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94 lines
3.1 KiB
Diff
94 lines
3.1 KiB
Diff
From 6f152b2bdb295d86beb746494ef6fddf17986f8e Mon Sep 17 00:00:00 2001
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From: John Crispin <blogic@openwrt.org>
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Date: Tue, 29 Mar 2016 17:20:01 +0200
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Subject: [PATCH 067/102] net: mediatek: fix TX locking
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Inside the TX path there is a lock inside the tx_map function. This is
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however too late. The patch moves the lock to the start of the xmit
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function right before the free count check of the DMA ring happens.
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If we do not do this, the code becomes racy leading to TX stalls and
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dropped packets. This happens as there are 2 netdevs running on the
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same physical DMA ring.
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Signed-off-by: John Crispin <blogic@openwrt.org>
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---
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drivers/net/ethernet/mediatek/mtk_eth_soc.c | 20 ++++++++++----------
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1 file changed, 10 insertions(+), 10 deletions(-)
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--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
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+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
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@@ -536,7 +536,6 @@ static int mtk_tx_map(struct sk_buff *sk
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struct mtk_eth *eth = mac->hw;
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struct mtk_tx_dma *itxd, *txd;
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struct mtk_tx_buf *tx_buf;
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- unsigned long flags;
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dma_addr_t mapped_addr;
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unsigned int nr_frags;
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int i, n_desc = 1;
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@@ -568,11 +567,6 @@ static int mtk_tx_map(struct sk_buff *sk
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if (unlikely(dma_mapping_error(&dev->dev, mapped_addr)))
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return -ENOMEM;
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- /* normally we can rely on the stack not calling this more than once,
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- * however we have 2 queues running ont he same ring so we need to lock
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- * the ring access
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- */
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- spin_lock_irqsave(ð->page_lock, flags);
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WRITE_ONCE(itxd->txd1, mapped_addr);
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tx_buf->flags |= MTK_TX_FLAGS_SINGLE0;
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dma_unmap_addr_set(tx_buf, dma_addr0, mapped_addr);
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@@ -632,8 +626,6 @@ static int mtk_tx_map(struct sk_buff *sk
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WRITE_ONCE(itxd->txd3, (TX_DMA_SWC | TX_DMA_PLEN0(skb_headlen(skb)) |
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(!nr_frags * TX_DMA_LS0)));
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- spin_unlock_irqrestore(ð->page_lock, flags);
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-
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netdev_sent_queue(dev, skb->len);
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skb_tx_timestamp(skb);
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@@ -661,8 +653,6 @@ err_dma:
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itxd = mtk_qdma_phys_to_virt(ring, itxd->txd2);
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} while (itxd != txd);
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- spin_unlock_irqrestore(ð->page_lock, flags);
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-
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return -ENOMEM;
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}
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@@ -712,14 +702,22 @@ static int mtk_start_xmit(struct sk_buff
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struct mtk_eth *eth = mac->hw;
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struct mtk_tx_ring *ring = ð->tx_ring;
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struct net_device_stats *stats = &dev->stats;
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+ unsigned long flags;
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bool gso = false;
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int tx_num;
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+ /* normally we can rely on the stack not calling this more than once,
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+ * however we have 2 queues running ont he same ring so we need to lock
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+ * the ring access
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+ */
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+ spin_lock_irqsave(ð->page_lock, flags);
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+
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tx_num = mtk_cal_txd_req(skb);
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if (unlikely(atomic_read(&ring->free_count) <= tx_num)) {
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mtk_stop_queue(eth);
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netif_err(eth, tx_queued, dev,
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"Tx Ring full when queue awake!\n");
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+ spin_unlock_irqrestore(ð->page_lock, flags);
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return NETDEV_TX_BUSY;
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}
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@@ -747,10 +745,12 @@ static int mtk_start_xmit(struct sk_buff
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ring->thresh))
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mtk_wake_queue(eth);
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}
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+ spin_unlock_irqrestore(ð->page_lock, flags);
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return NETDEV_TX_OK;
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drop:
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+ spin_unlock_irqrestore(ð->page_lock, flags);
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stats->tx_dropped++;
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dev_kfree_skb(skb);
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return NETDEV_TX_OK;
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