[PATCH] powerpc/eeh: fix deadlock when PE frozen state can't be cleared

[Russell Currey]

On Thu, 2016-12-01 at 11:23 +1100, Andrew Donnellan wrote:
> In eeh_reset_device(), we take the pci_rescan_remove_lock immediately after
> after we call eeh_reset_pe() to reset the PCI controller. We then call
> eeh_clear_pe_frozen_state(), which can return an error. In this case, we
> bail out of eeh_reset_device() without calling pci_unlock_rescan_remove().
> 
> Add a call to pci_unlock_rescan_remove() in the eeh_clear_pe_frozen_state()
> error path so that we don't cause a deadlock later on.
> 
> Reported-by: Pradipta Ghosh <pradghos at in.ibm.com>
> Fixes: 78954700631f ("powerpc/eeh: Avoid I/O access during PE reset")
> Cc: stable at vger.kernel.org
> Signed-off-by: Andrew Donnellan <andrew.donnellan at au1.ibm.com>
> ---

Locking in this function is such a mess, we (I) should revisit it at some point.

Acked-by: Russell Currey <ruscur at russell.cc>