Re: powerpc/eeh: eeh_pci_enable(): fix checking of post-request state

[Michael Ellerman <mpe@ellerman.id.au>]

On Fri, 2015-23-10 at 06:19:46 UTC, Andrew Donnellan wrote:
> In eeh_pci_enable(), after making the request to set the new options, we
> call eeh_ops->wait_state() to check that the request finished successfully.
> 
> At the moment, if eeh_ops->wait_state() returns 0, we return 0 without
> checking that it reflects the expected outcome. This can lead to callers
> further up the chain incorrectly assuming the slot has been successfully
> unfrozen and continuing to attempt recovery.
> 
> On powernv, this will occur if pnv_eeh_get_pe_state() or
> pnv_eeh_get_phb_state() return 0, which in turn occurs if the relevant OPAL
> call returns OPAL_EEH_STOPPED_MMIO_DMA_FREEZE or
> OPAL_EEH_PHB_ERROR respectively.
> 
> On pseries, this will occur if pseries_eeh_get_state() returns 0, which in
> turn occurs if RTAS reports that the PE is in the MMIO Stopped and DMA
> Stopped states.
> 
> Obviously, none of these cases represent a successful completion of a
> request to thaw MMIO or DMA.
> 
> Fix the check so that a wait_state() return value of 0 won't be considered
> successful for the EEH_OPT_THAW_MMIO or EEH_OPT_THAW_DMA cases.
> 
> Cc: Gavin Shan <gwshan@linux.vnet.ibm.com>
> Signed-off-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
> Acked-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
> Reviewed-by: Daniel Axtens <dja@axtens.net>

Looks like I missed this?

Should it still go in? Is it a fix? If so when did it break, and should it go
to stable?

cheers