Re: [PATCH for-8.2 0/4] block: Fix deadlocks with the stream job

[Stefan Hajnoczi]

On Wed, Nov 15, 2023 at 06:20:08PM +0100, Kevin Wolf wrote:
> This series contains three fixes for deadlocks that follow the same
> pattern: A nested event loop in the main thread waits for an iothread to
> make progress, but the AioContext lock of that iothread is still held by
> the main loop, so it can never make progress.
> 
> We're planning to fully remove the AioContext lock in 9.0, which would
> automatically get rid of this kind of bugs, but it's still there in 8.2,
> so let's fix them individually for this release.
> 
> Kevin Wolf (4):
>   block: Fix bdrv_graph_wrlock() call in blk_remove_bs()
>   block: Fix deadlocks in bdrv_graph_wrunlock()
>   stream: Fix AioContext locking during bdrv_graph_wrlock()
>   iotests: Test two stream jobs in a single iothread
> 
>  include/block/graph-lock.h                    | 15 +++-
>  block.c                                       | 26 +++----
>  block/backup.c                                |  2 +-
>  block/blklogwrites.c                          |  4 +-
>  block/blkverify.c                             |  2 +-
>  block/block-backend.c                         | 10 ++-
>  block/commit.c                                | 10 +--
>  block/graph-lock.c                            | 23 +++++-
>  block/mirror.c                                | 14 ++--
>  block/qcow2.c                                 |  2 +-
>  block/quorum.c                                |  4 +-
>  block/replication.c                           | 10 +--
>  block/snapshot.c                              |  2 +-
>  block/stream.c                                | 10 +--
>  block/vmdk.c                                  | 10 +--
>  blockdev.c                                    |  4 +-
>  blockjob.c                                    |  8 +-
>  tests/unit/test-bdrv-drain.c                  | 20 ++---
>  tests/unit/test-bdrv-graph-mod.c              | 10 +--
>  scripts/block-coroutine-wrapper.py            |  2 +-
>  tests/qemu-iotests/tests/iothreads-stream     | 73 +++++++++++++++++++
>  tests/qemu-iotests/tests/iothreads-stream.out | 11 +++
>  22 files changed, 197 insertions(+), 75 deletions(-)
>  create mode 100755 tests/qemu-iotests/tests/iothreads-stream
>  create mode 100644 tests/qemu-iotests/tests/iothreads-stream.out
> 
> -- 
> 2.41.0
> 

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

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