PciDevTracker passes context module instead of instance

[Ed Leafe]

Currently, the code in the PciDevTracker.__init__() method of nova/pci/manager.py reads:

```
    def __init__(self, node_id=None):
        """Create a pci device tracker.

        If a node_id is passed in, it will fetch pci devices information
        from database, otherwise, it will create an empty devices list
        and the resource tracker will update the node_id information later.
        """

        super(PciDevTracker, self).__init__()
        self.stale = {}
        self.node_id = node_id
        self.stats = stats.PciDeviceStats()
        if node_id:
            self.pci_devs = list(
                objects.PciDeviceList.get_by_compute_node(context, node_id))
        else:
            self.pci_devs = []
        self._initial_instance_usage()
```

The problem is that in the call to `objects.PciDeviceList.get_by_compute_node(context, node_id)`, there is no local value for the 'context' parameter, so as a result, the context module defined in the imports is what is passed.

Instead, the parameter should be changed to `context.get_admin_context()`.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/145619

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/145619
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=50ee9dd76e8955dd57e5a7318be023c76c462f67
Submitter: Jenkins
Branch: master

commit 50ee9dd76e8955dd57e5a7318be023c76c462f67
Author: EdLeafe <email address hidden>
Date: Mon Jan 12 15:56:21 2015 +0000

    Pass correct context to get_by_compute_node()

    A recent change to the PciDevTracker class allowed for the passing of
    the compute node ID to the __init__() method, where
    PciDevsList.get_by_compute_node() was called with a 'context' parameter,
    which wasn't defined, resulting in the imported context module being
    passed instead.

    This change requires that the context be passed in to the __init__() for
    the PciDevTracker class, and that that be used to create the
    PciDevsList. The existing import of the context module is no longer
    needed in the pci/manager.py file, so the conflict is no longer a
    problem. The only place in the code that currently instantiates a
    PciDevTracker object is in the ResourceTracker, so that has been updated
    to pass in the context. A unit test to check for context has also been
    added.

    Change-Id: Id136eabacb00e4381c03f12d8484fc90a5eb48b1
    Closes-Bug: #1408480

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/juno
Review: https://review.openstack.org/173225

[Alan Pevec (apevec)]

While this is Low by itself, it is required for Juno backport of bug 1415768

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/173225
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=cfce73b36a3afe4e8be889faf3f5ec78bd19c0c7
Submitter: Jenkins
Branch: stable/juno

commit cfce73b36a3afe4e8be889faf3f5ec78bd19c0c7
Author: EdLeafe <email address hidden>
Date: Mon Jan 12 15:56:21 2015 +0000

    Pass correct context to get_by_compute_node()

    A recent change to the PciDevTracker class allowed for the passing of
    the compute node ID to the __init__() method, where
    PciDevsList.get_by_compute_node() was called with a 'context' parameter,
    which wasn't defined, resulting in the imported context module being
    passed instead.

    This change requires that the context be passed in to the __init__() for
    the PciDevTracker class, and that that be used to create the
    PciDevsList. The existing import of the context module is no longer
    needed in the pci/manager.py file, so the conflict is no longer a
    problem. The only place in the code that currently instantiates a
    PciDevTracker object is in the ResourceTracker, so that has been updated
    to pass in the context. A unit test to check for context has also been
    added.

    (cherry picked from commit 50ee9dd76e8955dd57e5a7318be023c76c462f67)

    Conflicts:
     nova/compute/resource_tracker.py
     nova/tests/pci/test_pci_manager.py

    Closes-Bug: #1408480
    Change-Id: Id136eabacb00e4381c03f12d8484fc90a5eb48b1