From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752975AbaBLP4g (ORCPT ); Wed, 12 Feb 2014 10:56:36 -0500 Received: from mail-ea0-f174.google.com ([209.85.215.174]:41221 "EHLO mail-ea0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752847AbaBLP4e (ORCPT ); Wed, 12 Feb 2014 10:56:34 -0500 From: Michal Simek To: netdev@vger.kernel.org Cc: Srikanth Thokala , Peter Crosthwaite , Michal Simek , Anirudha Sarangi , John Linn , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH 04/14] net: axienet: Handle 0 packet receive gracefully Date: Wed, 12 Feb 2014 16:55:38 +0100 Message-Id: X-Mailer: git-send-email 1.8.2.3 In-Reply-To: References: In-Reply-To: References: Content-Type: multipart/signed; boundary="=_mimegpg-monstr-desktop-2235-1392220587-0001"; micalg=pgp-sha1; protocol="application/pgp-signature" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is a MIME GnuPG-signed message. If you see this text, it means that your E-mail or Usenet software does not support MIME signed messages. The Internet standard for MIME PGP messages, RFC 2015, was published in 1996. To open this message correctly you will need to install E-mail or Usenet software that supports modern Internet standards. --=_mimegpg-monstr-desktop-2235-1392220587-0001 From: Peter Crosthwaite The AXI-DMA rx-delay interrupt can sometimes be triggered when there are 0 outstanding packets received. This is due to the fact that the receive function will greedily consume as many packets as possible on interrupt. So if two packets (with a very particular timing) arrive in succession they will each cause the rx-delay interrupt, but the first interrupt will consume both packets. This means the second interrupt is a 0 packet receive. This is mostly OK, except that the tail pointer register is updated unconditionally on receive. Currently the tail pointer is always set to the current bd-ring descriptor under the assumption that the hardware has moved onto the next descriptor. What this means for length 0 recv is the current descriptor that the hardware is potentially yet to use will be marked as the tail. This causes the hardware to think its run out of descriptors deadlocking the whole rx path. Fixed by updating the tail pointer to the most recent successfully consumed descriptor. Reported-by: Wendy Liang Signed-off-by: Peter Crosthwaite Signed-off-by: Michal Simek Acked-by: Michal Simek Tested-by: Jason Wu --- drivers/net/ethernet/xilinx/xilinx_axienet_main.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c index 3966d83..2e21ab2 100644 --- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c +++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c @@ -726,15 +726,15 @@ static void axienet_recv(struct net_device *ndev) u32 csumstatus; u32 size = 0; u32 packets = 0; - dma_addr_t tail_p; + dma_addr_t tail_p = 0; struct axienet_local *lp = netdev_priv(ndev); struct sk_buff *skb, *new_skb; struct axidma_bd *cur_p; - tail_p = lp->rx_bd_p + sizeof(*lp->rx_bd_v) * lp->rx_bd_ci; cur_p = &lp->rx_bd_v[lp->rx_bd_ci]; while ((cur_p->status & XAXIDMA_BD_STS_COMPLETE_MASK)) { + tail_p = lp->rx_bd_p + sizeof(*lp->rx_bd_v) * lp->rx_bd_ci; skb = (struct sk_buff *) (cur_p->sw_id_offset); length = cur_p->app4 & 0x0000FFFF; @@ -786,7 +786,8 @@ static void axienet_recv(struct net_device *ndev) ndev->stats.rx_packets += packets; ndev->stats.rx_bytes += size; - axienet_dma_out32(lp, XAXIDMA_RX_TDESC_OFFSET, tail_p); + if (tail_p) + axienet_dma_out32(lp, XAXIDMA_RX_TDESC_OFFSET, tail_p); } /** -- 1.8.2.3 --=_mimegpg-monstr-desktop-2235-1392220587-0001 Content-Type: application/pgp-signature Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (GNU/Linux) iEYEABECAAYFAlL7masACgkQykllyylKDCHe1wCfQUMhGx7DTCtBek6lIDac22QN K40AoJfnMuFWIlp0LQOLH3lJVMZBsLct =9aDv -----END PGP SIGNATURE----- --=_mimegpg-monstr-desktop-2235-1392220587-0001--