A bug RedHat AS 4.0 kernel , is it correct, can anyone confirm
Bug Description :-
The SCSI_IOCTL_GET_IDLUN ioctl fails for LUN number > 255
Bug Details :-
The scsi_idlun structure is defined as follows
typedef struct scsi_idlun {
__u32 dev_id;
__u32 host_unique_id;
} Scsi_Idlun;
The dev_id is a 32 bit value and the HCLT is encoded here.
This is derived from the following code in scsi_ioctl.c
int scsi_ioctl(struct scsi_device *sdev, int cmd, void *arg)
{
.....
case SCSI_IOCTL_GET_IDLUN:
if (verify_area(VERIFY_WRITE, arg, sizeof(struct scsi_idlun)))
return -EFAULT;
__put_user((sdev->id & 0xff)
+ ((sdev->lun & 0xff) << 8)
+ ((sdev->channel & 0xff) << 16)
+ ((sdev->host->host_no & 0xff) << 24),
&((struct scsi_idlun *)arg)->dev_id);
__put_user(sdev->host->unique_id,
&((struct scsi_idlun *)arg)->host_unique_id);
.......
}
This code clearly indicates that all the values (i.e H,C,L and T) are anded with 0xff and hence the limitation for each value (including LUN value) becomes 255.
But the scsi mid layer has the support for 512 LUNs.
So if one has to obtain the LUN number for LUNs > 255 the SCSI_IOCTL_GET_IDLUN ioctl would fail.
Thanks and Regards
Dee[al
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