On Wed, 25 May 2011, Linus Torvalds wrote:
> On Wed, May 25, 2011 at 12:52 PM, Parag Warudkar <parag.lkml@xxxxxxxxx> wrote:
> >
> > +static inline int sdev_early_check(struct scsi_device *sdev)
> > +{
> > + if (!sdev || sdev->sdev_state == SDEV_DEL
> > + || sdev->sdev_state > SDEV_QUIESCE)
> > + return -ENXIO;
> > + return 0;
> > +}
>
> Can somebody explain why it's those states, and nothing else?
>
> Quite frankly, if it's about "don't oops on sdev->queue not existing",
> then test for that. Not for some random and uncommented list of
> states.
List of states and what commands if any are accepeted for each state are
explained in scsi_device.h enum definition of scsi_device_state :
enum scsi_device_state {
SDEV_CREATED = 1, /* device created but not added to sysfs
* Only internal commands allowed (for
inq) */
SDEV_RUNNING, /* device properly configured
* All commands allowed */
SDEV_CANCEL, /* beginning to delete device
* Only error handler commands allowed */
SDEV_DEL, /* device deleted
* no commands allowed */
SDEV_QUIESCE, /* Device quiescent. No block commands
* will be accepted, only specials (which
* originate in the mid-layer) */
SDEV_OFFLINE, /* Device offlined (by error handling or
* user request */
SDEV_BLOCK, /* Device blocked by scsi lld. No
* scsi commands from user or midlayer
* should be issued to the scsi
* lld. */
SDEV_CREATED_BLOCK, /* same as above but for created devices
*/
};
In this case - we check for cases where no commands are allowed and reject
those right away, leaving prep_state_check to do filtering at lower level
for which commands are allowed and which are not as the state permits.
Parag
