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[PATCH 0/5] migrations: Fix potential rare race of migration-test after
From: |
Peter Xu |
Subject: |
[PATCH 0/5] migrations: Fix potential rare race of migration-test after yank |
Date: |
Tue, 20 Jul 2021 21:21:29 -0400 |
Patch 1 fixes a possible race that migration thread can accidentally skip
join() of rp_thread even if the return thread is enabled. Patch 1 is suspected
to also be the root cause of the recent hard-to-reproduce migration-test
failure here reported by PMM:
https://lore.kernel.org/qemu-devel/YPamXAHwan%2FPPXLf@work-vm/
I didn't reproduce it myself; but after co-debugged with Dave it's suspected
that the race of rp_thread could be the cause. It's not exposed before because
yank is soo strict on releasing instances, while we're not that strict before,
and didn't join() on rp_thread wasn't so dangerous after all when migration
succeeded before.
Patch 2 fixes another theoretical race on accessing from_dst_file spotted by
Dave. I don't think there's known issues with it, but may still worth fixing.
Patch 3 should be a cleanup on yank that I think would be nice to have.
Patch 4-5 are further cleanups to remove the ref==1 check in channel_close(),
finally, as I always thought that's a bit hackish. So I used explicit
unregister of the yank function at necessary places to replace that ref==1 one.
I still think having patch 3-5 altogether would be great, however I think patch
1 should still be the most important to be reviewed. Also it would be great to
know whether patch 1 could fix the known yank crash.
Please review, thanks.
Peter Xu (5):
migration: Fix missing join() of rp_thread
migration: Shutdown src in await_return_path_close_on_source()
migration: Introduce migration_ioc_[un]register_yank()
migration: Teach QEMUFile to be QIOChannel-aware
migration: Move the yank unregister of channel_close out
migration/channel.c | 15 ++-----------
migration/migration.c | 18 +++++++++++----
migration/migration.h | 7 ++++++
migration/multifd.c | 8 ++-----
migration/qemu-file-channel.c | 11 ++-------
migration/qemu-file.c | 17 +++++++++++++-
migration/qemu-file.h | 4 +++-
migration/ram.c | 2 +-
migration/savevm.c | 11 +++++++--
migration/yank_functions.c | 42 +++++++++++++++++++++++++++++++++++
migration/yank_functions.h | 3 +++
11 files changed, 101 insertions(+), 37 deletions(-)
--
2.31.1
- [PATCH 0/5] migrations: Fix potential rare race of migration-test after yank,
Peter Xu <=
[PATCH 3/5] migration: Introduce migration_ioc_[un]register_yank(), Peter Xu, 2021/07/20