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DRBR(9) FreeBSD Kernel Developer's Manual DRBR(9)
NAME
drbr, drbr_free, drbr_enqueue, drbr_dequeue, drbr_dequeue_cond,
drbr_flush, drbr_empty, drbr_inuse - network driver interface to buf_ring
SYNOPSIS
#include <sys/param.h>
#include <net/if.h>
#include <net/if_var.h>
void
drbr_free(struct buf_ring *br, struct malloc_type *type);
int
drbr_enqueue(struct ifnet *ifp, struct buf_ring *br, struct mbuf *m);
struct mbuf *
drbr_dequeue(struct ifnet *ifp, struct buf_ring *br);
struct mbuf *
drbr_dequeue_cond(struct ifnet *ifp, struct buf_ring *br,
int (*func) (struct mbuf *, void *), void *arg);
void
drbr_flush(struct ifnet *ifp, struct buf_ring *br);
int
drbr_empty(struct ifnet *ifp, struct buf_ring *br);
int
drbr_inuse(struct ifnet *ifp, struct buf_ring *br);
DESCRIPTION
The drbr functions provide an API to network drivers for using
buf_ring(9) for enqueueing and dequeueing packets. This is meant as a
replacement for the IFQ interface for packet queuing. It allows a packet
to be enqueued with a single atomic and packet dequeue to be done without
any per-packet atomics as it is protected by the driver's tx queue lock.
If INVARIANTS is enabled, drbr_dequeue() will assert that the tx queue
lock is held when it is called.
The drbr_free() function frees all the enqueued mbufs and then frees the
buf_ring.
The drbr_enqueue() function is used to enqueue an mbuf to a buf_ring,
falling back to the ifnet's IFQ if ALTQ(4) is enabled.
The drbr_dequeue() function is used to dequeue an mbuf from a buf_ring
or, if ALTQ(4) is enabled, from the ifnet's IFQ.
The drbr_dequeue_cond() function is used to conditionally dequeue an mbuf
from a buf_ring based on whether func returns TRUE or FALSE.
The drbr_flush() function frees all mbufs enqueued in the buf_ring and
the ifnet's IFQ.
The drbr_empty() function returns TRUE if there are no mbufs enqueued,
FALSE otherwise.
The drbr_enqueue() function returns ENOBUFS if there are no slots
available in the buf_ring and 0 on success.
The drbr_dequeue() and drbr_dequeue_cond() functions return an mbuf on
success and NULL if the buf_ring is empty.
HISTORY
These functions were introduced in FreeBSD 8.0.
FreeBSD 14.0-RELEASE-p11 September 27, 2012 FreeBSD 14.0-RELEASE-p11