-stable vs -current handling of SSD_KEY_MISCOMPARE SCSI sense data

[fox at vader.aacc.edu]

While trying to diagnose an unrelated hardware problem, I stumbled on 
the following code in RELENG_4 sys/cam/scsi/scsi_all.c (1.14.2.11):

scsi_interpret_sense(...)
{
	...
	switch (error_code) {
	...
	case SSD_CURRENT_ERROR:
	{
		switch (sense_key) {
		...
		case SSD_KEY_MISCOMPARE:
			/* decrement the number of retries */
			retry = ccb->ccb_h.retry_count > 0;
			if (retry) {
				error = ERESTART;
				ccb->ccb_h.retry_count--;
			} else {
				error = EIO;
			}
		case SSD_KEY_RECOVERED_ERROR:
			error = 0;	/* not an error */
			break;

The lack of a break before "case SSD_KEY_RECOVERED_ERROR:" means that 
all assignments to error in case "SSD_KEY_MISCOMPARE:" are expensive 
comments, so I doubt that a /* FALLTHROUGH */ was intended. Also, this 
code was added as part of 1.18, then MFC'd in 1.14.2.3, so it was most 
likely deliberate.

However, -current seems to ignore this error. sys/cam/scsi/scsi_all.c 1.44 
has:

const struct sense_key_table_entry sense_key_table[] =
{
	...
	{ SSD_KEY_MISCOMPARE, SS_NOP, "MISCOMPARE" },

If I read the code in sys/cam/cam_periph.c correctly, this matches what
-stable does, but should have s/SS_NOP/SS_RDEF/ to match what I suspect
-stable was meant to do.

OTOH, if -stable is really meant to do nothing in that case, perhaps it 
could do so in a more straightforward way, or have a comment added.

OTGH, I may be missing something obvious.

Perusal of cvs-all and freebsd-scsi archives from around the time 
scsi_all.c 1.21 was commited failed to elicit obvious clues.

I eagerly await clue imparting, sarcasm, flamage, or LARTing.

-- 
"I'd ask if you'd found the right sort of isolated wasteland for your
citadel of dread yet, but that would be a silly question; you're in Utah,
after all." --ESR to Darl McBride (Chief Excessive Ossifier of Squandered 
Clues Obstination), in http://www.catb.org/~esr/writings/mcbride.html