NAME
mq_init,
mq_enqueue, mq_push,
mq_dequeue, mq_enlist,
mq_delist, mq_dechain,
mq_len, mq_empty,
mq_full, mq_hdatalen,
mq_purge, mq_drops,
mq_set_maxlen,
MBUF_QUEUE_INITIALIZER —
mbuf queue API
SYNOPSIS
#include
<sys/mbuf.h>
void
mq_init(struct
mbuf_queue *mq, unsigned
int maxlen, int
ipl);
int
mq_enqueue(struct
mbuf_queue *mq, struct
mbuf *m);
int
mq_push(struct
mbuf_queue *mq, struct
mbuf *m);
struct mbuf *
mq_dequeue(struct
mbuf_queue *mq);
int
mq_enlist(struct
mbuf_queue *mq, struct
mbuf_list *ml);
void
mq_delist(struct
mbuf_queue *mq, struct
mbuf_list *ml);
struct mbuf *
mq_dechain(struct
mbuf_queue *mq);
unsigned int
mq_len(struct
mbuf_queue *mq);
int
mq_empty(struct
mbuf_queue *mq);
int
mq_full(struct
mbuf_queue *mq);
unsigned int
mq_hdatalen(struct
mbuf_queue *mq);
unsigned int
mq_purge(struct
mbuf_queue *mq);
unsigned int
mq_drops(struct
mbuf_queue *mq);
void
mq_set_maxlen(struct
mbuf_queue *mq, unsigned
int);
struct mbuf_queue
MBUF_QUEUE_INITIALIZER(unsigned
int maxlen, int
ipl);
DESCRIPTION
The mbuf queue API provides implementations of data structures and operations for queueing mbufs and lists of mbufs between contexts.
mbuf_queue data structures provide a superset of the functionality available in mbuf_lists, and protect themselves internally with a mutex(9), making them useful for moving mbufs between contexts or subsystems. Additionally, mbuf_queues provide a limit on the number of mbufs that may be queued.
mbuf_queue structures support the following functionality:
- Insertion of a new mbuf at the end of the queue.
- Removal of an mbuf from the head of the queue.
- Reinsertion of an mbuf at the head of the queue.
- Removal of the entire chain of mbufs on the queue.
- Insertion of the mbufs in an mbuf_list at the end of the queue.
- Removal of all the mbufs on the queue as an mbuf_list.
mq_init(struct mbuf_queue *mq, unsigned int maxlen, int ipl)- Initialises the mbuf queue structure mq. The maximum number of mbufs that should be queued is specified with maxlen. The highest interrupt priority level the queue will be operated at is specified via ipl.
MBUF_QUEUE_INITIALIZER(unsigned int maxlen, int ipl)- Initialises an mbuf queue structure declaration. The maximum number of mbufs that should be queued is specified with maxlen. The highest interrupt priority level the queue will be operated at is specified via ipl.
mq_enqueue(struct mbuf_queue *mq, struct mbuf *m)- Enqueue mbuf m on the end of the mq mbuf queue. If the queue is full then m will be dropped.
mq_push(struct mbuf_queue *mq, struct mbuf *m)- Enqueue mbuf m on the end of the mq mbuf queue. If the queue is full then the mbuf at the head of the queue will be dropped.
mq_dequeue(struct mbuf_queue *mq)- Dequeue an mbuf from the front of the mq mbuf queue.
mq_enlist(struct mbuf_queue *mq, struct mbuf_list *ml)- Enqueue all the mbufs on the ml mbuf list on to the end of the mq mbuf queue. Note, the number of mbufs placed on the queue may exceed its maximum length.
mq_delist(struct mbuf_queue *mq, struct mbuf_list *ml)- Dequeue all the mbufs on the mq mbuf queue on to the ml mbuf list.
mq_dechain(struct mbuf_queue *mq)- Dequeue all mbufs from the mq mbuf queue.
mq_len(struct mbuf_queue *mq)- Return the number of mbufs on the mq mbuf queue.
mq_empty(struct mbuf_queue *mq)- Return if the mq mbuf queue is empty.
mq_full(struct mbuf_queue *mq)- Return if the mq mbuf queue is full.
mq_hdatalen(struct mbuf_queue *mq)- Return the number of bytes in the packet at the head of the mq mbuf queue.
mq_purge(struct mbuf_queue *mq)- Free all the mbufs on the mq mbuf queue.
mq_drops(struct mbuf_queue *mq)- Return how many mbufs were dropped and freed by m_freem(9) if the mq mbuf queue was too full.
mq_set_maxlen(struct mbuf_queue *mq, unsigned int)- Alter the maximum number of mbufs that should be queued on the
mq mbuf queue. Note,
mq_set_maxlen() will only set a new limit, it will not free any excess mbufs that may already exist on the queue.
CONTEXT
mq_init(),
mq_enqueue(), mq_push(),
mq_dequeue(), mq_enlist(),
mq_delist(), mq_dechain(),
mq_len(), mq_empty(),
mq_full(), mq_purge(),
mq_drops(), mq_set_maxlen(),
and MBUF_QUEUE_INITIALIZER() can be called during
autoconf, from process context, or from interrupt context.
RETURN VALUES
mq_dequeue() returns the mbuf that was at
the head of its queue. If the queue was empty, NULL
is returned.
mq_dechain() returns all the mbufs that
were on its queues via a pointer to an mbuf with the chain accessible via
m_nextpkt members. If the queue was empty, NULL is
returned.
mq_len() returns the number of mbufs on
the queue.
mq_empty() returns a non-zero value if the
queue is empty, otherwise 0.
mq_full() returns a non-zero value if the
queue is full, otherwise 0.
mq_enqueue() returns 0 if the mbuf was
successfully queued, or non-zero if the mbuf was freed because it would
cause the queue to exceed its maximum length.
mq_push() returns 0 if there was space on
the queue for the mbuf, or non-zero if the head of the queue was freed to
make space for it.
mq_enlist() returns the number of mbufs
that were dropped from the list if the length of the queue exceeded its
maximum length.
mq_hdatalen() returns the size of a packet
on the queue, or 0 if the queue is empty.
mq_purge() returns the number of mbufs
that were freed.
mq_drops() returns the number of mbufs
that were freed during mq_enqueue() operations that
would have caused the queue to exceed its maximum length.