[Skiboot] [PATCH] phb3: Handle fence in phb3_pci_msi_check_q to fix hang

[Stewart Smith]

Ian Munsie <imunsie at au1.ibm.com> writes:
> From: Ian Munsie <imunsie at au1.ibm.com>
>
> If the PHB is fenced during phb3_pci_msi_check_q, it can get stuck in an
> infinite loop waiting to lock the FFI. Further, as the phb lock is held
> during this function it will prevent any other CPUs from dealing with
> the fence, leading to the entire system hanging.
>
> If the PHB_FFI_LOCK returns all Fs, return immediately to allow the
> fence to be dealt with.

Thanks! Merged into stable (both 5.1.x and the one for IBM FW810.40)