From f3dec4452043a9ba3ea828f6bb3a38196fc46bbb Mon Sep 17 00:00:00 2001 From: Koen Vandeputte Date: Thu, 11 Jan 2018 16:04:37 +0100 Subject: [PATCH] cns3xxx: fix ethernet IRQ imbalance in 4.14 Kernel 4.14 contains more warnings regarding NAPI usage, which showed following warning: [ 4016.420000] ------------[ cut here ]------------ [ 4016.430000] WARNING: CPU: 1 PID: 14 at kernel/irq/manage.c:525 __enable_irq+0x3c/0x78 [ 4016.440000] Unbalanced enable for IRQ 51 [ 4016.440000] Modules linked in: ath9k ath9k_common pppoe ppp_async ath9k_hw ath pppox ppp_generic nf_conntrack_ipv6 mac80211 iptable_nat ipt_REJECT ipt_MASQUERADE cfg80211 xt_time xt_tcpudp xt_state xt_nat xt_multiport xt_mark xt_mac xt_limit xt_conntrack xt_comment xt_TCPMSS xt_REDIRECT xt_LOG slhc nf_reject_ipv4 nf_nat_redirs [ 4016.500000] CPU: 1 PID: 14 Comm: ksoftirqd/1 Tainted: G W 4.14.11 #0 [ 4016.500000] Hardware name: Gateworks Corporation Laguna Platform [ 4016.510000] Backtrace: [ 4016.510000] [] (dump_backtrace) from [] (show_stack+0x18/0x1c) [ 4016.520000] r7:c059df4b r6:00000000 r5:60000093 r4:00000000 [ 4016.530000] [] (show_stack) from [] (dump_stack+0x94/0xb4) [ 4016.530000] [] (dump_stack) from [] (__warn+0xc8/0xf8) [ 4016.540000] r7:c059df4b r6:c015144c r5:00000000 r4:cf863e08 [ 4016.550000] [] (__warn) from [] (warn_slowpath_fmt+0x40/0x48) [ 4016.550000] r9:cf863eb0 r8:00000036 r7:00000000 r6:c0636360 r5:00000033 r4:cf80a500 [ 4016.560000] [] (warn_slowpath_fmt) from [] (__enable_irq+0x3c/0x78) [ 4016.570000] r3:00000033 r2:c059e0c5 [ 4016.570000] [] (__enable_irq) from [] (enable_irq+0x64/0x7c) [ 4016.580000] [] (enable_irq) from [] (eth_poll+0x28c/0x558) [ 4016.590000] r5:d08926c0 r4:cf894488 [ 4016.590000] [] (eth_poll) from [] (net_rx_action+0xfc/0x2e8) [ 4016.600000] r10:cf863eb8 r9:cf863eb0 r8:00000001 r7:0f7b5000 r6:c0636360 r5:cfdeb360 [ 4016.610000] r4:cf894488 [ 4016.610000] [] (net_rx_action) from [] (__do_softirq+0xe0/0x228) [ 4016.620000] r10:00000100 r9:c070204c r8:c0702040 r7:00000003 r6:00000008 r5:40000003 [ 4016.620000] r4:cf862000 [ 4016.630000] [] (__do_softirq) from [] (run_ksoftirqd+0x34/0x58) [ 4016.630000] r10:c0133964 r9:00000000 r8:00000001 r7:00000000 r6:c070b44c r5:cf862000 [ 4016.640000] r4:cf8037e0 [ 4016.640000] [] (run_ksoftirqd) from [] (smpboot_thread_fn+0x178/0x190) [ 4016.650000] [] (smpboot_thread_fn) from [] (kthread+0x11c/0x138) [ 4016.660000] r9:cf8037e0 r8:cf802cdc r7:cf839df8 r6:cf803800 r5:00000000 r4:cf802cc0 [ 4016.670000] [] (kthread) from [] (ret_from_fork+0x14/0x3c) [ 4016.680000] r10:00000000 r9:00000000 r8:00000000 r7:00000000 r6:00000000 r5:c0130880 [ 4016.680000] r4:cf803800 r3:cf862000 [ 4016.690000] ---[ end trace 51114df08f429115 ]--- This is triggered by calling eth_schedule_poll(sw) after the IRQ has been re-enabled. Rework the network code to only enable IRQ's again if NAPI agrees it's safe to do so. Also only re-enable IRQ *after* cleaning up the RX ring and re-enabling DMA, which otherwise resulted in ugly warnings regarding dirty page fragments. These popped up nearly immediately when building the kernel with O2 iso Os. --> Note that this change fixes stability issues, at the cost of ~8% throughput performance. While at it, also change the iface name being used in warning prints, making it more obvious: "switch%d" --> "cns3xxx_eth" The changes have been tested on 4 boards, each moving ~30TB of data Signed-off-by: Koen Vandeputte --- .../140-fix-ethernet-irq-imbalance.patch | 77 +++++++++++++++++++ 1 file changed, 77 insertions(+) create mode 100644 target/linux/cns3xxx/patches-4.14/140-fix-ethernet-irq-imbalance.patch diff --git a/target/linux/cns3xxx/patches-4.14/140-fix-ethernet-irq-imbalance.patch b/target/linux/cns3xxx/patches-4.14/140-fix-ethernet-irq-imbalance.patch new file mode 100644 index 0000000000..3538586f6f --- /dev/null +++ b/target/linux/cns3xxx/patches-4.14/140-fix-ethernet-irq-imbalance.patch @@ -0,0 +1,77 @@ +--- a/drivers/net/ethernet/cavium/cns3xxx_eth.c ++++ b/drivers/net/ethernet/cavium/cns3xxx_eth.c +@@ -712,26 +712,20 @@ static int eth_poll(struct napi_struct * + } + + rx_ring->cur_index = i; +- if (!received) { +- napi_complete(napi); +- enable_irq(sw->rx_irq); +- budget = 0; +- +- /* If 1 or more frames came in during IRQ enable, re-schedule */ +- if (rx_ring->desc[i].cown) +- eth_schedule_poll(sw); +- } +- +- spin_lock_bh(&tx_lock); +- eth_complete_tx(sw); +- spin_unlock_bh(&tx_lock); + + cns3xxx_alloc_rx_buf(sw, received); +- + wmb(); + enable_rx_dma(sw); + +- return budget; ++ if (received < budget && napi_complete_done(napi, received)) { ++ enable_irq(sw->rx_irq); ++ } ++ ++ spin_lock_bh(&tx_lock); ++ eth_complete_tx(sw); ++ spin_unlock_bh(&tx_lock); ++ ++ return received; + } + + static void eth_set_desc(struct sw *sw, struct _tx_ring *tx_ring, int index, +@@ -856,18 +850,6 @@ static void cns3xxx_get_drvinfo(struct n + strcpy(info->bus_info, "internal"); + } + +-static int cns3xxx_get_settings(struct net_device *dev, struct ethtool_cmd *cmd) +-{ +- struct port *port = netdev_priv(dev); +- return phy_ethtool_gset(port->phydev, cmd); +-} +- +-static int cns3xxx_set_settings(struct net_device *dev, struct ethtool_cmd *cmd) +-{ +- struct port *port = netdev_priv(dev); +- return phy_ethtool_sset(port->phydev, cmd); +-} +- + static int cns3xxx_nway_reset(struct net_device *dev) + { + struct port *port = netdev_priv(dev); +@@ -876,8 +858,8 @@ static int cns3xxx_nway_reset(struct net + + static struct ethtool_ops cns3xxx_ethtool_ops = { + .get_drvinfo = cns3xxx_get_drvinfo, +- .get_settings = cns3xxx_get_settings, +- .set_settings = cns3xxx_set_settings, ++ .get_link_ksettings = phy_ethtool_get_link_ksettings, ++ .set_link_ksettings = phy_ethtool_set_link_ksettings, + .nway_reset = cns3xxx_nway_reset, + .get_link = ethtool_op_get_link, + }; +@@ -1177,7 +1159,7 @@ static int eth_init_one(struct platform_ + goto err_remove_mdio; + } + +- strcpy(napi_dev->name, "switch%d"); ++ strcpy(napi_dev->name, "cns3xxx_eth"); + napi_dev->features = NETIF_F_IP_CSUM | NETIF_F_SG | NETIF_F_FRAGLIST; + + SET_NETDEV_DEV(napi_dev, &pdev->dev);