From 306a27825c54e840bc33db924878fe6ef2a2be4f Mon Sep 17 00:00:00 2001 From: Ben Hutchings Date: Fri, 28 Jun 2013 21:47:15 +0100 Subject: [PATCH] sfc: Separate out queue-empty check from efx_nic_may_push_tx_desc() Signed-off-by: Ben Hutchings --- drivers/net/ethernet/sfc/nic.h | 28 ++++++++++++++++++++++------ 1 file changed, 22 insertions(+), 6 deletions(-) diff --git a/drivers/net/ethernet/sfc/nic.h b/drivers/net/ethernet/sfc/nic.h index db70005999c3..609f06769245 100644 --- a/drivers/net/ethernet/sfc/nic.h +++ b/drivers/net/ethernet/sfc/nic.h @@ -71,6 +71,26 @@ efx_tx_desc(struct efx_tx_queue *tx_queue, unsigned int index) return ((efx_qword_t *) (tx_queue->txd.buf.addr)) + index; } +/* Report whether the NIC considers this TX queue empty, given the + * write_count used for the last doorbell push. May return false + * negative. + */ +static inline bool __efx_nic_tx_is_empty(struct efx_tx_queue *tx_queue, + unsigned int write_count) +{ + unsigned int empty_read_count = ACCESS_ONCE(tx_queue->empty_read_count); + + if (empty_read_count == 0) + return false; + + return ((empty_read_count ^ write_count) & ~EFX_EMPTY_COUNT_VALID) == 0; +} + +static inline bool efx_nic_tx_is_empty(struct efx_tx_queue *tx_queue) +{ + return __efx_nic_tx_is_empty(tx_queue, tx_queue->write_count); +} + /* Decide whether to push a TX descriptor to the NIC vs merely writing * the doorbell. This can reduce latency when we are adding a single * descriptor to an empty queue, but is otherwise pointless. Further, @@ -80,14 +100,10 @@ efx_tx_desc(struct efx_tx_queue *tx_queue, unsigned int index) static inline bool efx_nic_may_push_tx_desc(struct efx_tx_queue *tx_queue, unsigned int write_count) { - unsigned empty_read_count = ACCESS_ONCE(tx_queue->empty_read_count); - - if (empty_read_count == 0) - return false; + bool was_empty = __efx_nic_tx_is_empty(tx_queue, write_count); tx_queue->empty_read_count = 0; - return ((empty_read_count ^ write_count) & ~EFX_EMPTY_COUNT_VALID) == 0 - && tx_queue->write_count - write_count == 1; + return was_empty && tx_queue->write_count - write_count == 1; } /* Returns a pointer to the specified descriptor in the RX descriptor queue */ -- 2.39.5