releases/4.11.2/usb-hub-fix-error-loop-seen-after-hub-communication-errors.patch

   1 From 245b2eecee2aac6fdc77dcafaa73c33f9644c3c7 Mon Sep 17 00:00:00 2001
   2 From: Guenter Roeck <linux@roeck-us.net>
   3 Date: Mon, 20 Mar 2017 11:16:11 -0700
   4 Subject: usb: hub: Fix error loop seen after hub communication errors
   5
   6 From: Guenter Roeck <linux@roeck-us.net>
   7
   8 commit 245b2eecee2aac6fdc77dcafaa73c33f9644c3c7 upstream.
   9
  10 While stress testing a usb controller using a bind/unbind looop, the
  11 following error loop was observed.
  12
  13 usb 7-1.2: new low-speed USB device number 3 using xhci-hcd
  14 usb 7-1.2: hub failed to enable device, error -108
  15 usb 7-1-port2: cannot disable (err = -22)
  16 usb 7-1-port2: couldn't allocate usb_device
  17 usb 7-1-port2: cannot disable (err = -22)
  18 hub 7-1:1.0: hub_ext_port_status failed (err = -22)
  19 hub 7-1:1.0: hub_ext_port_status failed (err = -22)
  20 hub 7-1:1.0: activate --> -22
  21 hub 7-1:1.0: hub_ext_port_status failed (err = -22)
  22 hub 7-1:1.0: hub_ext_port_status failed (err = -22)
  23 hub 7-1:1.0: activate --> -22
  24 hub 7-1:1.0: hub_ext_port_status failed (err = -22)
  25 hub 7-1:1.0: hub_ext_port_status failed (err = -22)
  26 hub 7-1:1.0: activate --> -22
  27 hub 7-1:1.0: hub_ext_port_status failed (err = -22)
  28 hub 7-1:1.0: hub_ext_port_status failed (err = -22)
  29 hub 7-1:1.0: activate --> -22
  30 hub 7-1:1.0: hub_ext_port_status failed (err = -22)
  31 hub 7-1:1.0: hub_ext_port_status failed (err = -22)
  32 hub 7-1:1.0: activate --> -22
  33 hub 7-1:1.0: hub_ext_port_status failed (err = -22)
  34 hub 7-1:1.0: hub_ext_port_status failed (err = -22)
  35 hub 7-1:1.0: activate --> -22
  36 hub 7-1:1.0: hub_ext_port_status failed (err = -22)
  37 hub 7-1:1.0: hub_ext_port_status failed (err = -22)
  38 hub 7-1:1.0: activate --> -22
  39 hub 7-1:1.0: hub_ext_port_status failed (err = -22)
  40 hub 7-1:1.0: hub_ext_port_status failed (err = -22)
  41 hub 7-1:1.0: activate --> -22
  42 hub 7-1:1.0: hub_ext_port_status failed (err = -22)
  43 hub 7-1:1.0: hub_ext_port_status failed (err = -22)
  44 ** 57 printk messages dropped ** hub 7-1:1.0: activate --> -22
  45 ** 82 printk messages dropped ** hub 7-1:1.0: hub_ext_port_status failed (err = -22)
  46
  47 This continues forever. After adding tracebacks into the code,
  48 the call sequence leading to this is found to be as follows.
  49
  50 [<ffffffc0007fc8e0>] hub_activate+0x368/0x7b8
  51 [<ffffffc0007fceb4>] hub_resume+0x2c/0x3c
  52 [<ffffffc00080b3b8>] usb_resume_interface.isra.6+0x128/0x158
  53 [<ffffffc00080b5d0>] usb_suspend_both+0x1e8/0x288
  54 [<ffffffc00080c9c4>] usb_runtime_suspend+0x3c/0x98
  55 [<ffffffc0007820a0>] __rpm_callback+0x48/0x7c
  56 [<ffffffc00078217c>] rpm_callback+0xa8/0xd4
  57 [<ffffffc000786234>] rpm_suspend+0x84/0x758
  58 [<ffffffc000786ca4>] rpm_idle+0x2c8/0x498
  59 [<ffffffc000786ed4>] __pm_runtime_idle+0x60/0xac
  60 [<ffffffc00080eba8>] usb_autopm_put_interface+0x6c/0x7c
  61 [<ffffffc000803798>] hub_event+0x10ac/0x12ac
  62 [<ffffffc000249bb8>] process_one_work+0x390/0x6b8
  63 [<ffffffc00024abcc>] worker_thread+0x480/0x610
  64 [<ffffffc000251a80>] kthread+0x164/0x178
  65 [<ffffffc0002045d0>] ret_from_fork+0x10/0x40
  66
  67 kick_hub_wq() is called from hub_activate() even after failures to
  68 communicate with the hub. This results in an endless sequence of
  69 hub event -> hub activate -> wq trigger -> hub event -> ...
  70
  71 Provide two solutions for the problem.
  72
  73 - Only trigger the hub event queue if communication with the hub
  74   is successful.
  75 - After a suspend failure, only resume already suspended interfaces
  76   if the communication with the device is still possible.
  77
  78 Each of the changes fixes the observed problem. Use both to improve
  79 robustness.
  80
  81 Acked-by: Alan Stern <stern@rowland.harvard.edu>
  82 Signed-off-by: Guenter Roeck <linux@roeck-us.net>
  83 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  84
  85 ---
  86  drivers/usb/core/driver.c |   18 ++++++++++++++++++
  87  drivers/usb/core/hub.c    |    5 ++++-
  88  2 files changed, 22 insertions(+), 1 deletion(-)
  89
  90 --- a/drivers/usb/core/driver.c
  91 +++ b/drivers/usb/core/driver.c
  92 @@ -1331,6 +1331,24 @@ static int usb_suspend_both(struct usb_d
  93                  */
  94                 if (udev->parent && !PMSG_IS_AUTO(msg))
  95                         status = 0;
  96 +
  97 +               /*
  98 +                * If the device is inaccessible, don't try to resume
  99 +                * suspended interfaces and just return the error.
 100 +                */
 101 +               if (status && status != -EBUSY) {
 102 +                       int err;
 103 +                       u16 devstat;
 104 +
 105 +                       err = usb_get_status(udev, USB_RECIP_DEVICE, 0,
 106 +                                            &devstat);
 107 +                       if (err) {
 108 +                               dev_err(&udev->dev,
 109 +                                       "Failed to suspend device, error %d\n",
 110 +                                       status);
 111 +                               goto done;
 112 +                       }
 113 +               }
 114         }
 115
 116         /* If the suspend failed, resume interfaces that did get suspended */
 117 --- a/drivers/usb/core/hub.c
 118 +++ b/drivers/usb/core/hub.c
 119 @@ -1066,6 +1066,9 @@ static void hub_activate(struct usb_hub
 120
 121                 portstatus = portchange = 0;
 122                 status = hub_port_status(hub, port1, &portstatus, &portchange);
 123 +               if (status)
 124 +                       goto abort;
 125 +
 126                 if (udev || (portstatus & USB_PORT_STAT_CONNECTION))
 127                         dev_dbg(&port_dev->dev, "status %04x change %04x\n",
 128                                         portstatus, portchange);
 129 @@ -1198,7 +1201,7 @@ static void hub_activate(struct usb_hub
 130
 131         /* Scan all ports that need attention */
 132         kick_hub_wq(hub);
 133 -
 134 + abort:
 135         if (type == HUB_INIT2 || type == HUB_INIT3) {
 136                 /* Allow autosuspend if it was suppressed */
 137   disconnected: