powerpc/eeh: Release EEH device state synchronously

Hi everyone,

Here are some fixes and cleanups that have come from other work but that I think stand on their own.

Only one patch ("Release EEH device state synchronously", suggested by Oliver O'Halloran) is a significant change: it moves the cleanup of some EEH device data out of the (possibly asynchronous) device release handler and into the (synchronously called) bus notifier. This is useful for future work as it makes it easier to reason about the lifetimes of EEH structures.

Note that I've left a few WARN_ON_ONCEs in the code because I'm paranoid, but I have not been able to hit them during testing.

Cheers,
Sam.

Notes for v4:
Stopped using rtas_error_rc() as it is too specific, intead just translate the one code that is valid for this RTAS call. Therefore, the new patch to export rtas_error_rc() is dropped.

Notes for v3:
I've tweaked the fix for pseries_eeh_configure_bridge() to return the correct error code (even though it's not used) by calling an already present RTAS function, rtas_error_rc(). However, I had to make another change to export that function and while it does seem like the right thing to do, but I'm concerned it's a bit out of scope for such a small fix.

Notes for v2:

I've dropped both cleanup patches (3/4, 4/4) because that type of cleanup (replacing a call to eeh_rmv_from_parent_pe() with one to eeh_remove_device()) is incorrect: if called during recovery, it will cause edev->pe to remain set when it would have been cleared previously. This would lead to stale information in the edev. I think there should be a way to simplify the code around EEH_PE_KEEP but I'll look at that separately.

Patch set changelog follows:

Patch set v4:
Patch 1/2 (was 2/3): powerpc/eeh: fix pseries_eeh_configure_bridge()
- Just handle the error translation locally, as it's specific to the RTAS call, but log the unaltered code in case it's useful for debugging.
Patch 2/2 (was 3/3): powerpc/eeh: Release EEH device state synchronously Dropped (was 1/3) powerpc/rtas: Export rtas_error_rc

Patch set v3:
Patch 1/3 (new in this version): powerpc/rtas: Export rtas_error_rc Patch 2/3 (was 1/2): powerpc/eeh: fix pseries_eeh_configure_bridge() Patch 3/3 (was 2/2): powerpc/eeh: Release EEH device state synchronously

Patch set v2:
Patch 1/2: powerpc/eeh: fix pseries_eeh_configure_bridge()
Patch 2/2: powerpc/eeh: Release EEH device state synchronously
- Added comment explaining why the add case can't be handled similarly to the remove case. Dropped (was 4/4) powerpc/eeh: Clean up edev cleanup for VFs
Dropped (was 3/4) powerpc/eeh: Remove workaround from eeh_add_device_late()

Patch set v1:
Patch 1/4: powerpc/eeh: fix pseries_eeh_configure_bridge() Patch 2/4: powerpc/eeh: Release EEH device state synchronously Patch 3/4: powerpc/eeh: Remove workaround from eeh_add_device_late() Patch 4/4: powerpc/eeh: Clean up edev cleanup for VFs

Sam Bobroff (2):
powerpc/eeh: fix pseries_eeh_configure_bridge() powerpc/eeh: Release EEH device state synchronously

 arch/powerpc/kernel/eeh.c                    | 31 ++++++++++++++++++++
 arch/powerpc/kernel/pci-hotplug.c            |  2 --
 arch/powerpc/platforms/pseries/eeh_pseries.c |  8 ++++-
 3 files changed, 38 insertions(+), 3 deletions(-)

2.22.0.216.g00a2a96fc9