Il 15/03/2012 03:44, Peter Stuge ha scritto:
> Kevin O'Connor wrote:
>> Subject: [PATCH] Use OUT mode for all zero byte "scsi" transfers.
> ..
>> +++ b/src/blockcmd.c
>> @@ -35,6 +35,13 @@ cdb_cmd_data(struct disk_op_s *op, void *cdbcmd, u16
>> blocksize)
>> }
>> }
>>
>> +// Determine if the command is a request to pull data from the device
>> +int
>> +cdb_is_read(u8 *cdbcmd, u16 blocksize)
>> +{
>> + return blocksize && cdbcmd[0] != CDB_CMD_WRITE_10;
>> +}
>
> Suggest that this only evaluates commands, ..
blocksize == 0 identifies a command that has no DMA, so it's a good way
to catch all the problematic commands, in case more are added in the future.
>
>> diff --git a/src/usb-msc.c b/src/usb-msc.c
>> index dadb9ca..c53a1f5 100644
>> --- a/src/usb-msc.c
>> +++ b/src/usb-msc.c
>> @@ -77,13 +77,13 @@ usb_cmd_data(struct disk_op_s *op, void *cdbcmd, u16
>> blocksize)
>> cbw.dCBWSignature = CBW_SIGNATURE;
>> cbw.dCBWTag = 999; // XXX
>> cbw.dCBWDataTransferLength = bytes;
>> - cbw.bmCBWFlags = (cbw.CBWCB[0] == CDB_CMD_WRITE_10) ? USB_DIR_OUT :
>> USB_DIR_IN;
>> + cbw.bmCBWFlags = cdb_is_read(cdbcmd, blocksize) ? USB_DIR_IN :
>> USB_DIR_OUT;
>
> ..and that blocksize is checked here:
>
> cbw.bmCBWFlags = cdb_is_read(&cbw) && blocksize ? USB_DIR_IN : USB_DIR_OUT;
That would duplicate the check in virtio-scsi too.
>> diff --git a/src/virtio-scsi.c b/src/virtio-scsi.c
>> index 3c59438..50339d7 100644
>> --- a/src/virtio-scsi.c
>> +++ b/src/virtio-scsi.c
>> @@ -31,7 +31,7 @@ struct virtio_lun_s {
>>
>> static int
>> virtio_scsi_cmd(u16 ioaddr, struct vring_virtqueue *vq, struct disk_op_s
>> *op,
>> - void *cdbcmd, u16 target, u16 lun, u32 len)
>> + void *cdbcmd, u16 target, u16 lun, u16 blocksize)
>> {
>> struct virtio_scsi_req_cmd req;
>> struct virtio_scsi_resp_cmd resp;
>> @@ -44,7 +44,8 @@ virtio_scsi_cmd(u16 ioaddr, struct vring_virtqueue *vq,
>> struct disk_op_s *op,
>> req.lun[3] = (lun & 0xff);
>> memcpy(req.cdb, cdbcmd, 16);
>>
>> - int datain = (req.cdb[0] != CDB_CMD_WRITE_10);
>> + u32 len = op->count * blocksize;
>> + int datain = cdb_is_read(cdbcmd, blocksize);
>> int data_idx = (datain ? 2 : 1);
>> int out_num = (datain ? 1 : 2);
>> int in_num = (len ? 3 : 2) - out_num;
>> @@ -89,7 +90,7 @@ virtio_scsi_cmd_data(struct disk_op_s *op, void *cdbcmd,
>> u16 blocksize)
>> return virtio_scsi_cmd(GET_GLOBAL(vlun->ioaddr),
>> GET_GLOBAL(vlun->vq), op, cdbcmd,
>> GET_GLOBAL(vlun->target), GET_GLOBAL(vlun->lun),
>> - blocksize * op->count);
>> + blocksize);
>> }
>
> This also seems to be an unrelated change?
virtio_scsi_cmd needs blocksize to pass it to cdb_is_read. So it's related.
FWIW,
Acked-by: Paolo Bonzini <pbonz...@redhat.com>
Paolo
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