We need to make sure that the USB serial driver we found
matches the USB driver whose probe we are currently
executing. Otherwise we will end up with USB serial
devices bound to the correct serila driver but wrong
USB driver.
This is a real problem for the generic USB serial driver
because it matches any device.
Signed-off-by: Bjørn Mork <bjorn@xxxxxxx>
---
Hello,
I am not at all sure this is the correct way to fix this,
but at least it solves my problem. I thought about
explicitly matching the generic driver, but the problem
is really more generic. Hence the more generic solution.
More background: The new serial driver code is acting weird.
First time probing work as expected, resulting in something
like this:
May 29 18:23:05 nemi kernel: [ 4253.037118] sierra 4-4:1.0: Sierra USB modem converter detected
May 29 18:23:10 nemi kernel: [ 4258.036828] sierra 4-4:1.2: Sierra USB modem converter detected
May 29 18:23:15 nemi kernel: [ 4263.036837] sierra 4-4:1.3: Sierra USB modem converter detected
and the expected driver attachments:
bjorn@nemi:~$ ls -l /sys/bus/usb/drivers/sierra/
total 0
lrwxrwxrwx 1 root root 0 May 29 18:23 4-4:1.0 -> ../../../../devices/pci0000:00/0000:00:1d.7/usb4/4-4/4-4:1.0
lrwxrwxrwx 1 root root 0 May 29 18:23 4-4:1.2 -> ../../../../devices/pci0000:00/0000:00:1d.7/usb4/4-4/4-4:1.2
lrwxrwxrwx 1 root root 0 May 29 18:23 4-4:1.3 -> ../../../../devices/pci0000:00/0000:00:1d.7/usb4/4-4/4-4:1.3
--w------- 1 root root 4096 May 29 18:23 bind
lrwxrwxrwx 1 root root 0 May 29 18:23 module -> ../../../../module/usbserial
--w------- 1 root root 4096 May 29 18:23 uevent
--w------- 1 root root 4096 May 29 18:23 unbind
bjorn@nemi:~$ ls -l /sys/bus/usb-serial/drivers/sierra/
total 0
--w------- 1 root root 4096 May 29 18:23 bind
lrwxrwxrwx 1 root root 0 May 29 18:23 module -> ../../../../module/sierra
-rw-r--r-- 1 root root 4096 May 29 18:23 new_id
lrwxrwxrwx 1 root root 0 May 29 18:23 ttyUSB0 -> ../../../../devices/pci0000:00/0000:00:1d.7/usb4/4-4/4-4:1.0/ttyUSB0
lrwxrwxrwx 1 root root 0 May 29 18:23 ttyUSB1 -> ../../../../devices/pci0000:00/0000:00:1d.7/usb4/4-4/4-4:1.2/ttyUSB1
lrwxrwxrwx 1 root root 0 May 29 18:23 ttyUSB2 -> ../../../../devices/pci0000:00/0000:00:1d.7/usb4/4-4/4-4:1.3/ttyUSB2
--w------- 1 root root 4096 May 29 18:23 uevent
--w------- 1 root root 4096 May 29 18:23 unbind
But unplugging and replugging resulted in:
May 29 18:26:15 nemi kernel: [ 4442.559246] usbserial_generic 4-4:1.0: Sierra USB modem converter detected
May 29 18:26:20 nemi kernel: [ 4447.556747] usbserial_generic 4-4:1.2: Sierra USB modem converter detected
May 29 18:26:25 nemi kernel: [ 4452.557288] usbserial_generic 4-4:1.3: Sierra USB modem converter detected
Note the driver prefix here. The USB driver is incorrect, but the
USB serial driver is still the same as above. sysfs shows us the
same problem
bjorn@nemi:~$ ls -l /sys/bus/usb/drivers/sierra/
total 0
--w------- 1 root root 4096 May 29 18:23 bind
lrwxrwxrwx 1 root root 0 May 29 18:23 module -> ../../../../module/usbserial
--w------- 1 root root 4096 May 29 18:23 uevent
--w------- 1 root root 4096 May 29 18:23 unbind
bjorn@nemi:~$ ls -l /sys/bus/usb-serial/drivers/sierra/
total 0
--w------- 1 root root 4096 May 29 18:23 bind
lrwxrwxrwx 1 root root 0 May 29 18:23 module -> ../../../../module/sierra
-rw-r--r-- 1 root root 4096 May 29 18:23 new_id
lrwxrwxrwx 1 root root 0 May 29 18:32 ttyUSB0 -> ../../../../devices/pci0000:00/0000:00:1d.7/usb4/4-4/4-4:1.0/ttyUSB0
lrwxrwxrwx 1 root root 0 May 29 18:32 ttyUSB1 -> ../../../../devices/pci0000:00/0000:00:1d.7/usb4/4-4/4-4:1.2/ttyUSB1
lrwxrwxrwx 1 root root 0 May 29 18:32 ttyUSB2 -> ../../../../devices/pci0000:00/0000:00:1d.7/usb4/4-4/4-4:1.3/ttyUSB2
--w------- 1 root root 4096 May 29 18:23 uevent
--w------- 1 root root 4096 May 29 18:23 unbind
bjorn@nemi:~$ ls -l /sys/bus/usb/drivers/usbserial_generic/
total 0
lrwxrwxrwx 1 root root 0 May 29 18:33 4-4:1.0 -> ../../../../devices/pci0000:00/0000:00:1d.7/usb4/4-4/4-4:1.0
lrwxrwxrwx 1 root root 0 May 29 18:33 4-4:1.2 -> ../../../../devices/pci0000:00/0000:00:1d.7/usb4/4-4/4-4:1.2
lrwxrwxrwx 1 root root 0 May 29 18:33 4-4:1.3 -> ../../../../devices/pci0000:00/0000:00:1d.7/usb4/4-4/4-4:1.3
--w------- 1 root root 4096 May 29 18:33 bind
lrwxrwxrwx 1 root root 0 May 29 18:33 module -> ../../../../module/usbserial
--w------- 1 root root 4096 May 29 18:22 uevent
--w------- 1 root root 4096 May 29 18:33 unbind
bjorn@nemi:~$ ls -l /sys/bus/usb-serial/drivers/generic/
total 0
--w------- 1 root root 4096 May 29 18:33 bind
lrwxrwxrwx 1 root root 0 May 29 18:33 module -> ../../../../module/usbserial
-rw-r--r-- 1 root root 4096 May 29 18:33 new_id
--w------- 1 root root 4096 May 29 18:22 uevent
--w------- 1 root root 4096 May 29 18:33 unbind
So we end up with a mismatch between the USB driver and the
USB serial driver. The reason is simple: The probe function
will succeed if *any* registered serial driver matches, and
will use that serial driver so everything works. But we
don't verify which USB driver the probe actually was called
for. The generic driver matches anything, so it will often
be probed for devices handled by other serial drivers.
drivers/usb/serial/usb-serial.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 6a1b609..43bef89 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -732,6 +732,12 @@ static int usb_serial_probe(struct usb_interface *interface,
return -ENODEV;
}
+ /* prevent "cross-probing" - ensure type matches USB driver */
+ if (type->usb_driver != to_usb_driver(interface->dev.driver)) {
+ mutex_unlock(&table_lock);
+ return -ENODEV;
+ }
+
if (!try_module_get(type->driver.owner)) {
mutex_unlock(&table_lock);
dev_err(&interface->dev, "module get failed, exiting\n");
--
1.7.10
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