[Qemu-devel] [PATCH v3 0/6] jobs: fix transactional race condition

[John Snow]

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.

===
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-v3:
https://github.com/jnsnow/qemu/releases/tag/job-fix-race-condition-v3

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               |  4 +--
 block/mirror.c               |  5 +--
 block/replication.c          | 12 ++++---
 block/stream.c               |  4 +--
 blockdev.c                   | 83 ++++++++++++++++++++++++++++----------------
 blockjob.c                   | 55 ++++++++++++++++++++++-------
 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 +++----
 13 files changed, 221 insertions(+), 117 deletions(-)

-- 
2.7.4