On Wed, Sep 25, 2019 at 10:20:00AM -0400, Alan Stern wrote:
> On Tue, 24 Sep 2019, David Heinzelmann wrote:
>
> > > I really don't understand this.
> > >
> > > Your patch involves the case where there was a connect-change event but
> > > the port is still enabled. Now maybe I've forgotten about one of the
> > > pathways, but it seems like that combination should never occur.
> > >
> > > Certainly it shouldn't occur in your case. The device disconnects and
> > > then reconnects with a new set of descriptors. The disconnect should
> > > cause the port to be disabled, and the port should remain disabled
> > > after the reconnect occurs. So how can your new code run in the first
> > > place?
> > >
> > > Alan Stern
> > >
> >
> > Hi,
> >
> > I have a log with two devices which are connected to a hub and the hub is plugged in.
> >
> > The device which is not working in this log:
> >
> > Sep 24 08:32:21 kernel: usb 2-6-port1: status 0203 change 0011
> > Sep 24 08:32:21 kernel: usb 2-6.1: new SuperSpeed Gen 1 USB device number 65 using xhci_hcd
>
> Ah, SuperSpeed. You're using a USB-3 device. That does make a
> difference.
>
> > Sep 24 08:32:21 kernel: usb 2-6.1: udev 65, busnum 2, minor = 192
> > Sep 24 08:32:21 kernel: usb 2-6.1: New USB device found, idVendor=1409, idProduct=3240, bcdDevice= 0.00
> > Sep 24 08:32:21 kernel: usb 2-6.1: New USB device strings: Mfr=1, Product=2, SerialNumber=0
> > Sep 24 08:32:21 kernel: usb 2-6.1: Product: USB 3.0 Camera
> > Sep 24 08:32:21 kernel: usb 2-6.1: Manufacturer: Camera Manufacturer
> >
> > Now the firmware download happens and the device is re-enumerating and a disconnect/connect should occur.
> > But the only change which is seen is the following output:
> >
> > Sep 24 08:32:23 kernel: usb 2-6-port1: link state change
> > Sep 24 08:32:23 kernel: usb 2-6-port1: status 0203, change 0041, 5.0 Gb/s
> >
> > Now the resuscitation is happening but from my understanding this is not correct as in the reality there was a
> > reconnect from the device. So I tried to initiate a device reconnect if the device descriptor changed.
> >
> > It also seems to me that the enumeration from the second device (usb 2-6-port1) is blocking
> > the port change event and so the actual disconnect is missed.
>
> Now it all makes sense. Yes, I agree that your patch is the
> appropriate thing to do -- except that it contains at least one logic
> error: It doesn't handle the return code from
> usb_get_device_descriptor() properly.
>
> Also, I think you should expand the immediately preceding comment.
> Explain that it is indeed possible for the port to be enabled at this
> point, because USB-3 connections are initialized automatically by the
> host controller hardware when the connection is detected.
>
> Alan Stern
>
Hi,
I adjusted the patch. Any comments? If it's okay, I will re-sent the patch
to the mailing list.
Here is the second version:
>From dc78b8add72168215b8295e01ce3e2599b4998f7 Mon Sep 17 00:00:00 2001
From: David Heinzelmann <heinzelmann.david@xxxxxxxxx>
Date: Mon, 30 Sep 2019 07:11:31 +0200
Subject: [PATCH v2] Check for changed device descriptors when a connection-change
occurs before validating the connection.
When a port connection-change occurs the hub driver tries to resuscitate an existing
device. Activated from a firmware download a usb device can re-enumerate with new or
changed device descriptors. Therefore it will be checked for changed device descriptors
before the connection is resuscitated and the connection-change event is ignored.
Signed-off-by: David Heinzelmann <heinzelmann.david@xxxxxxxxx>
---
drivers/usb/core/hub.c | 196 +++++++++++++++++++++++------------------
1 file changed, 111 insertions(+), 85 deletions(-)
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 236313f41f4a..45d8bdc9eaae 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -4930,6 +4930,91 @@ hub_power_remaining(struct usb_hub *hub)
return remaining;
}
+
+static int descriptors_changed(struct usb_device *udev,
+ struct usb_device_descriptor *old_device_descriptor,
+ struct usb_host_bos *old_bos)
+{
+ int changed = 0;
+ unsigned index;
+ unsigned serial_len = 0;
+ unsigned len;
+ unsigned old_length;
+ int length;
+ char *buf;
+
+ if (memcmp(&udev->descriptor, old_device_descriptor,
+ sizeof(*old_device_descriptor)) != 0)
+ return 1;
+
+ if ((old_bos && !udev->bos) || (!old_bos && udev->bos))
+ return 1;
+ if (udev->bos) {
+ len = le16_to_cpu(udev->bos->desc->wTotalLength);
+ if (len != le16_to_cpu(old_bos->desc->wTotalLength))
+ return 1;
+ if (memcmp(udev->bos->desc, old_bos->desc, len))
+ return 1;
+ }
+
+ /* Since the idVendor, idProduct, and bcdDevice values in the
+ * device descriptor haven't changed, we will assume the
+ * Manufacturer and Product strings haven't changed either.
+ * But the SerialNumber string could be different (e.g., a
+ * different flash card of the same brand).
+ */
+ if (udev->serial)
+ serial_len = strlen(udev->serial) + 1;
+
+ len = serial_len;
+ for (index = 0; index < udev->descriptor.bNumConfigurations; index++) {
+ old_length = le16_to_cpu(udev->config[index].desc.wTotalLength);
+ len = max(len, old_length);
+ }
+
+ buf = kmalloc(len, GFP_NOIO);
+ if (!buf)
+ /* assume the worst */
+ return 1;
+
+ for (index = 0; index < udev->descriptor.bNumConfigurations; index++) {
+ old_length = le16_to_cpu(udev->config[index].desc.wTotalLength);
+ length = usb_get_descriptor(udev, USB_DT_CONFIG, index, buf,
+ old_length);
+ if (length != old_length) {
+ dev_dbg(&udev->dev, "config index %d, error %d\n",
+ index, length);
+ changed = 1;
+ break;
+ }
+ if (memcmp(buf, udev->rawdescriptors[index], old_length)
+ != 0) {
+ dev_dbg(&udev->dev, "config index %d changed (#%d)\n",
+ index,
+ ((struct usb_config_descriptor *) buf)->
+ bConfigurationValue);
+ changed = 1;
+ break;
+ }
+ }
+
+ if (!changed && serial_len) {
+ length = usb_string(udev, udev->descriptor.iSerialNumber,
+ buf, serial_len);
+ if (length + 1 != serial_len) {
+ dev_dbg(&udev->dev, "serial string error %d\n",
+ length);
+ changed = 1;
+ } else if (memcmp(buf, udev->serial, length) != 0) {
+ dev_dbg(&udev->dev, "serial string changed\n");
+ changed = 1;
+ }
+ }
+
+ kfree(buf);
+ return changed;
+}
+
static void hub_port_connect(struct usb_hub *hub, int port1, u16 portstatus,
u16 portchange)
{
@@ -5167,7 +5252,9 @@ static void hub_port_connect_change(struct usb_hub *hub, int port1,
{
struct usb_port *port_dev = hub->ports[port1 - 1];
struct usb_device *udev = port_dev->child;
+ struct usb_device_descriptor descriptor;
int status = -ENODEV;
+ int retval;
dev_dbg(&port_dev->dev, "status %04x, change %04x, %s\n", portstatus,
portchange, portspeed(hub, portstatus));
@@ -5188,7 +5275,30 @@ static void hub_port_connect_change(struct usb_hub *hub, int port1,
if ((portstatus & USB_PORT_STAT_CONNECTION) && udev &&
udev->state != USB_STATE_NOTATTACHED) {
if (portstatus & USB_PORT_STAT_ENABLE) {
- status = 0; /* Nothing to do */
+ /* USB-3 connections are initialized
+ * automatically by the host controller
+ * hardware. Therefore check for changed
+ * device descriptors before resuscitating
+ * the device.
+ */
+ descriptor = udev->descriptor;
+ retval = usb_get_device_descriptor(udev,
+ sizeof(udev->descriptor));
+ if (retval < 0) {
+ dev_dbg (&udev->dev, "can't read device "
+ "descriptor %d\n", retval);
+ } else {
+ if (descriptors_changed(udev, &descriptor,
+ udev->bos)) {
+ dev_dbg(&udev->dev, "device descriptor "
+ "has changed\n");
+
+ /* for disconnect() calls */
+ udev->descriptor = descriptor;
+ } else {
+ status = 0; /* Nothing to do */
+ }
+ }
#ifdef CONFIG_PM
} else if (udev->state == USB_STATE_SUSPENDED &&
udev->persist_enabled) {
@@ -5550,90 +5660,6 @@ void usb_hub_cleanup(void)
usb_deregister(&hub_driver);
} /* usb_hub_cleanup() */
-static int descriptors_changed(struct usb_device *udev,
- struct usb_device_descriptor *old_device_descriptor,
- struct usb_host_bos *old_bos)
-{
- int changed = 0;
- unsigned index;
- unsigned serial_len = 0;
- unsigned len;
- unsigned old_length;
- int length;
- char *buf;
-
- if (memcmp(&udev->descriptor, old_device_descriptor,
- sizeof(*old_device_descriptor)) != 0)
- return 1;
-
- if ((old_bos && !udev->bos) || (!old_bos && udev->bos))
- return 1;
- if (udev->bos) {
- len = le16_to_cpu(udev->bos->desc->wTotalLength);
- if (len != le16_to_cpu(old_bos->desc->wTotalLength))
- return 1;
- if (memcmp(udev->bos->desc, old_bos->desc, len))
- return 1;
- }
-
- /* Since the idVendor, idProduct, and bcdDevice values in the
- * device descriptor haven't changed, we will assume the
- * Manufacturer and Product strings haven't changed either.
- * But the SerialNumber string could be different (e.g., a
- * different flash card of the same brand).
- */
- if (udev->serial)
- serial_len = strlen(udev->serial) + 1;
-
- len = serial_len;
- for (index = 0; index < udev->descriptor.bNumConfigurations; index++) {
- old_length = le16_to_cpu(udev->config[index].desc.wTotalLength);
- len = max(len, old_length);
- }
-
- buf = kmalloc(len, GFP_NOIO);
- if (!buf)
- /* assume the worst */
- return 1;
-
- for (index = 0; index < udev->descriptor.bNumConfigurations; index++) {
- old_length = le16_to_cpu(udev->config[index].desc.wTotalLength);
- length = usb_get_descriptor(udev, USB_DT_CONFIG, index, buf,
- old_length);
- if (length != old_length) {
- dev_dbg(&udev->dev, "config index %d, error %d\n",
- index, length);
- changed = 1;
- break;
- }
- if (memcmp(buf, udev->rawdescriptors[index], old_length)
- != 0) {
- dev_dbg(&udev->dev, "config index %d changed (#%d)\n",
- index,
- ((struct usb_config_descriptor *) buf)->
- bConfigurationValue);
- changed = 1;
- break;
- }
- }
-
- if (!changed && serial_len) {
- length = usb_string(udev, udev->descriptor.iSerialNumber,
- buf, serial_len);
- if (length + 1 != serial_len) {
- dev_dbg(&udev->dev, "serial string error %d\n",
- length);
- changed = 1;
- } else if (memcmp(buf, udev->serial, length) != 0) {
- dev_dbg(&udev->dev, "serial string changed\n");
- changed = 1;
- }
- }
-
- kfree(buf);
- return changed;
-}
-
/**
* usb_reset_and_verify_device - perform a USB port reset to reinitialize a device
* @udev: device to reset (not in SUSPENDED or NOTATTACHED state)
--
2.20.1
