Re: [RFC] virtio_scsi: to poll and kick the virtqueue in timeout handler

[Hannes Reinecke <hare@suse.de>]

On 5/23/21 8:38 AM, Dongli Zhang wrote:
> This RFC is to trigger the discussion about to poll and kick the
> virtqueue on purpose in virtio-scsi timeout handler.
> 
> The virtio-scsi relies on the virtio vring shared between VM and host.
> The VM side produces requests to vring and kicks the virtqueue, while the
> host side produces responses to vring and interrupts the VM side.
> 
> By default the virtio-scsi handler depends on the host timeout handler
> by BLK_EH_RESET_TIMER to give host a chance to perform EH.
> 
> However, this is not helpful for the case that the responses are available
> on vring but the notification from host to VM is lost.
> 
How can this happen?
If responses are lost the communication between VM and host is broken, 
and we should rather reset the virtio rings themselves.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                Kernel Storage Architect
hare@suse.de                              +49 911 74053 688
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