queue-4.4/usbnet-ipheth-prevent-tx-queue-timeouts-when-device-not-ready.patch

   1 From bb1b40c7cb863f0800a6410c7dcb86cf3f28d3b1 Mon Sep 17 00:00:00 2001
   2 From: Alexander Kappner <agk@godking.net>
   3 Date: Mon, 13 Nov 2017 17:44:20 -0800
   4 Subject: usbnet: ipheth: prevent TX queue timeouts when device not ready
   5
   6 From: Alexander Kappner <agk@godking.net>
   7
   8 commit bb1b40c7cb863f0800a6410c7dcb86cf3f28d3b1 upstream.
   9
  10 iOS devices require the host to be "trusted" before servicing network
  11 packets. Establishing trust requires the user to confirm a dialog on the
  12 iOS device.Until trust is established, the iOS device will silently discard
  13 network packets from the host. Currently, the ipheth driver does not detect
  14 whether an iOS device has established trust with the host, and immediately
  15 sets up the transmit queues.
  16
  17 This causes the following problems:
  18
  19 - Kernel taint due to WARN() in netdev watchdog.
  20 - Dmesg spam ("TX timeout").
  21 - Disruption of user space networking activity (dhcpd, etc...) when new
  22 interface comes up but cannot be used.
  23 - Unnecessary host and device wakeups and USB traffic
  24
  25 Example dmesg output:
  26
  27 [ 1101.319778] NETDEV WATCHDOG: eth1 (ipheth): transmit queue 0 timed out
  28 [ 1101.319817] ------------[ cut here ]------------
  29 [ 1101.319828] WARNING: CPU: 0 PID: 0 at net/sched/sch_generic.c:316 dev_watchdog+0x20f/0x220
  30 [ 1101.319831] Modules linked in: ipheth usbmon nvidia_drm(PO) nvidia_modeset(PO) nvidia(PO) iwlmvm mac80211 iwlwifi btusb btrtl btbcm btintel qmi_wwan bluetooth cfg80211 ecdh_generic thinkpad_acpi rfkill [last unloaded: ipheth]
  31 [ 1101.319861] CPU: 0 PID: 0 Comm: swapper/0 Tainted: P           O    4.13.12.1 #1
  32 [ 1101.319864] Hardware name: LENOVO 20ENCTO1WW/20ENCTO1WW, BIOS N1EET62W (1.35 ) 11/10/2016
  33 [ 1101.319867] task: ffffffff81e11500 task.stack: ffffffff81e00000
  34 [ 1101.319873] RIP: 0010:dev_watchdog+0x20f/0x220
  35 [ 1101.319876] RSP: 0018:ffff8810a3c03e98 EFLAGS: 00010292
  36 [ 1101.319880] RAX: 000000000000003a RBX: 0000000000000000 RCX: 0000000000000000
  37 [ 1101.319883] RDX: ffff8810a3c15c48 RSI: ffffffff81ccbfc2 RDI: 00000000ffffffff
  38 [ 1101.319886] RBP: ffff880c04ebc41c R08: 0000000000000000 R09: 0000000000000379
  39 [ 1101.319889] R10: 00000100696589d0 R11: 0000000000000378 R12: ffff880c04ebc000
  40 [ 1101.319892] R13: 0000000000000000 R14: 0000000000000001 R15: ffff880c2865fc80
  41 [ 1101.319896] FS:  0000000000000000(0000) GS:ffff8810a3c00000(0000) knlGS:0000000000000000
  42 [ 1101.319899] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  43 [ 1101.319902] CR2: 00007f3ff24ac000 CR3: 0000000001e0a000 CR4: 00000000003406f0
  44 [ 1101.319905] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  45 [ 1101.319908] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  46 [ 1101.319910] Call Trace:
  47 [ 1101.319914]  <IRQ>
  48 [ 1101.319921]  ? dev_graft_qdisc+0x70/0x70
  49 [ 1101.319928]  ? dev_graft_qdisc+0x70/0x70
  50 [ 1101.319934]  ? call_timer_fn+0x2e/0x170
  51 [ 1101.319939]  ? dev_graft_qdisc+0x70/0x70
  52 [ 1101.319944]  ? run_timer_softirq+0x1ea/0x440
  53 [ 1101.319951]  ? timerqueue_add+0x54/0x80
  54 [ 1101.319956]  ? enqueue_hrtimer+0x38/0xa0
  55 [ 1101.319963]  ? __do_softirq+0xed/0x2e7
  56 [ 1101.319970]  ? irq_exit+0xb4/0xc0
  57 [ 1101.319976]  ? smp_apic_timer_interrupt+0x39/0x50
  58 [ 1101.319981]  ? apic_timer_interrupt+0x8c/0xa0
  59 [ 1101.319983]  </IRQ>
  60 [ 1101.319992]  ? cpuidle_enter_state+0xfa/0x2a0
  61 [ 1101.319999]  ? do_idle+0x1a3/0x1f0
  62 [ 1101.320004]  ? cpu_startup_entry+0x5f/0x70
  63 [ 1101.320011]  ? start_kernel+0x444/0x44c
  64 [ 1101.320017]  ? early_idt_handler_array+0x120/0x120
  65 [ 1101.320023]  ? x86_64_start_kernel+0x145/0x154
  66 [ 1101.320028]  ? secondary_startup_64+0x9f/0x9f
  67 [ 1101.320033] Code: 20 04 00 00 eb 9f 4c 89 e7 c6 05 59 44 71 00 01 e8 a7 df fd ff 89 d9 4c 89 e6 48 c7 c7 70 b7 cd 81 48 89 c2 31 c0 e8 97 64 90 ff <0f> ff eb bf 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00
  68 [ 1101.320103] ---[ end trace 0cc4d251e2b57080 ]---
  69 [ 1101.320110] ipheth 1-5:4.2: ipheth_tx_timeout: TX timeout
  70
  71 The last message "TX timeout" is repeated every 5 seconds until trust is
  72 established or the device is disconnected, filling up dmesg.
  73
  74 The proposed patch eliminates the problem by, upon connection, keeping the
  75 TX queue and carrier disabled until a packet is first received from the iOS
  76 device. This is reflected by the confirmed_pairing variable in the device
  77 structure. Only after at least one packet has been received from the iOS
  78 device, the transmit queue and carrier are brought up during the periodic
  79 device poll in ipheth_carrier_set. Because the iOS device will always send
  80 a packet immediately upon trust being established, this should not delay
  81 the interface becoming useable. To prevent failed UBRs in
  82 ipheth_rcvbulk_callback from perpetually re-enabling the queue if it was
  83 disabled, a new check is added so only successful transfers re-enable the
  84 queue, whereas failed transfers only trigger an immediate poll.
  85
  86 This has the added benefit of removing the periodic control requests to the
  87 iOS device until trust has been established and thus should reduce wakeup
  88 events on both the host and the iOS device.
  89
  90 Signed-off-by: Alexander Kappner <agk@godking.net>
  91 Signed-off-by: David S. Miller <davem@davemloft.net>
  92 [groeck: Fixed context conflict seen because 45611c61dd50 was applied first]
  93 Signed-off-by: Guenter Roeck <linux@roeck-us.net>
  94 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  95 ---
  96  drivers/net/usb/ipheth.c |   30 +++++++++++++++++++++---------
  97  1 file changed, 21 insertions(+), 9 deletions(-)
  98
  99 --- a/drivers/net/usb/ipheth.c
 100 +++ b/drivers/net/usb/ipheth.c
 101 @@ -148,6 +148,7 @@ struct ipheth_device {
 102         u8 bulk_in;
 103         u8 bulk_out;
 104         struct delayed_work carrier_work;
 105 +       bool confirmed_pairing;
 106  };
 107
 108  static int ipheth_rx_submit(struct ipheth_device *dev, gfp_t mem_flags);
 109 @@ -259,7 +260,7 @@ static void ipheth_rcvbulk_callback(stru
 110
 111         dev->net->stats.rx_packets++;
 112         dev->net->stats.rx_bytes += len;
 113 -
 114 +       dev->confirmed_pairing = true;
 115         netif_rx(skb);
 116         ipheth_rx_submit(dev, GFP_ATOMIC);
 117  }
 118 @@ -280,14 +281,21 @@ static void ipheth_sndbulk_callback(stru
 119                 dev_err(&dev->intf->dev, "%s: urb status: %d\n",
 120                 __func__, status);
 121
 122 -       netif_wake_queue(dev->net);
 123 +       if (status == 0)
 124 +               netif_wake_queue(dev->net);
 125 +       else
 126 +               // on URB error, trigger immediate poll
 127 +               schedule_delayed_work(&dev->carrier_work, 0);
 128  }
 129
 130  static int ipheth_carrier_set(struct ipheth_device *dev)
 131  {
 132         struct usb_device *udev = dev->udev;
 133         int retval;
 134 -
 135 +       if (!dev)
 136 +               return 0;
 137 +       if (!dev->confirmed_pairing)
 138 +               return 0;
 139         retval = usb_control_msg(udev,
 140                         usb_rcvctrlpipe(udev, IPHETH_CTRL_ENDP),
 141                         IPHETH_CMD_CARRIER_CHECK, /* request */
 142 @@ -302,11 +310,14 @@ static int ipheth_carrier_set(struct iph
 143                 return retval;
 144         }
 145
 146 -       if (dev->ctrl_buf[0] == IPHETH_CARRIER_ON)
 147 +       if (dev->ctrl_buf[0] == IPHETH_CARRIER_ON) {
 148                 netif_carrier_on(dev->net);
 149 -       else
 150 +               if (dev->tx_urb->status != -EINPROGRESS)
 151 +                       netif_wake_queue(dev->net);
 152 +       } else {
 153                 netif_carrier_off(dev->net);
 154 -
 155 +               netif_stop_queue(dev->net);
 156 +       }
 157         return 0;
 158  }
 159
 160 @@ -386,7 +397,6 @@ static int ipheth_open(struct net_device
 161                 return retval;
 162
 163         schedule_delayed_work(&dev->carrier_work, IPHETH_CARRIER_CHECK_TIMEOUT);
 164 -       netif_start_queue(net);
 165         return retval;
 166  }
 167
 168 @@ -489,7 +499,7 @@ static int ipheth_probe(struct usb_inter
 169         dev->udev = udev;
 170         dev->net = netdev;
 171         dev->intf = intf;
 172 -
 173 +       dev->confirmed_pairing = false;
 174         /* Set up endpoints */
 175         hintf = usb_altnum_to_altsetting(intf, IPHETH_ALT_INTFNUM);
 176         if (hintf == NULL) {
 177 @@ -540,7 +550,9 @@ static int ipheth_probe(struct usb_inter
 178                 retval = -EIO;
 179                 goto err_register_netdev;
 180         }
 181 -
 182 +       // carrier down and transmit queues stopped until packet from device
 183 +       netif_carrier_off(netdev);
 184 +       netif_tx_stop_all_queues(netdev);
 185         dev_info(&intf->dev, "Apple iPhone USB Ethernet device attached\n");
 186         return 0;
 187