--- Brian King <brking@xxxxxxxxxx> wrote:
> James,
>
> Any comments on the patch below?
Hi Brian, I know I'm not "James" and you didn't direct you email
to me, but I've a question for you:
Why do you want this to live in SCSI Core? I mean, do you find
it objectionable for a proper SATL (no, not libata), to return
proper SK/ASC/ASCQ when a CDB not supported by the device is sent
to the device?
Luben
>
> 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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