Re: [RFC PATCH 0/6] job: replace AioContext lock with job_mutex

[Stefan Hajnoczi <stefanha@redhat.com>]

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On Fri, Jul 16, 2021 at 05:23:50PM +0200, Kevin Wolf wrote:
> Am 13.07.2021 um 15:10 hat Stefan Hajnoczi geschrieben:
> > AIO_WAIT_WHILE() requires that AioContext is acquired according to its
> > documentation, but I'm not sure that's true anymore. Thread-safe/atomic
> > primitives are used by AIO_WAIT_WHILE(), so as long as the condition
> > being waited for is thread-safe too it should work without the
> > AioContext lock.
> 
> Polling something in a different AioContext from the main thread still
> temporarily drops the lock, which crashes if it isn't locked. I'm not
> sure if the documentation claims that the lock is needed in more cases,
> I guess you could interpret it either way.

I'm claiming that the lock doesn't need to be dropped in that case
anymore - as long as the condition we're polling is thread-safe. :)

Have I missed something that still need locking?

We could temporarily introduce an AIO_WAIT_WHILE_UNLOCKED() macro so
that callers can be converted individually.

Stefan

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