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Re: [Qemu-block] [PATCH v4 0/6] jobs: fix transactional race condition
From: |
Jeff Cody |
Subject: |
Re: [Qemu-block] [PATCH v4 0/6] jobs: fix transactional race condition |
Date: |
Wed, 9 Nov 2016 11:11:05 -0500 |
User-agent: |
Mutt/1.5.24 (2015-08-30) |
On Tue, Nov 08, 2016 at 01:50:33AM -0500, John Snow wrote:
> There are a few problems with transactional job completion right now.
>
> First, if jobs complete so quickly they complete before remaining jobs
> get a chance to join the transaction, the completion mode can leave well
> known state and the QLIST can get corrupted and the transactional jobs
> can complete in batches or phases instead of all together.
>
> Second, if two or more jobs defer to the main loop at roughly the same
> time, it's possible for one job's cleanup to directly invoke the other
> job's cleanup from within the same thread, leading to a situation that
> will deadlock the entire transaction.
>
> Thanks to Vladimir for pointing out these modes of failure.
>
> ===
> v4:
> ===
>
> Key:
> [----] : patches are identical
> [####] : number of functional differences between upstream/downstream patch
> [down] : patch is downstream-only
> The flags [FC] indicate (F)unctional and (C)ontextual differences,
> respectively
>
> 001/6:[----] [--] 'blockjob: fix dead pointer in txn list'
> 002/6:[----] [--] 'blockjob: add .clean property'
> 003/6:[----] [--] 'blockjob: add .start field'
> 004/6:[0021] [FC] 'blockjob: add block_job_start'
> 005/6:[0010] [FC] 'blockjob: refactor backup_start as backup_job_create'
> 006/6:[----] [--] 'iotests: add transactional failure race test'
>
> 04: Fix command tracers (Kevin)
> Implement the ability to 'start' a 'paused' job (Kevin, Jeff)
> 05: Replace superfluous conditionals with assertions. (Kevin, Jeff)
>
You forgot to add my R-b's :) I can add them when applying, though.
> ===
> v3:
> ===
>
> - Rebase to origin/master, requisite patches now upstream.
>
> ===
> v2:
> ===
>
> - Correct Vladimir's email (Sorry!)
> - Add test as a variant of an existing test [Vladimir]
>
> ________________________________________________________________________________
>
> For convenience, this branch is available at:
> https://github.com/jnsnow/qemu.git branch job-fix-race-condition
> https://github.com/jnsnow/qemu/tree/job-fix-race-condition
>
> This version is tagged job-fix-race-condition-v4:
> https://github.com/jnsnow/qemu/releases/tag/job-fix-race-condition-v4
>
> John Snow (5):
> blockjob: add .clean property
> blockjob: add .start field
> blockjob: add block_job_start
> blockjob: refactor backup_start as backup_job_create
> iotests: add transactional failure race test
>
> Vladimir Sementsov-Ogievskiy (1):
> blockjob: fix dead pointer in txn list
>
> block/backup.c | 63 +++++++++++++++++++---------------
> block/commit.c | 6 ++--
> block/mirror.c | 7 ++--
> block/replication.c | 12 ++++---
> block/stream.c | 6 ++--
> block/trace-events | 6 ++--
> blockdev.c | 81
> ++++++++++++++++++++++++++++----------------
> blockjob.c | 58 ++++++++++++++++++++++++-------
> include/block/block_int.h | 23 +++++++------
> include/block/blockjob.h | 9 +++++
> include/block/blockjob_int.h | 11 ++++++
> tests/qemu-iotests/124 | 53 +++++++++++++++++++----------
> tests/qemu-iotests/124.out | 4 +--
> tests/test-blockjob-txn.c | 12 +++----
> 14 files changed, 228 insertions(+), 123 deletions(-)
>
> --
> 2.7.4
>
- [Qemu-block] [PATCH v4 0/6] jobs: fix transactional race condition, John Snow, 2016/11/08
- [Qemu-block] [PATCH v4 3/6] blockjob: add .start field, John Snow, 2016/11/08
- [Qemu-block] [PATCH v4 2/6] blockjob: add .clean property, John Snow, 2016/11/08
- [Qemu-block] [PATCH v4 1/6] blockjob: fix dead pointer in txn list, John Snow, 2016/11/08
- [Qemu-block] [PATCH v4 4/6] blockjob: add block_job_start, John Snow, 2016/11/08
- [Qemu-block] [PATCH v4 6/6] iotests: add transactional failure race test, John Snow, 2016/11/08
- [Qemu-block] [PATCH v4 5/6] blockjob: refactor backup_start as backup_job_create, John Snow, 2016/11/08
- Re: [Qemu-block] [PATCH v4 0/6] jobs: fix transactional race condition,
Jeff Cody <=
- Re: [Qemu-block] [PATCH v4 0/6] jobs: fix transactional race condition, Jeff Cody, 2016/11/09
- Re: [Qemu-block] [Qemu-devel] [PATCH v4 0/6] jobs: fix transactional race condition, John Snow, 2016/11/14