From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755700AbdKGBKk (ORCPT ); Mon, 6 Nov 2017 20:10:40 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:52511 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755231AbdKFXyJ (ORCPT ); Mon, 6 Nov 2017 18:54:09 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "David S. Miller" , "Florian Fainelli" , "Jaedon Shin" , "Petri Gynther" Date: Mon, 06 Nov 2017 23:03:02 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 012/294] net: bcmgenet: rewrite bcmgenet_rx_refill() In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.50-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Petri Gynther commit d6707bec598649450ee0887bf11896e525777874 upstream. Currently, bcmgenet_desc_rx() calls bcmgenet_rx_refill() at the end of Rx packet processing loop, after the current Rx packet has already been passed to napi_gro_receive(). However, bcmgenet_rx_refill() might fail to allocate a new Rx skb, thus leaving a hole on the Rx queue where no valid Rx buffer exists. To eliminate this situation: 1. Rewrite bcmgenet_rx_refill() to retain the current Rx skb on the Rx queue if a new replacement Rx skb can't be allocated and DMA-mapped. In this case, the data on the current Rx skb is effectively dropped. 2. Modify bcmgenet_desc_rx() to call bcmgenet_rx_refill() at the top of Rx packet processing loop, so that the new replacement Rx skb is already in place before the current Rx skb is processed. Signed-off-by: Petri Gynther Tested-by: Jaedon Shin -- Reviewed-by: Florian Fainelli Tested-by: Florian Fainelli Signed-off-by: David S. Miller [bwh: Backported to 3.16: - There's no alloc_rx_buff_failed statistic - Adjust context] Signed-off-by: Ben Hutchings --- --- a/drivers/net/ethernet/broadcom/genet/bcmgenet.c +++ b/drivers/net/ethernet/broadcom/genet/bcmgenet.c @@ -1275,33 +1275,41 @@ out: return ret; } - -static int bcmgenet_rx_refill(struct bcmgenet_priv *priv, - struct enet_cb *cb) +static struct sk_buff *bcmgenet_rx_refill(struct bcmgenet_priv *priv, + struct enet_cb *cb) { struct device *kdev = &priv->pdev->dev; struct sk_buff *skb; + struct sk_buff *rx_skb; dma_addr_t mapping; - int ret; + /* Allocate a new Rx skb */ skb = netdev_alloc_skb(priv->dev, priv->rx_buf_len + SKB_ALIGNMENT); - if (!skb) - return -ENOMEM; + if (!skb) { + netif_err(priv, rx_err, priv->dev, + "%s: Rx skb allocation failed\n", __func__); + return NULL; + } - /* a caller did not release this control block */ - WARN_ON(cb->skb != NULL); - cb->skb = skb; - mapping = dma_map_single(kdev, skb->data, - priv->rx_buf_len, DMA_FROM_DEVICE); - ret = dma_mapping_error(kdev, mapping); - if (ret) { - bcmgenet_free_cb(cb); + /* DMA-map the new Rx skb */ + mapping = dma_map_single(kdev, skb->data, priv->rx_buf_len, + DMA_FROM_DEVICE); + if (dma_mapping_error(kdev, mapping)) { + dev_kfree_skb_any(skb); netif_err(priv, rx_err, priv->dev, - "%s DMA map failed\n", __func__); - return ret; + "%s: Rx skb DMA mapping failed\n", __func__); + return NULL; } + /* Grab the current Rx skb from the ring and DMA-unmap it */ + rx_skb = cb->skb; + if (likely(rx_skb)) + dma_unmap_single(kdev, dma_unmap_addr(cb, dma_addr), + priv->rx_buf_len, DMA_FROM_DEVICE); + + /* Put the new Rx skb on the ring */ + cb->skb = skb; dma_unmap_addr_set(cb, dma_addr, mapping); /* assign packet, prepare descriptor, and advance pointer */ @@ -1314,7 +1322,8 @@ static int bcmgenet_rx_refill(struct bcm priv->rx_bd_assign_ptr = priv->rx_bds + (priv->rx_bd_assign_index * DMA_DESC_SIZE); - return 0; + /* Return the current Rx skb to caller */ + return rx_skb; } /* bcmgenet_desc_rx - descriptor based rx process. @@ -1329,7 +1338,7 @@ static unsigned int bcmgenet_desc_rx(str struct sk_buff *skb; u32 dma_length_status; unsigned long dma_flag; - int len, err; + int len; unsigned int rxpktprocessed = 0, rxpkttoprocess; unsigned int p_index; unsigned int chksum_ok = 0; @@ -1351,26 +1360,14 @@ static unsigned int bcmgenet_desc_rx(str (rxpktprocessed < budget)) { cb = &priv->rx_cbs[priv->rx_read_ptr]; - skb = cb->skb; + skb = bcmgenet_rx_refill(priv, cb); - /* We do not have a backing SKB, so we do not have a - * corresponding DMA mapping for this incoming packet since - * bcmgenet_rx_refill always either has both skb and mapping or - * none. - */ if (unlikely(!skb)) { dev->stats.rx_dropped++; dev->stats.rx_errors++; - goto refill; + goto next; } - /* Unmap the packet contents such that we can use the - * RSV from the 64 bytes descriptor when enabled and save - * a 32-bits register read - */ - dma_unmap_single(kdev, dma_unmap_addr(cb, dma_addr), - priv->rx_buf_len, DMA_FROM_DEVICE); - if (!priv->desc_64b_en) { dma_length_status = dmadesc_get_length_status(priv, priv->rx_bds + @@ -1398,10 +1395,10 @@ static unsigned int bcmgenet_desc_rx(str "Droping fragmented packet!\n"); dev->stats.rx_dropped++; dev->stats.rx_errors++; - dev_kfree_skb_any(cb->skb); - cb->skb = NULL; - goto refill; + dev_kfree_skb_any(skb); + goto next; } + /* report errors */ if (unlikely(dma_flag & (DMA_RX_CRC_ERROR | DMA_RX_OV | @@ -1420,11 +1417,8 @@ static unsigned int bcmgenet_desc_rx(str dev->stats.rx_length_errors++; dev->stats.rx_dropped++; dev->stats.rx_errors++; - - /* discard the packet and advance consumer index.*/ - dev_kfree_skb_any(cb->skb); - cb->skb = NULL; - goto refill; + dev_kfree_skb_any(skb); + goto next; } /* error packet */ chksum_ok = (dma_flag & priv->dma_rx_chk_bit) && @@ -1457,15 +1451,9 @@ static unsigned int bcmgenet_desc_rx(str /* Notify kernel */ napi_gro_receive(&priv->napi, skb); - cb->skb = NULL; netif_dbg(priv, rx_status, dev, "pushed up to kernel\n"); - /* refill RX path on the current control block */ -refill: - err = bcmgenet_rx_refill(priv, cb); - if (err) - netif_err(priv, rx_err, dev, "Rx refill failed\n"); - +next: rxpktprocessed++; priv->rx_read_ptr++; priv->rx_read_ptr &= (priv->num_rx_bds - 1); @@ -1478,7 +1466,7 @@ refill: static int bcmgenet_alloc_rx_buffers(struct bcmgenet_priv *priv) { struct enet_cb *cb; - int ret = 0; + struct sk_buff *skb; int i; netif_dbg(priv, hw, priv->dev, "%s:\n", __func__); @@ -1486,16 +1474,14 @@ static int bcmgenet_alloc_rx_buffers(str /* loop here for each buffer needing assign */ for (i = 0; i < priv->num_rx_bds; i++) { cb = &priv->rx_cbs[priv->rx_bd_assign_index]; - if (cb->skb) - continue; - - ret = bcmgenet_rx_refill(priv, cb); - if (ret) - break; - + skb = bcmgenet_rx_refill(priv, cb); + if (skb) + dev_kfree_skb_any(skb); + if (!cb->skb) + return -ENOMEM; } - return ret; + return 0; } static void bcmgenet_free_rx_buffers(struct bcmgenet_priv *priv)