Re: [Qemu-devel] [PATCH] scsi-block: Add qdev error properties

[Paolo Bonzini <pbonzini@redhat.com>]

On 17/08/2017 14:03, Fam Zheng wrote:
> On Thu, 08/17 13:44, Paolo Bonzini wrote:
>> On 17/08/2017 12:28, Fam Zheng wrote:
>>> This makes the werror/rerror options available on the scsi-block device,
>>> to allow user specify error handling policy in the same way as scsi-hd
>>> etc.
>>>
>>> Signed-off-by: Fam Zheng <famz@redhat.com>
>>
>> I'm not sure this is enough, because you would only obey the
>> rerror/werror action if ioctl fails, not if the ioctl succeeds but the
>> command fails (the "r->status && *r->status" conditional in
>> scsi_disk_req_check_error).
> 
> Yes, I missed that.  Why isn't scsi_handle_rw_error called in that if block
> currently?

A recursive answer is because scsi-block doesn't have rerror and werror
(and it's the only one that sets r->status, see scsi_block_dma_command).

More precisely, scsi_handle_rw_error more or less assumes error != 0
(see the switch statement and blk_error_action), so some other changes
are needed to cover that case---at least not overwrite the sense and
ensure something sensible comes out of the QMP event.

Paolo