Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757767Ab2EGTaT (ORCPT ); Mon, 7 May 2012 15:30:19 -0400 Received: from mail-ee0-f46.google.com ([74.125.83.46]:38850 "EHLO mail-ee0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753964Ab2EGTaR (ORCPT ); Mon, 7 May 2012 15:30:17 -0400 Message-ID: <4FA822C4.60809@gmail.com> Date: Mon, 07 May 2012 21:30:12 +0200 From: Erwan Velu User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.4) Gecko/20120426 Thunderbird/10.0.4 MIME-Version: 1.0 To: netdev@vger.kernel.org, linux-kernel@vger.kernel.org CC: tshimizu818@gmail.com Subject: [PATCH] pch_gbe: Adding read memory barriers Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2239 Lines: 57 From bb1e271db0fa1a29df19bede69faf8004389132d Mon Sep 17 00:00:00 2001 From: Erwan Velu Date: Mon, 7 May 2012 19:15:29 +0000 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 issue. Getting it into stable would be perfect as it solves reliability issues. Signed-off-by: Erwan Velu --- .../net/ethernet/oki-semi/pch_gbe/pch_gbe_main.c | 3 +++ 1 files changed, 3 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 8035e5f..ace3654 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 @@ -1413,6 +1413,7 @@ static irqreturn_t pch_gbe_intr(int irq, void *data) pch_gbe_mac_set_pause_packet(hw); } } + 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)) || @@ -1582,6 +1584,7 @@ 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); @@ -1682,6 +1685,7 @@ 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; -- 1.7.3.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/