Re: [PATCH 7/7] block/nbd: stop manipulating in_flight counter

[Vladimir Sementsov-Ogievskiy]

15.03.2021 09:06, Roman Kagan wrote:
> As the reconnect logic no longer interferes with drained sections, it
> appears unnecessary to explicitly manipulate the in_flight counter.
>
> Fixes: 5ad81b4946 ("nbd: Restrict connection_co reentrance")

And here you actually allow qemu_aio_coroutine_enter() call in 
nbd_client_attach_aio_context_bh() to enter connection_co in any yield point 
which is possible during drained section. The analysis should be done to be 
sure that all these yield points are safe for reentering by external 
qemu_aio_coroutine_enter(). (By external I mean not by the actual enter() we 
are waiting for at the yield() point. For example qemu_channel_yield() supports 
reentering.. And therefore (as I understand after fast looking through) 
nbd_read() should support reentering too..


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Best regards,
Vladimir