From 124b74c18e0e31b24638d256afee7122a994e1b3 Mon Sep 17 00:00:00 2001 From: Alexander Duyck Date: Thu, 11 Dec 2014 15:02:28 -0800 Subject: [PATCH] fm10k/igb/ixgbe: Use dma_rmb on Rx descriptor reads This change makes it so that dma_rmb is used when reading the Rx descriptor. The advantage of dma_rmb is that it allows for a much lower cost barrier on x86, powerpc, arm, and arm64 architectures than a traditional memory barrier when dealing with reads that only have to synchronize to coherent memory. In addition I have updated the code so that it just checks to see if any bits have been set instead of just the DD bit since the DD bit will always be set as a part of a descriptor write-back so we just need to check for a non-zero value being present at that memory location rather than just checking for any specific bit. This allows the code itself to appear much cleaner and allows the compiler more room to optimize. Cc: Matthew Vick Cc: Don Skidmore Acked-by: Jeff Kirsher Signed-off-by: Alexander Duyck Signed-off-by: David S. Miller --- drivers/net/ethernet/intel/fm10k/fm10k_main.c | 6 +++--- drivers/net/ethernet/intel/igb/igb_main.c | 6 +++--- drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 9 ++++----- 3 files changed, 10 insertions(+), 11 deletions(-) diff --git a/drivers/net/ethernet/intel/fm10k/fm10k_main.c b/drivers/net/ethernet/intel/fm10k/fm10k_main.c index ee1ecb146df7..eb088b129bc7 100644 --- a/drivers/net/ethernet/intel/fm10k/fm10k_main.c +++ b/drivers/net/ethernet/intel/fm10k/fm10k_main.c @@ -615,14 +615,14 @@ static bool fm10k_clean_rx_irq(struct fm10k_q_vector *q_vector, rx_desc = FM10K_RX_DESC(rx_ring, rx_ring->next_to_clean); - if (!fm10k_test_staterr(rx_desc, FM10K_RXD_STATUS_DD)) + if (!rx_desc->d.staterr) break; /* This memory barrier is needed to keep us from reading * any other fields out of the rx_desc until we know the - * RXD_STATUS_DD bit is set + * descriptor has been written back */ - rmb(); + dma_rmb(); /* retrieve a buffer from the ring */ skb = fm10k_fetch_rx_buffer(rx_ring, rx_desc, skb); diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c index 2e526d4904a6..ff59897a9463 100644 --- a/drivers/net/ethernet/intel/igb/igb_main.c +++ b/drivers/net/ethernet/intel/igb/igb_main.c @@ -6910,14 +6910,14 @@ static bool igb_clean_rx_irq(struct igb_q_vector *q_vector, const int budget) rx_desc = IGB_RX_DESC(rx_ring, rx_ring->next_to_clean); - if (!igb_test_staterr(rx_desc, E1000_RXD_STAT_DD)) + if (!rx_desc->wb.upper.status_error) break; /* This memory barrier is needed to keep us from reading * any other fields out of the rx_desc until we know the - * RXD_STAT_DD bit is set + * descriptor has been written back */ - rmb(); + dma_rmb(); /* retrieve a buffer from the ring */ skb = igb_fetch_rx_buffer(rx_ring, rx_desc, skb); diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c index 798b05556e1b..2ed2c7de2304 100644 --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c @@ -2009,15 +2009,14 @@ static int ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector, rx_desc = IXGBE_RX_DESC(rx_ring, rx_ring->next_to_clean); - if (!ixgbe_test_staterr(rx_desc, IXGBE_RXD_STAT_DD)) + if (!rx_desc->wb.upper.status_error) break; - /* - * This memory barrier is needed to keep us from reading + /* This memory barrier is needed to keep us from reading * any other fields out of the rx_desc until we know the - * RXD_STAT_DD bit is set + * descriptor has been written back */ - rmb(); + dma_rmb(); /* retrieve a buffer from the ring */ skb = ixgbe_fetch_rx_buffer(rx_ring, rx_desc); -- 2.20.1