Re: [PATCH v8 16/20] jobs: protect job.aio_context with BQL and job_mutex

[Stefan Hajnoczi]

On Wed, Jun 29, 2022 at 10:15:34AM -0400, Emanuele Giuseppe Esposito wrote:
> In order to make it thread safe, implement a "fake rwlock",
> where we allow reads under BQL *or* job_mutex held, but
> writes only under BQL *and* job_mutex.
> 
> The only write we have is in child_job_set_aio_ctx, which always
> happens under drain (so the job is paused).
> For this reason, introduce job_set_aio_context and make sure that
> the context is set under BQL, job_mutex and drain.
> Also make sure all other places where the aiocontext is read
> are protected.
> 
> Note: at this stage, job_{lock/unlock} and job lock guard macros
> are *nop*.
> 
> Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
> Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
> ---
>  block/replication.c |  6 ++++--
>  blockjob.c          |  3 ++-
>  include/qemu/job.h  | 19 ++++++++++++++++++-
>  job.c               | 12 ++++++++++++
>  4 files changed, 36 insertions(+), 4 deletions(-)

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

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