b087e6190ddcd9ae4e8ff2c788d2b32f193e946b An AFU may optionally contain one or more PCIe like configuration records, which can be used to identify the AFU. This patch adds support for exposing the raw config space and the vendor, device and class code under sysfs. These will appear in a subdirectory of the AFU device corresponding with the configuration record number, e.g. cat /sys/class/cxl/afu0.0/cr0/vendor 0x1014 cat /sys/class/cxl/afu0.0/cr0/device 0x4350 cat /sys/class/cxl/afu0.0/cr0/class 0x120000 hexdump -C /sys/class/cxl/afu0.0/cr0/config 00000000 14 10 50 43 00 00 00 00 06 00 00 12 00 00 00 00 |..PC............| 00000010 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| * 00000100 These files behave in much the same way as the equivalent files for PCI devices, with one exception being that the config file is currently read-only and restricted to the root user. It is not necessarily required to be this strict, but we currently do not have a compelling use-case to make it writable and/or world-readable, so I erred on the side of being restrictive. Signed-off-by: Ian Munsie <imunsie@au1.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> 
An AFU may optionally contain one or more PCIe like configuration
records, which can be used to identify the AFU.

This patch adds support for exposing the raw config space and the
vendor, device and class code under sysfs. These will appear in a
subdirectory of the AFU device corresponding with the configuration
record number, e.g.

cat /sys/class/cxl/afu0.0/cr0/vendor
0x1014

cat /sys/class/cxl/afu0.0/cr0/device
0x4350

cat /sys/class/cxl/afu0.0/cr0/class
0x120000

hexdump -C /sys/class/cxl/afu0.0/cr0/config
00000000  14 10 50 43 00 00 00 00  06 00 00 12 00 00 00 00  |..PC............|
00000010  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
00000100

These files behave in much the same way as the equivalent files for PCI
devices, with one exception being that the config file is currently
read-only and restricted to the root user. It is not necessarily
required to be this strict, but we currently do not have a compelling
use-case to make it writable and/or world-readable, so I erred on the
side of being restrictive.

Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
cxl: Fix device_node reference counting 2015-02-02T03:51:31+00:00 Ryan Grimm grimm@linux.vnet.ibm.com 2015-01-29T02:16:04+00:00 6f963ec2d6bf2476a16799eece920acb2100ff1c When unbinding and rebinding the driver on a system with a card in PHB0, this error condition is reached after a few attempts: ERROR: Bad of_node_put() on /pciex@3fffe40000000 CPU: 0 PID: 3040 Comm: bash Not tainted 3.18.0-rc3-12545-g3627ffe #152 Call Trace: [c000000721acb5c0] [c00000000086ef94] .dump_stack+0x84/0xb0 (unreliable) [c000000721acb640] [c00000000073a0a8] .of_node_release+0xd8/0xe0 [c000000721acb6d0] [c00000000044bc44] .kobject_release+0x74/0xe0 [c000000721acb760] [c0000000007394fc] .of_node_put+0x1c/0x30 [c000000721acb7d0] [c000000000545cd8] .cxl_probe+0x1a98/0x1d50 [c000000721acb900] [c0000000004845a0] .local_pci_probe+0x40/0xc0 [c000000721acb980] [c000000000484998] .pci_device_probe+0x128/0x170 [c000000721acba30] [c00000000052400c] .driver_probe_device+0xac/0x2a0 [c000000721acbad0] [c000000000522468] .bind_store+0x108/0x160 [c000000721acbb70] [c000000000521448] .drv_attr_store+0x38/0x60 [c000000721acbbe0] [c000000000293840] .sysfs_kf_write+0x60/0xa0 [c000000721acbc50] [c000000000292500] .kernfs_fop_write+0x140/0x1d0 [c000000721acbcf0] [c000000000208648] .vfs_write+0xd8/0x260 [c000000721acbd90] [c000000000208b18] .SyS_write+0x58/0x100 [c000000721acbe30] [c000000000009258] syscall_exit+0x0/0x98 We are missing a call to of_node_get(). pnv_pci_to_phb_node() should call of_node_get() otherwise np's reference count isn't incremented and it might go away. Rename pnv_pci_to_phb_node() to pnv_pci_get_phb_node() so it's clear it calls of_node_get(). Signed-off-by: Ryan Grimm <grimm@linux.vnet.ibm.com> Acked-by: Ian Munsie <imunsie@au1.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> 
When unbinding and rebinding the driver on a system with a card in PHB0, this
error condition is reached after a few attempts:

ERROR: Bad of_node_put() on /pciex@3fffe40000000
CPU: 0 PID: 3040 Comm: bash Not tainted 3.18.0-rc3-12545-g3627ffe #152
Call Trace:
[c000000721acb5c0] [c00000000086ef94] .dump_stack+0x84/0xb0 (unreliable)
[c000000721acb640] [c00000000073a0a8] .of_node_release+0xd8/0xe0
[c000000721acb6d0] [c00000000044bc44] .kobject_release+0x74/0xe0
[c000000721acb760] [c0000000007394fc] .of_node_put+0x1c/0x30
[c000000721acb7d0] [c000000000545cd8] .cxl_probe+0x1a98/0x1d50
[c000000721acb900] [c0000000004845a0] .local_pci_probe+0x40/0xc0
[c000000721acb980] [c000000000484998] .pci_device_probe+0x128/0x170
[c000000721acba30] [c00000000052400c] .driver_probe_device+0xac/0x2a0
[c000000721acbad0] [c000000000522468] .bind_store+0x108/0x160
[c000000721acbb70] [c000000000521448] .drv_attr_store+0x38/0x60
[c000000721acbbe0] [c000000000293840] .sysfs_kf_write+0x60/0xa0
[c000000721acbc50] [c000000000292500] .kernfs_fop_write+0x140/0x1d0
[c000000721acbcf0] [c000000000208648] .vfs_write+0xd8/0x260
[c000000721acbd90] [c000000000208b18] .SyS_write+0x58/0x100
[c000000721acbe30] [c000000000009258] syscall_exit+0x0/0x98

We are missing a call to of_node_get(). pnv_pci_to_phb_node() should
call of_node_get() otherwise np's reference count isn't incremented and
it might go away. Rename pnv_pci_to_phb_node() to pnv_pci_get_phb_node()
so it's clear it calls of_node_get().

Signed-off-by: Ryan Grimm <grimm@linux.vnet.ibm.com>
Acked-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>