Re: [Qemu-devel] [PATCH for-2.1? 2/2] thread-pool: avoid deadlock in nested aio_poll() calls

[Paolo Bonzini]

Il 14/07/2014 10:36, Paolo Bonzini ha scritto:
> to
>
>             /* In case elem->common.cb() makes a nested aio_poll() call,
>              * next may become invalid as well.  Instead of just
>              * restarting the QLIST_FOREACH_SAFE, go through the BH
>              * once more, which also avoids deadlock if element A's
>              * callback waits for element B and both completed at the
>              * same time.
>              */
>             qemu_bh_schedule(pool->completion_bh);
>             elem->common.cb(elem->common.opaque, elem->ret);
>             qemu_aio_release(elem);

This is of course missing here:

                break;

Paolo

> There is no change in logic, it's just that the goto is switched to a BH
> representing a continuation.  I am then not sure why
> pool->completion_token is necessary?