James,
Any comments on the patch below?
Thanks
Brian
Brian King wrote:
> Add a max_cmd_len field to the scsi_device struct
> to allow for per device limits of allowable command
> lengths. This patch was submitted earlier and resulted
> in a bit of discussion regarding whether or not
> CDB length is a limitation of the host or the device.
> For ATA, both the host and the device can limit the
> CDB length. Currently libata reads the IDENTIFY
> PACKET DEVICE data for an ATAPI device and sets
> the max_cmd_len in the scsi host for the maximum
> supported CDB length of all ATA/ATAPI devices attached
> to the same scsi host. This patch allows libata to
> set the max CDB length on a per device basis and
> allows the SAS/SATA HBA to set its own max command
> length in the scsi host template.
>
> Signed-off-by: Brian King <brking@xxxxxxxxxx>
> ---
>
> libata-dev-bjking1/drivers/scsi/scsi.c | 3 ++-
> libata-dev-bjking1/drivers/scsi/scsi_scan.c | 1 +
> libata-dev-bjking1/include/scsi/scsi_device.h | 1 +
> 3 files changed, 4 insertions(+), 1 deletion(-)
>
> diff -puN include/scsi/scsi_device.h~scsi_device_cdb_len include/scsi/scsi_device.h
> --- libata-dev/include/scsi/scsi_device.h~scsi_device_cdb_len 2006-04-17 17:17:50.000000000 -0500
> +++ libata-dev-bjking1/include/scsi/scsi_device.h 2006-04-17 17:17:50.000000000 -0500
> @@ -72,6 +72,7 @@ struct scsi_device {
> unsigned int manufacturer; /* Manufacturer of device, for using
> * vendor-specific cmd's */
> unsigned sector_size; /* size in bytes */
> + unsigned char max_cmd_len;
>
> void *hostdata; /* available to low-level driver */
> char type;
> diff -puN drivers/scsi/scsi_scan.c~scsi_device_cdb_len drivers/scsi/scsi_scan.c
> --- libata-dev/drivers/scsi/scsi_scan.c~scsi_device_cdb_len 2006-04-17 17:17:50.000000000 -0500
> +++ libata-dev-bjking1/drivers/scsi/scsi_scan.c 2006-04-17 17:17:50.000000000 -0500
> @@ -218,6 +218,7 @@ static struct scsi_device *scsi_alloc_sd
> sdev->lun = lun;
> sdev->channel = starget->channel;
> sdev->sdev_state = SDEV_CREATED;
> + sdev->max_cmd_len = MAX_COMMAND_SIZE;
> INIT_LIST_HEAD(&sdev->siblings);
> INIT_LIST_HEAD(&sdev->same_target_siblings);
> INIT_LIST_HEAD(&sdev->cmd_list);
> diff -puN drivers/scsi/scsi.c~scsi_device_cdb_len drivers/scsi/scsi.c
> --- libata-dev/drivers/scsi/scsi.c~scsi_device_cdb_len 2006-04-17 17:17:50.000000000 -0500
> +++ libata-dev-bjking1/drivers/scsi/scsi.c 2006-04-17 17:17:50.000000000 -0500
> @@ -610,7 +610,8 @@ int scsi_dispatch_cmd(struct scsi_cmnd *
> * Before we queue this command, check if the command
> * length exceeds what the host adapter can handle.
> */
> - if (CDB_SIZE(cmd) > cmd->device->host->max_cmd_len) {
> + if (CDB_SIZE(cmd) > cmd->device->host->max_cmd_len ||
> + CDB_SIZE(cmd) > cmd->device->max_cmd_len) {
> SCSI_LOG_MLQUEUE(3,
> printk("queuecommand : command too long.\n"));
> cmd->result = (DID_ABORT << 16);
> _
--
Brian King
eServer Storage I/O
IBM Linux Technology Center
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