I'd like to ask if SCSI_IOCTL_GET_IDLUN should be deprecated? This is in
response to [Bug 88591] SCSI_IOCTL_GET_IDLUN only returns 8 bits for the SCSI
Target value of which has been seen on the mailing list.
It only returns one byte of id, lun, channel, and host number but we have
SG_GET_SCSI_ID which fills a structure with a separate int for each of those 4
values.
There's two choices in terms of deprecation. The first is immediately
deprecating it by moving it in scsi_ioctl() the other deprecated ioctls so it
no longer works ad issues a warning or the second keep it working for the time
being and add the following before it returns 0 from that function:
if (printk_ratelimit())
printk (KERN_WARNING "program %s is using a deprecated SCSI "
"ioctl SCSI_IOCTL_GET_IDLUN, please convert it to use
SG_GET_SCSI_ID \n",
current->comm);
After some suitable period of time move it to the other deprecated ioctls
scsi_ioctl() where it will stop working and print the same deprecation message
as other deprecated ioctls.
Alternative 3 is to look at the values being compacted into the 4 bytes and if
any of id, lun, channel or host overflow their single byte compacted value
return -EOVERFLOW if any do and then provide a hint to the caller that they
should be using SG_GET_SCSI_ID instead. That would instead change the return 0
in scsi_ioctl() for SCSI_IOCTL_GET_IDLUN to be something like:
if ((sdev->id > 0xff) || (sdev->lun > 0xff) || (sdev->channel >
0xff)
|| (sdev->host->host_no > 0xff)) {
printk(KERN_WARNING "program %s - overflow in ioctl
SCSI_IOCTL_GET_IDLUN, "
"please convert it to use SG_GET_SCSI_ID\n",
current->comm);
return -EOVERFLOW;
} else {
return 0;
}
It allows backwards compatibility (it will still overflow in exactly the same
way) and for a lot of systems it will still work for most uses but provides an
indication that something has gone wrong and the data returned shouldn't be
relied upon to be valid when any of the information has overflowed what it's
been stored in.
Alternative 4 is do nothing people should understand the limitations of what
ioctls they use (they have the source) and TLDP documents SG_GET_SCSI_ID so
anyone using SCSI_IOCTL_GET_IDLUN should be aware of the fact that there are
alternative SG ioctls with wider values for id, lun, channel, and host number.
There may be other possibilities that I've overlooked. After some consensus
about what should be done I'm happy to put together a patch for review.
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