Re: [PATCH v5 1/9] scsi/scsi_bus: switch search direction in scsi_device_find

[Paolo Bonzini]

On 13/09/20 18:02, Maxim Levitsky wrote:
> This change will allow us to convert the bus children list to RCU,
> while not changing the logic of this function
> 
> Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
>  hw/scsi/scsi-bus.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/scsi/scsi-bus.c b/hw/scsi/scsi-bus.c
> index df65cc2223..f8adfbc2a5 100644
> --- a/hw/scsi/scsi-bus.c
> +++ b/hw/scsi/scsi-bus.c
> @@ -1572,7 +1572,7 @@ SCSIDevice *scsi_device_find(SCSIBus *bus, int channel, 
> int id, int lun)
>      BusChild *kid;
>      SCSIDevice *target_dev = NULL;
>  
> -    QTAILQ_FOREACH_REVERSE(kid, &bus->qbus.children, sibling) {
> +    QTAILQ_FOREACH(kid, &bus->qbus.children, sibling) {
>          DeviceState *qdev = kid->child;
>          SCSIDevice *dev = SCSI_DEVICE(qdev);
>  
> @@ -1580,7 +1580,15 @@ SCSIDevice *scsi_device_find(SCSIBus *bus, int 
> channel, int id, int lun)
>              if (dev->lun == lun) {
>                  return dev;
>              }
> -            target_dev = dev;
> +
> +            /*
> +             * If we don't find exact match (channel/bus/lun),
> +             * we will return the first device which matches channel/bus
> +             */
> +
> +            if (!target_dev) {
> +                target_dev = dev;
> +            }
>          }
>      }
>      return target_dev;
> 

I think this breaks the detection of duplicate LUNs.  I'll play with it
and let you know.

Paolo