/*
* NOTE:
* We assume (dlen + skip) == sizeof(channel packet).
*/
int
vmbus_rxbr_read(struct vmbus_rxbr *rbr, void *data, int dlen, uint32_t skip)
{
uint32_t rindex, br_dsize = rbr->rxbr_dsize;
KASSERT(dlen + skip > 0, ("invalid dlen %d, offset %u", dlen, skip));
mtx_lock_spin(&rbr->rxbr_lock);
if (vmbus_rxbr_avail(rbr) < dlen + skip + sizeof(uint64_t)) {
mtx_unlock_spin(&rbr->rxbr_lock);
return (EAGAIN);
}
/*
* Copy channel packet from RX bufring.
*/
rindex = VMBUS_BR_IDXINC(rbr->rxbr_rindex, skip, br_dsize);
rindex = vmbus_rxbr_copyfrom(rbr, rindex, data, dlen);
/*
* Discard this channel packet's 64bits offset, which is useless to us.
*/
rindex = VMBUS_BR_IDXINC(rindex, sizeof(uint64_t), br_dsize);
/*
* Update the read index _after_ the channel packet is fetched.
*/
__compiler_membar();
rbr->rxbr_rindex = rindex;
mtx_unlock_spin(&rbr->rxbr_lock);
return (0);
}
/*
* Copy data from receive ring and change index
* NOTE:
* We assume (dlen + skip) == sizeof(channel packet).
*/
int
vmbus_rxbr_read(struct vmbus_br *rbr, void *data, size_t dlen, size_t skip)
{
struct vmbus_bufring *vbr = rbr->vbr;
uint32_t br_dsize = rbr->dsize;
uint32_t rindex;
if (vmbus_br_availread(rbr) < dlen + skip + sizeof(uint64_t))
return -EAGAIN;
/* Record where host was when we started read (for debug) */
rbr->windex = rbr->vbr->windex;
/*
* Copy channel packet from RX bufring.
*/
rindex = vmbus_br_idxinc(rbr->vbr->rindex, skip, br_dsize);
rindex = vmbus_rxbr_copyfrom(rbr, rindex, data, dlen);
/*
* Discard this channel packet's 64bits offset, which is useless to us.
*/
rindex = vmbus_br_idxinc(rindex, sizeof(uint64_t), br_dsize);
/* Update the read index _after_ the channel packet is fetched. */
rte_compiler_barrier();
vbr->rindex = rindex;
return 0;
}
/* Copy data from receive ring but don't change index */
int
vmbus_rxbr_peek(const struct vmbus_br *rbr, void *data, size_t dlen)
{
uint32_t avail;
/*
* The requested data and the 64bits channel packet
* offset should be there at least.
*/
avail = vmbus_br_availread(rbr);
if (avail < dlen + sizeof(uint64_t))
return -EAGAIN;
vmbus_rxbr_copyfrom(rbr, rbr->vbr->rindex, data, dlen);
return 0;
}
int
vmbus_rxbr_peek(struct vmbus_rxbr *rbr, void *data, int dlen)
{
mtx_lock_spin(&rbr->rxbr_lock);
/*
* The requested data and the 64bits channel packet
* offset should be there at least.
*/
if (vmbus_rxbr_avail(rbr) < dlen + sizeof(uint64_t)) {
mtx_unlock_spin(&rbr->rxbr_lock);
return (EAGAIN);
}
vmbus_rxbr_copyfrom(rbr, rbr->rxbr_rindex, data, dlen);
mtx_unlock_spin(&rbr->rxbr_lock);
return (0);
}
