Re: [Qemu-devel] [PATCH 00/16] PCI device assignment: improve error reporting over QMP

[Laszlo Ersek <lersek@redhat.com>]

On 05/07/14 15:52, Luiz Capitulino wrote:
> On Wed, 30 Apr 2014 15:48:13 +0200
> Laszlo Ersek <lersek@redhat.com> wrote:
> 
>> Hi Luiz,
>>
>> On 04/10/14 10:24, Laszlo Ersek wrote:
>>> This is for <https://bugzilla.redhat.com/show_bug.cgi?id=616415>.
>>>
>>> In general, we want to propagate non-fatal (ie. non-exit()ing,
>>> non-abort()ing) errors to the QMP caller, rather than printing them
>>> on-site. The series focuses on errors raised at PCI assignment time (ie.
>>> reachable from assigned_initfn()), other errors are not converted.
>>>
>>> Errors are not propagated through assigned_initfn(); let's wait for
>>> someone else to convert "kvm-pci-assign" from qdev to QOM. The series is
>>> nonetheless an improvement, because the forwarding of initialization
>>> errors now stops just before device_realize(). We set the
>>> stored/persistent monitor error there.
>>>
>>> Informative and warning messages (that report about circumstances that
>>> don't break the assignment operation) cannot terminate in
>>> qerror_report_err(), because that would set the persistent monitor
>>> error, breaking the high level (QMP) operation.
>>>
>>> A call graph rooted in assigned_initfn() was generated with cflow.
>>> Leaves that could never fail were removed from the graph (and this
>>> property similarly propagated upwards as far as possible).
>>>
>>> The patchset loosely follows a bottom-up algorithm on this calltree. Any
>>> leaf that reports an error internally and returns a related failure is
>>> converted to "throw" an Error structure instead. All direct callers of
>>> the converted leaf are addressed at once, in the same patch, to consume
>>> the error (and they become the new leaves gradually).
>>>
>>> When the leaf to be converted is also called outside of
>>> "hw/i386/kvm/pci-assign.c", the conversion keeps a compatibility
>>> function under the original name, so that conversion of callers
>>> unrelated to PCI assignment can be deferred.
>>>
>>> Reviewers should copy the call graph to a text file, and mark, as the
>>> series progresses, fully converted functions. (Ie. functions that now
>>> report their terminating error messages with Error objects only.)
>>>
>>>   assigned_initfn()
>>>       error_report()
>>>       get_real_device()
>>>           monitor_handle_fd_param()
>>>           error_report()
>>>           get_real_vendor_id()
>>>               get_real_id()
>>>                   error_report()
>>>           get_real_device_id()
>>>               get_real_id()
>>>                   error_report()
>>>       assigned_device_pci_cap_init()
>>>           check_irqchip_in_kernel()
>>>               error_report()
>>>           pci_add_capability()
>>>           error_report()
>>>       assigned_dev_register_msix_mmio()
>>>           error_report()
>>>       assigned_dev_register_regions()
>>>           error_report()
>>>       assign_device()
>>>           error_report()
>>>           assign_failed_examine()
>>>               get_real_vendor_id()
>>>                   get_real_id()
>>>                       error_report()
>>>               get_real_device_id()
>>>                   get_real_id()
>>>                       error_report()
>>>               error_printf()
>>>               error_report()
>>>       assign_intx()
>>>           check_irqchip_in_kernel()
>>>               error_report()
>>>           error_report()
>>>           error_printf()
>>>
>>> Laszlo Ersek (16):
>>>   cutils: tighten qemu_parse_fd()
>>>   monitor: add Error-propagating monitor_handle_fd_param2()
>>>   pci-assign: accept Error from monitor_handle_fd_param2()
>>>   pci-assign: make assign_failed_examine() just format the cause
>>>   pci-assign: propagate errors from get_real_id()
>>>   pci-assign: propagate Error from check_irqchip_in_kernel()
>>>   pci: add Error-propagating pci_add_capability2()
>>>   pci-assign: accept Error from pci_add_capability2()
>>>   pci-assign: assignment should fail if we can't read config space
>>>   pci-assign: propagate errors from get_real_device()
>>>   pci-assign: propagate errors from assigned_device_pci_cap_init()
>>>   pci-assign: propagate errors from assigned_dev_register_msix_mmio()
>>>   pci-assign: propagate errors from assigned_dev_register_regions()
>>>   pci-assign: propagate errors from assign_device()
>>>   pci-assign: propagate errors from assign_intx()
>>>   pci-assign: assigned_initfn(): set monitor error in common error
>>>     handler
>>>
>>>  include/hw/pci/pci.h      |   4 +
>>>  include/monitor/monitor.h |   1 +
>>>  hw/i386/kvm/pci-assign.c  | 273 ++++++++++++++++++++++++++++------------------
>>>  hw/pci/pci.c              |  32 +++++-
>>>  monitor.c                 |  29 ++++-
>>>  util/cutils.c             |  13 ++-
>>>  6 files changed, 232 insertions(+), 120 deletions(-)
>>>
>>
>> I forgot to CC you on this.
> 
> Applied to the qmp branch, thanks.

Awesome, thank you.
Laszlo