Re: [PATCH 01/12] virtio-scsi: replace AioContext lock with tmf_bh_lock

[Kevin Wolf <kwolf@xxxxxxxxxx>]

Am 29.11.2023 um 20:55 hat Stefan Hajnoczi geschrieben:
> Protect the Task Management Function BH state with a lock. The TMF BH
> runs in the main loop thread. An IOThread might process a TMF at the
> same time as the TMF BH is running. Therefore tmf_bh_list and tmf_bh
> must be protected by a lock.
> 
> Run TMF request completion in the IOThread using aio_wait_bh_oneshot().
> This avoids more locking to protect the virtqueue and SCSI layer state.
> 
> Signed-off-by: Stefan Hajnoczi <stefanha@xxxxxxxxxx>

The second part reminds me that the implicit protection of the virtqueue
and SCSI data structures by having all accesses in a single thread is
hard to review and I think we wanted to put some assertions there to
check that we're really running in the right thread. I don't think we
have done that so far, so I suppose after this patch would be the place
in the series to add them, before we remove the protection by the
AioContext lock?

Kevin