Re: deadlock when using iothread during backup_clean()

[Paolo Bonzini]

On 9/5/23 12:01, Fiona Ebner wrote:
> Can we assume block_job_remove_all_bdrv() to always hold the job's
> AioContext?

I think so, see job_unref_locked(), job_prepare_locked() and 
job_finalize_single_locked().  These call the callbacks that ultimately 
get to block_job_remove_all_bdrv().
        
> And if yes, can we just tell bdrv_graph_wrlock() that it
> needs to release that before polling to fix the deadlock?

No, but I think it should be released and re-acquired in 
block_job_remove_all_bdrv() itself.

mirror_exit_common() however holds _two_ AioContext locks at the time it 
calls block_job_remove_all_bdrv(), qemu_get_aio_context() has to be 
released and reacquired in mirror_exit_common() itself.

Paolo