[PATCH net-next 7/7] net: ethernet: mediatek: avoid race condition during the reset process

[sean.wang]

From: Sean Wang <sean.w...@mediatek.com>

add the protection of the race condition between
the reset process and hardware access happening
on the related callbacks.

Signed-off-by: Sean Wang <sean.w...@mediatek.com>
---
 drivers/net/ethernet/mediatek/mtk_eth_soc.c | 36 +++++++++++++++++++++++++++++
 drivers/net/ethernet/mediatek/mtk_eth_soc.h |  3 ++-
 2 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c 
b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
index 48cddf9..a6a9a2f 100644
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
@@ -145,6 +145,9 @@ static void mtk_phy_link_adjust(struct net_device *dev)
                  MAC_MCR_RX_EN | MAC_MCR_BACKOFF_EN |
                  MAC_MCR_BACKPR_EN;
 
+       if (unlikely(test_bit(MTK_RESETTING, &mac->hw->state)))
+               return;
+
        switch (mac->phy_dev->speed) {
        case SPEED_1000:
                mcr |= MAC_MCR_SPEED_1000;
@@ -370,6 +373,9 @@ static int mtk_set_mac_address(struct net_device *dev, void 
*p)
        if (ret)
                return ret;
 
+       if (unlikely(test_bit(MTK_RESETTING, &mac->hw->state)))
+               return -EBUSY;
+
        spin_lock_bh(&mac->hw->page_lock);
        mtk_w32(mac->hw, (macaddr[0] << 8) | macaddr[1],
                MTK_GDMA_MAC_ADRH(mac->id));
@@ -770,6 +776,9 @@ static int mtk_start_xmit(struct sk_buff *skb, struct 
net_device *dev)
         */
        spin_lock(&eth->page_lock);
 
+       if (unlikely(test_bit(MTK_RESETTING, &eth->state)))
+               goto drop;
+
        tx_num = mtk_cal_txd_req(skb);
        if (unlikely(atomic_read(&ring->free_count) <= tx_num)) {
                mtk_stop_queue(eth);
@@ -842,6 +851,9 @@ static int mtk_poll_rx(struct napi_struct *napi, int budget,
 
                netdev = eth->netdev[mac];
 
+               if (unlikely(test_bit(MTK_RESETTING, &eth->state)))
+                       goto release_desc;
+
                /* alloc new buffer */
                new_data = napi_alloc_frag(ring->frag_size);
                if (unlikely(!new_data)) {
@@ -1573,6 +1585,12 @@ static void mtk_pending_work(struct work_struct *work)
 
        rtnl_lock();
 
+       dev_dbg(eth->dev, "[%s][%d] reset\n", __func__, __LINE__);
+
+       while (test_and_set_bit_lock(MTK_RESETTING, &eth->state))
+               cpu_relax();
+
+       dev_dbg(eth->dev, "[%s][%d] mtk_stop starts\n", __func__, __LINE__);
        /* stop all devices to make sure that dma is properly shut down */
        for (i = 0; i < MTK_MAC_COUNT; i++) {
                if (!eth->netdev[i])
@@ -1580,6 +1598,7 @@ static void mtk_pending_work(struct work_struct *work)
                mtk_stop(eth->netdev[i]);
                __set_bit(i, &restart);
        }
+       dev_dbg(eth->dev, "[%s][%d] mtk_stop ends\n", __func__, __LINE__);
 
        /* restart underlying hardware such as power, clock, pin mux
         * and the connected phy
@@ -1613,6 +1632,11 @@ static void mtk_pending_work(struct work_struct *work)
                        dev_close(eth->netdev[i]);
                }
        }
+
+       dev_dbg(eth->dev, "[%s][%d] reset done\n", __func__, __LINE__);
+
+       clear_bit_unlock(MTK_RESETTING, &eth->state);
+
        rtnl_unlock();
 }
 
@@ -1657,6 +1681,9 @@ static int mtk_get_settings(struct net_device *dev,
        struct mtk_mac *mac = netdev_priv(dev);
        int err;
 
+       if (unlikely(test_bit(MTK_RESETTING, &mac->hw->state)))
+               return -EBUSY;
+
        err = phy_read_status(mac->phy_dev);
        if (err)
                return -ENODEV;
@@ -1707,6 +1734,9 @@ static int mtk_nway_reset(struct net_device *dev)
 {
        struct mtk_mac *mac = netdev_priv(dev);
 
+       if (unlikely(test_bit(MTK_RESETTING, &mac->hw->state)))
+               return -EBUSY;
+
        return genphy_restart_aneg(mac->phy_dev);
 }
 
@@ -1715,6 +1745,9 @@ static u32 mtk_get_link(struct net_device *dev)
        struct mtk_mac *mac = netdev_priv(dev);
        int err;
 
+       if (unlikely(test_bit(MTK_RESETTING, &mac->hw->state)))
+               return -EBUSY;
+
        err = genphy_update_link(mac->phy_dev);
        if (err)
                return ethtool_op_get_link(dev);
@@ -1755,6 +1788,9 @@ static void mtk_get_ethtool_stats(struct net_device *dev,
        unsigned int start;
        int i;
 
+       if (unlikely(test_bit(MTK_RESETTING, &mac->hw->state)))
+               return;
+
        if (netif_running(dev) && netif_device_present(dev)) {
                if (spin_trylock(&hwstats->stats_lock)) {
                        mtk_stats_update_mac(mac);
diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.h 
b/drivers/net/ethernet/mediatek/mtk_eth_soc.h
index 7efa00f..79954b4 100644
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.h
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.h
@@ -336,7 +336,8 @@ enum mtk_clks_map {
 };
 
 enum mtk_dev_state {
-       MTK_HW_INIT
+       MTK_HW_INIT,
+       MTK_RESETTING
 };
 
 /* struct mtk_tx_buf - This struct holds the pointers to the memory pointed at
-- 
1.9.1