From: Alexander Duyck <alexander.h.duyck@intel.com>
Date: Mon, 18 Nov 2013 17:59:59 +0000 (-0700)
Subject: PCI: Avoid unnecessary CPU switch when calling driver .probe() method
X-Git-Tag: v3.13-rc4~5^2~6
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=12c3156f10c5d8c5f1fb3f0bbdb8c1ddb1d1f65c;p=pandora-kernel.git

PCI: Avoid unnecessary CPU switch when calling driver .probe() method

If we are already on a CPU local to the device, call the driver .probe()
method directly without using work_on_cpu().

This is a workaround for a lockdep warning in the following scenario:

  pci_call_probe
    work_on_cpu(cpu, local_pci_probe, ...)
      driver .probe
        pci_enable_sriov
          ...
            pci_bus_add_device
              ...
                pci_call_probe
                  work_on_cpu(cpu, local_pci_probe, ...)

It would be better to fix PCI so we don't call VF driver .probe() methods
from inside a PF driver .probe() method, but that's a bigger project.

[bhelgaas: open bugzilla, rework comments & changelog]
Link: https://bugzilla.kernel.org/show_bug.cgi?id=65071
Link: http://lkml.kernel.org/r/CAE9FiQXYQEAZ=0sG6+2OdffBqfLS9MpoN1xviRR9aDbxPxcKxQ@mail.gmail.com
Link: http://lkml.kernel.org/r/20130624195942.40795.27292.stgit@ahduyck-cp1.jf.intel.com
Tested-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Yinghai Lu <yinghai@kernel.org>
---

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