Full barriers order the preceding index store against the following load of the interrupt mask or pending size and stay seq_cst; read barriers become acquire fences. Same code generated on x86 and arm64.
The write barrier before publishing the transmit index becomes a release fence. Nominally stronger on arm64, but it is immediately followed by a full barrier cmpset; converting that to a release compare-exchange is left for the rte_atomic32 removal series. Signed-off-by: Stephen Hemminger <[email protected]> --- drivers/bus/vmbus/vmbus_bufring.c | 6 +++--- drivers/bus/vmbus/vmbus_channel.c | 6 +++--- 2 files changed, 6 insertions(+), 6 deletions(-) diff --git a/drivers/bus/vmbus/vmbus_bufring.c b/drivers/bus/vmbus/vmbus_bufring.c index f622869974..31478d3bfa 100644 --- a/drivers/bus/vmbus/vmbus_bufring.c +++ b/drivers/bus/vmbus/vmbus_bufring.c @@ -58,11 +58,11 @@ void vmbus_br_setup(struct vmbus_br *br, void *buf, unsigned int blen) static inline bool vmbus_txbr_need_signal(const struct vmbus_bufring *vbr, uint32_t old_windex) { - rte_smp_mb(); + rte_atomic_thread_fence(rte_memory_order_seq_cst); if (vbr->imask) return false; - rte_smp_rmb(); + rte_atomic_thread_fence(rte_memory_order_acquire); /* * This is the only case we need to signal when the @@ -158,7 +158,7 @@ vmbus_txbr_write(struct vmbus_br *tbr, const struct iovec iov[], int iovlen, RTE_ASSERT(windex == next_windex); /* Ensure that data is available before updating host index */ - rte_smp_wmb(); + rte_atomic_thread_fence(rte_memory_order_release); /* Checkin for our reservation. wait for our turn to update host */ while (!rte_atomic32_cmpset(&vbr->windex, old_windex, next_windex)) diff --git a/drivers/bus/vmbus/vmbus_channel.c b/drivers/bus/vmbus/vmbus_channel.c index 2648d8e3fd..10293f59be 100644 --- a/drivers/bus/vmbus/vmbus_channel.c +++ b/drivers/bus/vmbus/vmbus_channel.c @@ -211,7 +211,7 @@ bool rte_vmbus_chan_rx_empty(const struct vmbus_channel *channel) { const struct vmbus_br *br = &channel->rxbr; - rte_smp_rmb(); + rte_atomic_thread_fence(rte_memory_order_acquire); return br->vbr->rindex == br->vbr->windex; } @@ -229,13 +229,13 @@ void rte_vmbus_chan_signal_read(struct rte_vmbus_device *dev, return; /* Make sure reading of pending happens after new read index */ - rte_smp_mb(); + rte_atomic_thread_fence(rte_memory_order_seq_cst); pending_sz = rbr->vbr->pending_send; if (!pending_sz) return; - rte_smp_rmb(); + rte_atomic_thread_fence(rte_memory_order_acquire); write_sz = vmbus_br_availwrite(rbr, rbr->vbr->windex); /* If there was space before then host was not blocked */ -- 2.53.0
