This is a note to let you know that I've just added the patch titled
usb: hub: Fix error loop seen after hub communication errors
to my usb git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-next branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will also be merged in the next major kernel release
during the merge window.
If you have any questions about this process, please let me know.
>From 245b2eecee2aac6fdc77dcafaa73c33f9644c3c7 Mon Sep 17 00:00:00 2001
From: Guenter Roeck <linux@xxxxxxxxxxxx>
Date: Mon, 20 Mar 2017 11:16:11 -0700
Subject: usb: hub: Fix error loop seen after hub communication errors
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: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Cc: stable <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/usb/core/driver.c | 18 ++++++++++++++++++
drivers/usb/core/hub.c | 5 ++++-
2 files changed, 22 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
index cdee5130638b..7ebdf2a4e8fe 100644
--- a/drivers/usb/core/driver.c
+++ b/drivers/usb/core/driver.c
@@ -1331,6 +1331,24 @@ static int usb_suspend_both(struct usb_device *udev, pm_message_t msg)
*/
if (udev->parent && !PMSG_IS_AUTO(msg))
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 */
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index f0dd08198d74..735e8ab2cc1f 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -1066,6 +1066,9 @@ static void hub_activate(struct usb_hub *hub, enum hub_activation_type type)
portstatus = portchange = 0;
status = hub_port_status(hub, port1, &portstatus, &portchange);
+ if (status)
+ goto abort;
+
if (udev || (portstatus & USB_PORT_STAT_CONNECTION))
dev_dbg(&port_dev->dev, "status %04x change %04x\n",
portstatus, portchange);
@@ -1198,7 +1201,7 @@ static void hub_activate(struct usb_hub *hub, enum hub_activation_type type)
/* Scan all ports that need attention */
kick_hub_wq(hub);
-
+ abort:
if (type == HUB_INIT2 || type == HUB_INIT3) {
/* Allow autosuspend if it was suppressed */
disconnected:
--
2.12.1