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Date: Mon, 07 May 2012 19:49:58 +0200 From: Erwan Velu <erwanaliasr1@...il.com> To: netdev@...r.kernel.org, linux-kernel@...r.kernel.org CC: tshimizu818@...il.com Subject: [PATCH] pch_gbe: Adding read memory barriers From 3b65802e4c5a8827a84022066f10dec4d61c1f22 Mon Sep 17 00:00:00 2001 From: Erwan Velu <erwan.velu@...iacaerospace.com> Date: Mon, 7 May 2012 14:53:17 +0200 Subject: [PATCH 1/1] pch_gbe: Adding read memory barriers Under a strong incoming packet stream and/or high cpu usage, the pch_gbe driver reports "Receive CRC Error" and discards packet. It occurred on an Intel ATOM E620T while running a 300mbit/sec multicast network stream leading to a ~100% cpu usage. Adding rmb() calls before considering the network card's status solve this issues. This patch got validated on the 3.2.16 kernel but also apply to the 3.x family. Getting it into stable would be perfect as it solves reliability issues. Signed-off-by: Erwan Velu <erwan.velu@...iacaerospace.com> --- .../net/ethernet/oki-semi/pch_gbe/pch_gbe_main.c | 8 ++++++++ 1 files changed, 8 insertions(+), 0 deletions(-) diff --git a/drivers/net/ethernet/oki-semi/pch_gbe/pch_gbe_main.c b/drivers/net/ethernet/oki-semi/pch_gbe/pch_gbe_main.c index 48406ca..7746ca3 100644 --- a/drivers/net/ethernet/oki-semi/pch_gbe/pch_gbe_main.c +++ b/drivers/net/ethernet/oki-semi/pch_gbe/pch_gbe_main.c @@ -1222,6 +1222,8 @@ static irqreturn_t pch_gbe_intr(int irq, void *data) } } + smp_rmb(); /* prevent any other reads before*/ + /* When request status is Receive interruption */ if ((int_st & (PCH_GBE_INT_RX_DMA_CMPLT | PCH_GBE_INT_TX_CMPLT)) || (adapter->rx_stop_flag == true)) { @@ -1390,6 +1392,9 @@ pch_gbe_clean_tx(struct pch_gbe_adapter *adapter, i = tx_ring->next_to_clean; tx_desc = PCH_GBE_TX_DESC(*tx_ring, i); + + rmb(); /* prevent any other reads before*/ + pr_debug("gbec_status:0x%04x dma_status:0x%04x\n", tx_desc->gbec_status, tx_desc->dma_status); @@ -1490,6 +1495,9 @@ pch_gbe_clean_rx(struct pch_gbe_adapter *adapter, while (*work_done < work_to_do) { /* Check Rx descriptor status */ rx_desc = PCH_GBE_RX_DESC(*rx_ring, i); + + rmb(); /* prevent any other reads before*/ + if (rx_desc->gbec_status == DSC_INIT16) break; cleaned = true; -- 1.7.4.4 -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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