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Re: [PATCH 00/33] migration: capture error reports into Error object
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [PATCH 00/33] migration: capture error reports into Error object |
Date: |
Thu, 4 Feb 2021 18:22:49 +0000 |
User-agent: |
Mutt/1.14.6 (2020-07-11) |
* Daniel P. Berrangé (berrange@redhat.com) wrote:
> Due to its long term heritage most of the migration code just invokes
> 'error_report' when problems hit. This was fine for HMP, since the
> messages get redirected from stderr, into the HMP console. It is not
> OK for QMP because the errors will not be fed back to the QMP client.
>
> This wasn't a terrible real world problem with QMP so far because
> live migration happens in the background, so at least on the target side
> there is not a QMP command that needs to capture the incoming migration.
> It is a problem on the source side but it doesn't hit frequently as the
> source side has fewer failure scenarios. None the less on both sides it
> would be desirable if 'query-migrate' can report errors correctly.
> With the introduction of the load-snapshot QMP commands, the need for
> error reporting becomes more pressing.
>
> Wiring up good error reporting is a large and difficult job, which
> this series does NOT complete. The focus here has been on converting
> all methods in savevm.c which have an 'int' return value capable of
> reporting errors. This covers most of the infrastructure for controlling
> the migration state serialization / protocol.
>
> The remaining part that is missing error reporting are the callbacks in
> the VMStateDescription struct which can return failure codes, but have
> no "Error **errp" parameter. Thinking about how this might be dealt with
> in future, a big bang conversion is likely non-viable. We'll probably
> want to introduce a duplicate set of callbacks with the "Error **errp"
> parameter and convert impls in batches, eventually removing the
> original callbacks. I don't intend todo that myself in the immediate
> future.
>
> IOW, this patch series probably solves 50% of the problem, but we
> still do need the rest to get ideal error reporting.
>
> In doing this savevm conversion I noticed a bunch of places which
> see and then ignore errors. I only fixed one or two of them which
> were clearly dubious. Other places in savevm.c where it seemed it
> was probably ok to ignore errors, I've left using error_report()
> on the basis that those are really warnings. Perhaps they could
> be changed to warn_report() instead.
>
> There are alot of patches here, but I felt it was easier to review
> for correctness if I converted 1 function at a time. The series
> does not neccessarily have to be reviewed/appied in 1 go.
After this series, what do my errors look like, and where do they end
up?
Do I get my nice backtrace shwoing that device failed, then that was
part of that one...
Dave
> Daniel P. Berrangé (33):
> migration: push Error **errp into qemu_loadvm_state()
> migration: push Error **errp into qemu_loadvm_state_header()
> migration: push Error **errp into qemu_loadvm_state_setup()
> migration: push Error **errp into qemu_load_device_state()
> migration: push Error **errp into qemu_loadvm_state_main()
> migration: push Error **errp into qemu_loadvm_section_start_full()
> migration: push Error **errp into qemu_loadvm_section_part_end()
> migration: push Error **errp into loadvm_process_command()
> migration: push Error **errp into loadvm_handle_cmd_packaged()
> migration: push Error **errp into loadvm_postcopy_handle_advise()
> migration: push Error **errp into ram_postcopy_incoming_init()
> migration: push Error **errp into loadvm_postcopy_handle_listen()
> migration: push Error **errp into loadvm_postcopy_handle_run()
> migration: push Error **errp into loadvm_postcopy_ram_handle_discard()
> migration: make loadvm_postcopy_handle_resume() void
> migration: push Error **errp into loadvm_handle_recv_bitmap()
> migration: push Error **errp into loadvm_process_enable_colo()
> migration: push Error **errp into colo_init_ram_cache()
> migration: push Error **errp into check_section_footer()
> migration: push Error **errp into global_state_store()
> migration: remove error reporting from qemu_fopen_bdrv() callers
> migration: push Error **errp into qemu_savevm_state_iterate()
> migration: simplify some error reporting in save_snapshot()
> migration: push Error **errp into qemu_savevm_state_setup()
> migration: push Error **errp into qemu_savevm_state_complete_precopy()
> migration: push Error **errp into
> qemu_savevm_state_complete_precopy_non_iterable()
> migration: push Error **errp into qemu_savevm_state_complete_precopy()
> migration: push Error **errp into qemu_savevm_send_packaged()
> migration: push Error **errp into qemu_savevm_live_state()
> migration: push Error **errp into qemu_save_device_state()
> migration: push Error **errp into qemu_savevm_state_resume_prepare()
> migration: push Error **errp into postcopy_resume_handshake()
> migration: push Error **errp into postcopy_do_resume()
>
> include/migration/colo.h | 2 +-
> include/migration/global_state.h | 2 +-
> migration/colo.c | 12 +-
> migration/global_state.c | 6 +-
> migration/migration.c | 80 ++-
> migration/postcopy-ram.c | 8 +-
> migration/postcopy-ram.h | 2 +-
> migration/ram.c | 17 +-
> migration/ram.h | 4 +-
> migration/savevm.c | 594 ++++++++++--------
> migration/savevm.h | 23 +-
> .../tests/internal-snapshots-qapi.out | 3 +-
> 12 files changed, 427 insertions(+), 326 deletions(-)
>
> --
> 2.29.2
>
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
- [PATCH 22/33] migration: push Error **errp into qemu_savevm_state_iterate(), (continued)
- [PATCH 22/33] migration: push Error **errp into qemu_savevm_state_iterate(), Daniel P . Berrangé, 2021/02/04
- [PATCH 28/33] migration: push Error **errp into qemu_savevm_send_packaged(), Daniel P . Berrangé, 2021/02/04
- [PATCH 31/33] migration: push Error **errp into qemu_savevm_state_resume_prepare(), Daniel P . Berrangé, 2021/02/04
- [PATCH 26/33] migration: push Error **errp into qemu_savevm_state_complete_precopy_non_iterable(), Daniel P . Berrangé, 2021/02/04
- [PATCH 32/33] migration: push Error **errp into postcopy_resume_handshake(), Daniel P . Berrangé, 2021/02/04
- [PATCH 27/33] migration: push Error **errp into qemu_savevm_state_complete_precopy(), Daniel P . Berrangé, 2021/02/04
- [PATCH 24/33] migration: push Error **errp into qemu_savevm_state_setup(), Daniel P . Berrangé, 2021/02/04
- [PATCH 29/33] migration: push Error **errp into qemu_savevm_live_state(), Daniel P . Berrangé, 2021/02/04
- [PATCH 30/33] migration: push Error **errp into qemu_save_device_state(), Daniel P . Berrangé, 2021/02/04
- [PATCH 33/33] migration: push Error **errp into postcopy_do_resume(), Daniel P . Berrangé, 2021/02/04
- Re: [PATCH 00/33] migration: capture error reports into Error object,
Dr. David Alan Gilbert <=
- Re: [PATCH 00/33] migration: capture error reports into Error object, Daniel P . Berrangé, 2021/02/04
- Re: [PATCH 00/33] migration: capture error reports into Error object, Dr. David Alan Gilbert, 2021/02/15
- Re: [PATCH 00/33] migration: capture error reports into Error object, Daniel P . Berrangé, 2021/02/15
- Re: [PATCH 00/33] migration: capture error reports into Error object, Dr. David Alan Gilbert, 2021/02/15
- Re: [PATCH 00/33] migration: capture error reports into Error object, Daniel P . Berrangé, 2021/02/16
- Re: [PATCH 00/33] migration: capture error reports into Error object, Dr. David Alan Gilbert, 2021/02/16