Which comments is unnessary?

Navy navych at 126.com
Tue Jul 14 13:07:14 EDT 2015

Here is a code fragment, which comments is unnessary? I think the all the comments should be remove because the comments should show "What to do rather than "How to do?". Am I right?

 * Unit flag definitions for un_flags.
#define UN_ISOPEN	0x0001		/* Device is open		*/
#define UN_CLOSING	0x0002		/* Line is being closed		*/
#define UN_IMM		0x0004		/* Service immediately		*/
#define UN_BUSY		0x0008		/* Some work this channel	*/
#define UN_BREAKI	0x0010		/* Input break received		*/
#define UN_PWAIT	0x0020		/* Printer waiting for terminal	*/
#define UN_TIME		0x0040		/* Waiting on time		*/
#define UN_EMPTY	0x0080		/* Waiting output queue empty	*/
#define UN_LOW		0x0100		/* Waiting output low water mark*/
#define UN_EXCL_OPEN	0x0200		/* Open for exclusive use	*/
#define UN_WOPEN	0x0400		/* Device waiting for open	*/
#define UN_WIOCTL	0x0800		/* Device waiting for open	*/
#define UN_HANGUP	0x8000		/* Carrier lost			*/

struct device;

 * Structure for terminal or printer unit.
struct un_t {
	int	magic;		/* Unit Magic Number.			*/
	struct	channel_t *un_ch;
	ulong	un_time;
	uint	un_type;
	uint	un_open_count;	/* Counter of opens to port		*/
	struct tty_struct *un_tty;/* Pointer to unit tty structure	*/
	uint	un_flags;	/* Unit flags				*/
	wait_queue_head_t un_flags_wait; /* Place to sleep to wait on unit */
	uint	un_dev;		/* Minor device number			*/
	struct device *un_sysfs;

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