Function reset_d

freebsd/net/bpf.c:1294–1320

* Reset a descriptor by flushing its packet buffer and clearing the receive * and drop counts. This is doable for kernel-only buffers, but with * zero-copy buffers, we can't write to (or rotate) buffers that are * currently owned by userspace. It would be nice if we could encapsulate * this logic in the buffer code rather than here. */

 * this logic in the buffer code rather than here.
 */
static void
reset_d(struct bpf_d *d)
{

	BPFD_LOCK_ASSERT(d);

	while (d->bd_hbuf_in_use)
		mtx_sleep(&d->bd_hbuf_in_use, &d->bd_lock, PRINET,
		    "bd_hbuf", 0);
	if ((d->bd_hbuf != NULL) &&
	    (d->bd_bufmode != BPF_BUFMODE_ZBUF || bpf_canfreebuf(d))) {
		/* Free the hold buffer. */
		d->bd_fbuf = d->bd_hbuf;
		d->bd_hbuf = NULL;
		d->bd_hlen = 0;
		bpf_buf_reclaimed(d);
	}
	if (bpf_canwritebuf(d))
		d->bd_slen = 0;
	counter_u64_zero(d->bd_rcount);
	counter_u64_zero(d->bd_dcount);
	counter_u64_zero(d->bd_fcount);
	counter_u64_zero(d->bd_wcount);
	counter_u64_zero(d->bd_wfcount);
	counter_u64_zero(d->bd_wdcount);
	counter_u64_zero(d->bd_zcopy);
}

/*
 *  FIONREAD		Check for read packet available.