From patchwork Wed Dec 9 08:37:40 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Giuseppe CAVALLARO X-Patchwork-Id: 554272 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 7F81914018C for ; Wed, 9 Dec 2015 19:28:19 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753354AbbLII2N (ORCPT ); Wed, 9 Dec 2015 03:28:13 -0500 Received: from mx07-00178001.pphosted.com ([62.209.51.94]:11965 "EHLO mx07-00178001.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753265AbbLII2J (ORCPT ); Wed, 9 Dec 2015 03:28:09 -0500 Received: from pps.filterd (m0046037.ppops.net [127.0.0.1]) by m0046037.ppops.net (8.14.5/8.14.5) with SMTP id tB98Bmho031140 for ; Wed, 9 Dec 2015 09:28:07 +0100 Received: from beta.dmz-eu.st.com (beta.dmz-eu.st.com [164.129.1.35]) by m0046037.ppops.net with ESMTP id 1ynn3af6y8-1 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NOT) for ; Wed, 09 Dec 2015 09:28:07 +0100 Received: from zeta.dmz-eu.st.com (zeta.dmz-eu.st.com [164.129.230.9]) by beta.dmz-eu.st.com (STMicroelectronics) with ESMTP id BF94742 for ; Wed, 9 Dec 2015 08:27:30 +0000 (GMT) Received: from Webmail-eu.st.com (Safex1hubcas21.st.com [10.75.90.44]) by zeta.dmz-eu.st.com (STMicroelectronics) with ESMTP id 2145A4F0C for ; Wed, 9 Dec 2015 08:28:06 +0000 (GMT) Received: from localhost (164.130.129.175) by Webmail-ga.st.com (10.75.90.48) with Microsoft SMTP Server (TLS) id 14.3.235.1; Wed, 9 Dec 2015 09:28:05 +0100 From: Giuseppe Cavallaro To: CC: , Giuseppe Cavallaro , David McKay Subject: [PATCH (net-next.git) 04/18] stmmac: remove modulo in stmmac_xmit() Date: Wed, 9 Dec 2015 09:37:40 +0100 Message-ID: <1449650274-14896-5-git-send-email-peppe.cavallaro@st.com> X-Mailer: git-send-email 1.7.4.4 In-Reply-To: <1449650274-14896-1-git-send-email-peppe.cavallaro@st.com> References: <1449650274-14896-1-git-send-email-peppe.cavallaro@st.com> MIME-Version: 1.0 X-Originating-IP: [164.130.129.175] X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:5.15.21, 1.0.33, 0.0.0000 definitions=2015-12-09_05:2015-12-08, 2015-12-09, 1970-01-01 signatures=0 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org The indexes into the ring buffer are always incremented, and the entry is accessed via doing a modulo to find the "real" index. I have changed this for 3 reasons: * It is inefficient, modulo is an expensive operation. * It is also broken when the counter wraps. * It makes my head hurt trying to cope with huge numbers This patch replaces the modulo with a simple if clamp. Signed-off-by: David McKay Signed-off-by: Giuseppe Cavallaro --- drivers/net/ethernet/stmicro/stmmac/chain_mode.c | 15 ++++++---- drivers/net/ethernet/stmicro/stmmac/ring_mode.c | 7 +++- drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 31 +++++++++++++++----- 3 files changed, 37 insertions(+), 16 deletions(-) diff --git a/drivers/net/ethernet/stmicro/stmmac/chain_mode.c b/drivers/net/ethernet/stmicro/stmmac/chain_mode.c index cf28dab..399a7ed 100644 --- a/drivers/net/ethernet/stmicro/stmmac/chain_mode.c +++ b/drivers/net/ethernet/stmicro/stmmac/chain_mode.c @@ -32,7 +32,7 @@ static int stmmac_jumbo_frm(void *p, struct sk_buff *skb, int csum) { struct stmmac_priv *priv = (struct stmmac_priv *)p; unsigned int txsize = priv->dma_tx_size; - unsigned int entry = priv->cur_tx % txsize; + unsigned int entry = priv->cur_tx; struct dma_desc *desc = priv->dma_tx + entry; unsigned int nopaged_len = skb_headlen(skb); unsigned int bmax; @@ -54,7 +54,8 @@ static int stmmac_jumbo_frm(void *p, struct sk_buff *skb, int csum) while (len != 0) { priv->tx_skbuff[entry] = NULL; - entry = (++priv->cur_tx) % txsize; + if (++entry >= txsize) + entry = 0; desc = priv->dma_tx + entry; if (len > bmax) { @@ -82,6 +83,9 @@ static int stmmac_jumbo_frm(void *p, struct sk_buff *skb, int csum) len = 0; } } + + priv->cur_tx = entry; + return entry; } @@ -151,10 +155,9 @@ static void stmmac_clean_desc3(void *priv_ptr, struct dma_desc *p) * 1588-2002 time stamping is enabled, hence reinitialize it * to keep explicit chaining in the descriptor. */ - p->des3 = (unsigned int)(priv->dma_tx_phy + - (((priv->dirty_tx + 1) % - priv->dma_tx_size) * - sizeof(struct dma_desc))); + p->des3 = (unsigned int)((priv->dma_tx_phy + + priv->dirty_tx + 1) * + sizeof(struct dma_desc)); } const struct stmmac_mode_ops chain_mode_ops = { diff --git a/drivers/net/ethernet/stmicro/stmmac/ring_mode.c b/drivers/net/ethernet/stmicro/stmmac/ring_mode.c index 5dd50c6..2560855 100644 --- a/drivers/net/ethernet/stmicro/stmmac/ring_mode.c +++ b/drivers/net/ethernet/stmicro/stmmac/ring_mode.c @@ -32,7 +32,7 @@ static int stmmac_jumbo_frm(void *p, struct sk_buff *skb, int csum) { struct stmmac_priv *priv = (struct stmmac_priv *)p; unsigned int txsize = priv->dma_tx_size; - unsigned int entry = priv->cur_tx % txsize; + unsigned int entry = priv->cur_tx; struct dma_desc *desc; unsigned int nopaged_len = skb_headlen(skb); unsigned int bmax, len; @@ -62,7 +62,8 @@ static int stmmac_jumbo_frm(void *p, struct sk_buff *skb, int csum) STMMAC_RING_MODE); wmb(); priv->tx_skbuff[entry] = NULL; - entry = (++priv->cur_tx) % txsize; + if (++entry >= txsize) + entry = 0; if (priv->extend_desc) desc = (struct dma_desc *)(priv->dma_etx + entry); @@ -90,6 +91,8 @@ static int stmmac_jumbo_frm(void *p, struct sk_buff *skb, int csum) STMMAC_RING_MODE); } + priv->cur_tx = entry; + return entry; } diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c index 2dd0279..366da1f 100644 --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c @@ -201,7 +201,14 @@ static void print_pkt(unsigned char *buf, int len) static inline u32 stmmac_tx_avail(struct stmmac_priv *priv) { - return priv->dirty_tx + priv->dma_tx_size - priv->cur_tx - 1; + unsigned avail; + + if (priv->dirty_tx > priv->cur_tx) + avail = priv->dirty_tx - priv->cur_tx - 1; + else + avail = priv->dma_tx_size - priv->cur_tx + priv->dirty_tx - 1; + + return avail; } /** @@ -1315,16 +1322,16 @@ static void stmmac_dma_operation_mode(struct stmmac_priv *priv) */ static void stmmac_tx_clean(struct stmmac_priv *priv) { - unsigned int txsize = priv->dma_tx_size; unsigned int bytes_compl = 0, pkts_compl = 0; + unsigned int txsize = priv->dma_tx_size; + unsigned int entry = priv->dirty_tx; spin_lock(&priv->tx_lock); priv->xstats.tx_clean++; - while (priv->dirty_tx != priv->cur_tx) { + while (entry != priv->cur_tx) { int last; - unsigned int entry = priv->dirty_tx % txsize; struct sk_buff *skb = priv->tx_skbuff[entry]; struct dma_desc *p; @@ -1381,7 +1388,9 @@ static void stmmac_tx_clean(struct stmmac_priv *priv) priv->hw->desc->release_tx_desc(p, priv->mode); - priv->dirty_tx++; + if (++entry >= txsize) + entry = 0; + priv->dirty_tx = entry; } netdev_completed_queue(priv->dev, pkts_compl, bytes_compl); @@ -1981,7 +1990,8 @@ static netdev_tx_t stmmac_xmit(struct sk_buff *skb, struct net_device *dev) if (priv->tx_path_in_lpi_mode) stmmac_disable_eee_mode(priv); - entry = priv->cur_tx % txsize; + entry = priv->cur_tx; + csum_insertion = (skb->ip_summed == CHECKSUM_PARTIAL); @@ -2016,7 +2026,9 @@ static netdev_tx_t stmmac_xmit(struct sk_buff *skb, struct net_device *dev) int len = skb_frag_size(frag); priv->tx_skbuff[entry] = NULL; - entry = (++priv->cur_tx) % txsize; + if (++entry >= txsize) + entry = 0; + if (priv->extend_desc) desc = (struct dma_desc *)(priv->dma_etx + entry); else @@ -2059,7 +2071,10 @@ static netdev_tx_t stmmac_xmit(struct sk_buff *skb, struct net_device *dev) priv->hw->desc->set_tx_owner(first); wmb(); - priv->cur_tx++; + if (++entry >= txsize) + entry = 0; + + priv->cur_tx = entry; if (netif_msg_pktdata(priv)) { pr_debug("%s: curr %d dirty=%d entry=%d, first=%p, nfrags=%d",