Commit daeaf55a authored by Guenter Roeck's avatar Guenter Roeck Committed by Ben Hutchings

usb: hub: Fix error loop seen after hub communication errors

commit 245b2eec upstream.

While stress testing a usb controller using a bind/unbind looop, the
following error loop was observed.

usb 7-1.2: new low-speed USB device number 3 using xhci-hcd
usb 7-1.2: hub failed to enable device, error -108
usb 7-1-port2: cannot disable (err = -22)
usb 7-1-port2: couldn't allocate usb_device
usb 7-1-port2: cannot disable (err = -22)
hub 7-1:1.0: hub_ext_port_status failed (err = -22)
hub 7-1:1.0: hub_ext_port_status failed (err = -22)
hub 7-1:1.0: activate --> -22
hub 7-1:1.0: hub_ext_port_status failed (err = -22)
hub 7-1:1.0: hub_ext_port_status failed (err = -22)
hub 7-1:1.0: activate --> -22
hub 7-1:1.0: hub_ext_port_status failed (err = -22)
hub 7-1:1.0: hub_ext_port_status failed (err = -22)
hub 7-1:1.0: activate --> -22
hub 7-1:1.0: hub_ext_port_status failed (err = -22)
hub 7-1:1.0: hub_ext_port_status failed (err = -22)
hub 7-1:1.0: activate --> -22
hub 7-1:1.0: hub_ext_port_status failed (err = -22)
hub 7-1:1.0: hub_ext_port_status failed (err = -22)
hub 7-1:1.0: activate --> -22
hub 7-1:1.0: hub_ext_port_status failed (err = -22)
hub 7-1:1.0: hub_ext_port_status failed (err = -22)
hub 7-1:1.0: activate --> -22
hub 7-1:1.0: hub_ext_port_status failed (err = -22)
hub 7-1:1.0: hub_ext_port_status failed (err = -22)
hub 7-1:1.0: activate --> -22
hub 7-1:1.0: hub_ext_port_status failed (err = -22)
hub 7-1:1.0: hub_ext_port_status failed (err = -22)
hub 7-1:1.0: activate --> -22
hub 7-1:1.0: hub_ext_port_status failed (err = -22)
hub 7-1:1.0: hub_ext_port_status failed (err = -22)
** 57 printk messages dropped ** hub 7-1:1.0: activate --> -22
** 82 printk messages dropped ** hub 7-1:1.0: hub_ext_port_status failed (err = -22)

This continues forever. After adding tracebacks into the code,
the call sequence leading to this is found to be as follows.

[<ffffffc0007fc8e0>] hub_activate+0x368/0x7b8
[<ffffffc0007fceb4>] hub_resume+0x2c/0x3c
[<ffffffc00080b3b8>] usb_resume_interface.isra.6+0x128/0x158
[<ffffffc00080b5d0>] usb_suspend_both+0x1e8/0x288
[<ffffffc00080c9c4>] usb_runtime_suspend+0x3c/0x98
[<ffffffc0007820a0>] __rpm_callback+0x48/0x7c
[<ffffffc00078217c>] rpm_callback+0xa8/0xd4
[<ffffffc000786234>] rpm_suspend+0x84/0x758
[<ffffffc000786ca4>] rpm_idle+0x2c8/0x498
[<ffffffc000786ed4>] __pm_runtime_idle+0x60/0xac
[<ffffffc00080eba8>] usb_autopm_put_interface+0x6c/0x7c
[<ffffffc000803798>] hub_event+0x10ac/0x12ac
[<ffffffc000249bb8>] process_one_work+0x390/0x6b8
[<ffffffc00024abcc>] worker_thread+0x480/0x610
[<ffffffc000251a80>] kthread+0x164/0x178
[<ffffffc0002045d0>] ret_from_fork+0x10/0x40

kick_hub_wq() is called from hub_activate() even after failures to
communicate with the hub. This results in an endless sequence of
hub event -> hub activate -> wq trigger -> hub event -> ...

Provide two solutions for the problem.

- Only trigger the hub event queue if communication with the hub
  is successful.
- After a suspend failure, only resume already suspended interfaces
  if the communication with the device is still possible.

Each of the changes fixes the observed problem. Use both to improve
robustness.
Acked-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
parent 7698ed67
...@@ -1331,6 +1331,24 @@ static int usb_suspend_both(struct usb_device *udev, pm_message_t msg) ...@@ -1331,6 +1331,24 @@ static int usb_suspend_both(struct usb_device *udev, pm_message_t msg)
*/ */
if (udev->parent && !PMSG_IS_AUTO(msg)) if (udev->parent && !PMSG_IS_AUTO(msg))
status = 0; status = 0;
/*
* If the device is inaccessible, don't try to resume
* suspended interfaces and just return the error.
*/
if (status && status != -EBUSY) {
int err;
u16 devstat;
err = usb_get_status(udev, USB_RECIP_DEVICE, 0,
&devstat);
if (err) {
dev_err(&udev->dev,
"Failed to suspend device, error %d\n",
status);
goto done;
}
}
} }
/* If the suspend failed, resume interfaces that did get suspended */ /* If the suspend failed, resume interfaces that did get suspended */
......
...@@ -1044,6 +1044,9 @@ static void hub_activate(struct usb_hub *hub, enum hub_activation_type type) ...@@ -1044,6 +1044,9 @@ static void hub_activate(struct usb_hub *hub, enum hub_activation_type type)
portstatus = portchange = 0; portstatus = portchange = 0;
status = hub_port_status(hub, port1, &portstatus, &portchange); status = hub_port_status(hub, port1, &portstatus, &portchange);
if (status)
goto abort;
if (udev || (portstatus & USB_PORT_STAT_CONNECTION)) if (udev || (portstatus & USB_PORT_STAT_CONNECTION))
dev_dbg(&port_dev->dev, "status %04x change %04x\n", dev_dbg(&port_dev->dev, "status %04x change %04x\n",
portstatus, portchange); portstatus, portchange);
...@@ -1176,7 +1179,7 @@ static void hub_activate(struct usb_hub *hub, enum hub_activation_type type) ...@@ -1176,7 +1179,7 @@ static void hub_activate(struct usb_hub *hub, enum hub_activation_type type)
/* Scan all ports that need attention */ /* Scan all ports that need attention */
kick_khubd(hub); kick_khubd(hub);
abort:
/* Allow autosuspend if it was suppressed */ /* Allow autosuspend if it was suppressed */
if (type <= HUB_INIT3) if (type <= HUB_INIT3)
usb_autopm_put_interface_async(to_usb_interface(hub->intfdev)); usb_autopm_put_interface_async(to_usb_interface(hub->intfdev));
......
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