scsi: NCR5380: Withhold disconnect privilege for REQUEST SENSE

[ Upstream commit 7c8ed783c2faa1e3f741844ffac41340338ea0f4 ]

This is mostly needed because an AztecMonster II target has been observed
disconnecting REQUEST SENSE commands and then failing to reselect properly.
Suggested-by: NMichael Schmitz <schmitzmic@gmail.com>
Tested-by: NMichael Schmitz <schmitzmic@gmail.com>
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>

drivers/scsi/NCR5380.c

@@ -938,6 +938,8 @@ static bool NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
 	int len;
 	int err;
 	bool ret = true;
+	bool can_disconnect = instance->irq != NO_IRQ &&
+			      cmd->cmnd[0] != REQUEST_SENSE;
 
 	NCR5380_dprint(NDEBUG_ARBITRATION, instance);
 	dsprintk(NDEBUG_ARBITRATION, instance, "starting arbitration, id = %d\n",
@@ -1157,7 +1159,7 @@ static bool NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
 
 	dsprintk(NDEBUG_SELECTION, instance, "target %d selected, going into MESSAGE OUT phase.\n",
 	         scmd_id(cmd));
-	tmp[0] = IDENTIFY(((instance->irq == NO_IRQ) ? 0 : 1), cmd->device->lun);
+	tmp[0] = IDENTIFY(can_disconnect, cmd->device->lun);
 
 	len = 1;
 	data = tmp;