On 13-02-20 08:47 AM, Hannes Reinecke wrote:
scsilun_to_int() has an error which prevents it from generating
correct LUN numbers for 64bit values.
Also we should remove the misleading comment about portions of
the LUN being ignored; the initiator should treat the LUN as
an opaque value.
Signed-off-by: Hannes Reinecke <hare@xxxxxxx>
---
drivers/scsi/scsi_scan.c | 9 +++------
1 files changed, 3 insertions(+), 6 deletions(-)
diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index 3e58b22..4f315f5 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -1228,14 +1228,11 @@ static void scsi_sequential_lun_scan(struct scsi_target *starget,
* truncation before using this function.
*
* Notes:
- * The struct scsi_lun is assumed to be four levels, with each level
- * effectively containing a SCSI byte-ordered (big endian) short; the
- * addressing bits of each level are ignored (the highest two bits).
* For a description of the LUN format, post SCSI-3 see the SCSI
* Architecture Model, for SCSI-3 see the SCSI Controller Commands.
*
- * Given a struct scsi_lun of: 0a 04 0b 03 00 00 00 00, this function returns
- * the integer: 0x0b030a04
+ * Given a struct scsi_lun of: 0a 04 0b 03 00 00 00 00, this function
+ * returns the integer: 0x0b030a04
**/
int scsilun_to_int(struct scsi_lun *scsilun)
{
@@ -1244,7 +1241,7 @@ int scsilun_to_int(struct scsi_lun *scsilun)
lun = 0;
for (i = 0; i < sizeof(lun); i += 2)
- lun = lun | (((scsilun->scsi_lun[i] << 8) |
+ lun = lun | (((scsilun->scsi_lun[i] << ((i + 1) * 8)) |
scsilun->scsi_lun[i + 1]) << (i * 8));
return lun;
}
Hmm, this proposed patch is broken for 32 bits (and is thus
broken when extended to uint64_t in patch 2/4 of this series).
This is assuming the example shown in the comment is what
we want this function to do. And the example is ill chosen
since by the T10 (SAM-5) definition it is showing a 3 level
hierarchial LUN which requires 48 bits to represent.
Yet Hannes is correct in a way, because when the existing
scsilun_to_int() is extended to 64 bits, it breaks in a
non-obvious way. If sizeof(int) is 4 (which is often the
case in Linux) then for scsi_lun being an array of (unsigned
char), the expression:
scsi_lun[0] << 32
is zero for values of scsi_lun[0], somewhat surprisingly.
The following works:
static uint64_t
t10_2linux_lun(const unsigned char t10_lun[])
{
const unsigned char * cp;
uint64_t res;
res = (t10_lun[6] << 8) + t10_lun[7];
for (cp = t10_lun + 4; cp >= t10_lun; cp -= 2) {
res <<= 16;
res += (*cp << 8) + *(cp + 1);
}
return res;
}
Doug Gilbert
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