/* nm_sync callback for the monitor's own rx rings.
* Note that the lock in netmap_monitor_parent_sync only protects
* writers among themselves. Synchronization between writers
* (i.e., netmap_monitor_parent_txsync and netmap_monitor_parent_rxsync)
* and readers (i.e., netmap_monitor_rxsync) relies on memory barriers.
*/
static int
netmap_monitor_rxsync(struct netmap_kring *kring, int flags)
{
ND("%s %x", kring->name, flags);
kring->nr_hwcur = kring->rcur;
rmb();
nm_rxsync_finalize(kring);
return 0;
}
static int
netmap_pipe_rxsync(struct netmap_kring *rxkring, int flags)
{
struct netmap_kring *txkring = rxkring->pipe;
uint32_t oldhwcur = rxkring->nr_hwcur;
ND("%s %x <- %s", rxkring->name, flags, txkring->name);
rxkring->nr_hwcur = rxkring->rhead; /* recover user-relased slots */
ND(5, "hwcur %d hwtail %d cur %d head %d tail %d", rxkring->nr_hwcur, rxkring->nr_hwtail,
rxkring->rcur, rxkring->rhead, rxkring->rtail);
rmb(); /* paired with the first wmb() in txsync */
nm_rxsync_finalize(rxkring);
if (oldhwcur != rxkring->nr_hwcur) {
/* we have released some slots, notify the other end */
wmb(); /* make sure nr_hwcur is updated before notifying */
txkring->na->nm_notify(txkring->na, txkring->ring_id, NR_TX, 0);
}
return 0;
}