The usb_serial_port structure had the number field, which was the minor
number for the port, which almost no one really cared about.  They
really wanted the number of the port within the device, which you had to
subtract from the minor of the parent usb_serial_device structure.  To
clean this up, provide the real minor number of the port, and the number
of the port within the serial device separately, as these numbers might
not be related in the future.

Bonus is that this cleans up a lot of logic in the drivers, and saves
lines overall.
Tested-by: NTobias Winter <tobias@linuxdingsda.de>
Reviewed-by: NJohan Hovold <jhovold@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

--
 drivers/staging/serqt_usb2/serqt_usb2.c |   21 +++--------
 drivers/usb/serial/ark3116.c            |    2 -
 drivers/usb/serial/bus.c                |    6 +--
 drivers/usb/serial/console.c            |    2 -
 drivers/usb/serial/cp210x.c             |    2 -
 drivers/usb/serial/cypress_m8.c         |    4 +-
 drivers/usb/serial/digi_acceleport.c    |    6 ---
 drivers/usb/serial/f81232.c             |    5 +-
 drivers/usb/serial/garmin_gps.c         |    6 +--
 drivers/usb/serial/io_edgeport.c        |   58 ++++++++++++--------------------
 drivers/usb/serial/io_ti.c              |   21 ++++-------
 drivers/usb/serial/keyspan.c            |   29 +++++++---------
 drivers/usb/serial/metro-usb.c          |    4 +-
 drivers/usb/serial/mos7720.c            |   37 +++++++++-----------
 drivers/usb/serial/mos7840.c            |   52 +++++++++-------------------
 drivers/usb/serial/opticon.c            |    2 -
 drivers/usb/serial/pl2303.c             |    2 -
 drivers/usb/serial/quatech2.c           |    7 +--
 drivers/usb/serial/sierra.c             |    2 -
 drivers/usb/serial/ti_usb_3410_5052.c   |   10 ++---
 drivers/usb/serial/usb-serial.c         |    7 ++-
 drivers/usb/serial/usb_wwan.c           |    2 -
 drivers/usb/serial/whiteheat.c          |   20 +++++------
 include/linux/usb/serial.h              |    6 ++-
 24 files changed, 133 insertions(+), 180 deletions(-)

Fix regression introduced by commit 143d9d96 ("USB: serial: add
tiocmiwait subdriver operation") which made the ioctl operation return
ENODEV rather than ENOIOCTLCMD when a subdriver TIOCMIWAIT
implementation is missing.
Signed-off-by: NJohan Hovold <jhovold@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

No need to grab disconnect mutex in chars_in_buffer now that no
sub-driver is or should be querying hardware buffers anymore. (They
should use wait_until_sent.)
Signed-off-by: NJohan Hovold <jhovold@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Add generic wait_until_sent implementation which polls for empty
hardware buffers using the new port-operation tx_empty.

The generic implementation will be used for all sub-drivers that
implement tx_empty but does not define wait_until_sent.
Signed-off-by: NJohan Hovold <jhovold@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Add wait_until_sent operation which can be used to wait for hardware
buffers to drain.
Signed-off-by: NJohan Hovold <jhovold@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This reverts commit eba0e3c3.

When merged together (usb-linus and usb-next), this fix isn't needed and
causes a build error.  Revert the commit to solve the build issue.
Reported-by: NStephen Rothwell <sfr@canb.auug.org.au>
Cc: Ming Lei <tom.leiming@gmail.com>
Cc: Johan Hovold <jhovold@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Johan's 'fix use-after-free in TIOCMIWAIT' patchset[1] introduces
one bug which can cause kernel hang when opening port.

This patch initialized the 'port->delta_msr_wait' waitqueue head
to fix the bug which is introduced in 3.9-rc4.

[1], http://marc.info/?l=linux-usb&m=136368139627876&w=2

Cc: stable <stable@vger.kernel.org>
Signed-off-by: NMing Lei <tom.leiming@gmail.com>
Acked-by: NJohan Hovold <jhovold@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Update copyright information.
Signed-off-by: NJohan Hovold <jhovold@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Make sure processes waiting for modem-status changes are woken up at
disconnect.

This is needed for custom subdriver TIOCMIWAIT-implementations which do
not yet handle hangup.

Even though processes on the tty-port wait queue are woken up at hangup
the wake-up call in usb-serial disconnect is still needed if a woken-up
process may go back to sleep (e.g. due to an incomplete
TIOCMIWAIT-implementation). If a disconnect occurs after a hangup, any
process waiting for changes will not be woken up a second time by the
tty-layer as the port will then have been disassociated from the tty.
Signed-off-by: NJohan Hovold <jhovold@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Add tiocmiwait operation to struct usb_serial_driver.
Signed-off-by: NJohan Hovold <jhovold@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Use usb_poison_urb to reliably kill all urbs on disconnect and suspend.

This way there will be no question that the urbs cannot be resubmitted
by buggy subdrivers.
Signed-off-by: NJohan Hovold <jhovold@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Rename port_release so that all usb_serial_port functions have a common
prefix.
Signed-off-by: NJohan Hovold <jhovold@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

We should not call kill_traffic (and usb_kill_urb) once disconnect
returns. Any pending urbs are killed at disconnect and new submissions
are prevented by usb_unbind_interface (and usb_disable_interface).
Signed-off-by: NJohan Hovold <jhovold@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Most USB serial drivers are, and should be, using as much of the generic
implementation as possible.

Rename the fixup_generic function to a more descriptive name.
Reword the related debug message in a more neutral tone (and remember to
add the missing newline).
Finally, move the operations initialisation to after the initial sanity
checks.
Signed-off-by: NJohan Hovold <jhovold@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Remove empty generic release implementation and make the release
callback non-mandatory (like attach, probe and disconnect).
Signed-off-by: NJohan Hovold <jhovold@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Remove the now empty generic disconnect callback and make the disconnect
callback non-mandatory.
Signed-off-by: NJohan Hovold <jhovold@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Failed allocations already get an OOM message and a stack dump.
Signed-off-by: NJohan Hovold <jhovold@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Remove redundant port number from debug output (already printed as part
of device name).
Signed-off-by: NJohan Hovold <jhovold@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Remove redundant comments and fix some minor coding style issues.
Signed-off-by: NJohan Hovold <jhovold@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Rename the tty-port callbacks using a common prefix to more clearly
separate them from the tty and usb driver callbacks.

Rename serial_down to serial_port_shutdown to match the callback name.
Signed-off-by: NJohan Hovold <jhovold@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

If suspend callback fails in system sleep context, usb core will
ignore the failure and let system sleep go ahead further, so
this patch comments on the case and requires that serial->type->suspend()
MUST return 0 in system sleep context.
Acked-by: NJohan Hovold <jhovold@gmail.com>
Signed-off-by: NMing Lei <ming.lei@canonical.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Make sure the interface is not released before our serial device.

Note that drivers are still not allowed to access the interface in
any way that may interfere with another driver that may have gotten
bound to the same interface after disconnect returns.

Cc: stable <stable@vger.kernel.org>
Signed-off-by: NJohan Hovold <jhovold@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

It allows for cleaning up on a considerable amount of places. They did
port_get, wakeup, kref_put. Now the only thing needed is to call
tty_port_tty_wakeup which does exactly that.

One exception is ifx6x60 where tty_wakeup was open-coded. We now call
tty_wakeup properly there.
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The tty port ops shutdown() routine is not called for console ports;
remove extra check.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Acked-by: NJohan Hovold <jhovold@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Make sure serial-driver dtr_rts is called with disc_mutex held after
checking the disconnected flag.

Due to a bug in the tty layer, dtr_rts may get called after a device has
been disconnected and the tty-device unregistered. Some drivers have had
individual checks for disconnect to make sure the disconnected interface
was not accessed, but this should really be handled in usb-serial core
(at least until the long-standing tty-bug has been fixed).

Note that the problem has been made more acute with commit 0998d063
("device-core: Ensure drvdata = NULL when no driver is bound") as the
port data is now also NULL when dtr_rts is called resulting in further
oopses.
Reported-by: NChris Ruehl <chris.ruehl@gtsys.com.hk>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NJohan Hovold <jhovold@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Grab disconnect mutex in chars_in_buffer before checking disconnected
flag or calling driver specific function.

This allows subdrivers to query any hardware buffer status without
having to handle the locking themselves.
Signed-off-by: NJohan Hovold <jhovold@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

After commit "TTY: move tty buffers to tty_port", the tty buffers are
not freed in some drivers. This is because tty_port_destructor is not
called whenever a tty_port is freed. This was an assumption I counted
with but was unfortunately untrue. So fix the drivers to fulfil this
assumption.

To be sure, the TTY buffers (and later some stuff) are gone along with
the tty_port, we have to call tty_port_destroy at tear-down places.
This is mostly where the structure containing a tty_port is freed.
This patch does exactly that -- put tty_port_destroy at those places.
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

As reported by Fengguang:

FYI, coccinelle warns about

drivers/usb/serial/usb-serial.c:1415:3-51: code aligned with following code on line 1416

vim +1415 drivers/usb/serial/usb-serial.c

  1412          /* we only set the reset_resume field if the serial_driver has one */
  1413          for (sd = serial_drivers; *sd; ++sd) {
  1414                  if ((*sd)->reset_resume)
> 1415                          udriver->reset_resume = usb_serial_reset_resume;
> 1416                          break;
  1417          }
Reported-by: NFengguang Wu <fengguang.wu@intel.com>
Cc: stable <stable@vger.kernel.org> [3.5]
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This moves to using pr_info() where needed instead of a "raw" printk()
call, making the whole driver more unified.

It also cleans up my email address in the MODULE_AUTHOR field.
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Now that all usb-serial modules are only using dev_dbg()
the debug module parameter does not do anything at all, so
remove it to reduce any confusion if someone were to try
to use it.
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This cleans up the usb-serial module to remove all old usages of dbg()
and "raw" printk() calls for error reporting (there are some info
messages left for now.)
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

These dbg() calls were no more than just a function trace, so remove
them.  If you want to see the functions being called, use the in-kernel
function trace code instead, it's much nicer.
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Now that we don't have tty->termios tied to drivers->tty we can untangle
the logic here. In addition we can push the removal logic out of the
destructor path.

At that point we can think about sorting out tty_port and console and all
the other ugly hangovers.
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This will let us sort out a whole pile of tty related races. The
alternative would be to keep points and refcount the termios objects.
However
1. They are tiny anyway
2. Many devices don't use the stored copies
3. We can remove a pty special case
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

To have tty->port set in ->install.
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The use of kfree(serial) in error cases of usb_serial_probe
was invalid - usb_serial structure allocated in create_serial()
gets reference of usb_device that needs to be put, so we need
to use usb_serial_put() instead of simple kfree().
Signed-off-by: NJan Safrata <jan.nikitenko@gmail.com>
Acked-by: NJohan Hovold <jhovold@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

We need to make sure that the USB serial driver we find
matches the USB driver whose probe we are currently
executing. Otherwise we will end up with USB serial
devices bound to the correct serial driver but wrong
USB driver.

An example of such cross-probing, where the usbserial_generic
USB driver has found the sierra serial driver:

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

sysfs view of 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 for the above is simple: The
USB driver probe will succeed if *any* registered serial
driver matches, and will use that serial driver for all
serial driver functions.

This makes ref counting go wrong. We count the USB driver
as used, but not the USB serial driver.  This may result
in Oops'es as demonstrated by Johan Hovold <jhovold@gmail.com>:

[11811.646396] drivers/usb/serial/usb-serial.c: get_free_serial 1
[11811.646443] drivers/usb/serial/usb-serial.c: get_free_serial - minor base = 0
[11811.646460] drivers/usb/serial/usb-serial.c: usb_serial_probe - registering ttyUSB0
[11811.646766] usb 6-1: pl2303 converter now attached to ttyUSB0
[11812.264197] USB Serial deregistering driver FTDI USB Serial Device
[11812.264865] usbcore: deregistering interface driver ftdi_sio
[11812.282180] USB Serial deregistering driver pl2303
[11812.283141] pl2303 ttyUSB0: pl2303 converter now disconnected from ttyUSB0
[11812.283272] usbcore: deregistering interface driver pl2303
[11812.301056] USB Serial deregistering driver generic
[11812.301186] usbcore: deregistering interface driver usbserial_generic
[11812.301259] drivers/usb/serial/usb-serial.c: usb_serial_disconnect
[11812.301823] BUG: unable to handle kernel paging request at f8e7438c
[11812.301845] IP: [<f8e38445>] usb_serial_disconnect+0xb5/0x100 [usbserial]
[11812.301871] *pde = 357ef067 *pte = 00000000
[11812.301957] Oops: 0000 [#1] PREEMPT SMP
[11812.301983] Modules linked in: usbserial(-) [last unloaded: pl2303]
[11812.302008]
[11812.302019] Pid: 1323, comm: modprobe Tainted: G        W    3.4.0-rc7+ #101 Dell Inc. Vostro 1520/0T816J
[11812.302115] EIP: 0060:[<f8e38445>] EFLAGS: 00010246 CPU: 1
[11812.302130] EIP is at usb_serial_disconnect+0xb5/0x100 [usbserial]
[11812.302141] EAX: f508a180 EBX: f508a180 ECX: 00000000 EDX: f8e74300
[11812.302151] ESI: f5050800 EDI: 00000001 EBP: f5141e78 ESP: f5141e58
[11812.302160]  DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068
[11812.302170] CR0: 8005003b CR2: f8e7438c CR3: 34848000 CR4: 000007d0
[11812.302180] DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000
[11812.302189] DR6: ffff0ff0 DR7: 00000400
[11812.302199] Process modprobe (pid: 1323, ti=f5140000 task=f61e2bc0 task.ti=f5140000)
[11812.302209] Stack:
[11812.302216]  f8e3be0f f8e3b29c f8e3ae00 00000000 f513641c f5136400 f513641c f507a540
[11812.302325]  f5141e98 c133d2c1 00000000 00000000 f509c400 f513641c f507a590 f5136450
[11812.302372]  f5141ea8 c12f0344 f513641c f507a590 f5141ebc c12f0c67 00000000 f507a590
[11812.302419] Call Trace:
[11812.302439]  [<c133d2c1>] usb_unbind_interface+0x51/0x190
[11812.302456]  [<c12f0344>] __device_release_driver+0x64/0xb0
[11812.302469]  [<c12f0c67>] driver_detach+0x97/0xa0
[11812.302483]  [<c12f001c>] bus_remove_driver+0x6c/0xe0
[11812.302500]  [<c145938d>] ? __mutex_unlock_slowpath+0xcd/0x140
[11812.302514]  [<c12f0ff9>] driver_unregister+0x49/0x80
[11812.302528]  [<c1457df6>] ? printk+0x1d/0x1f
[11812.302540]  [<c133c50d>] usb_deregister+0x5d/0xb0
[11812.302557]  [<f8e37c55>] ? usb_serial_deregister+0x45/0x50 [usbserial]
[11812.302575]  [<f8e37c8d>] usb_serial_deregister_drivers+0x2d/0x40 [usbserial]
[11812.302593]  [<f8e3a6e2>] usb_serial_generic_deregister+0x12/0x20 [usbserial]
[11812.302611]  [<f8e3acf0>] usb_serial_exit+0x8/0x32 [usbserial]
[11812.302716]  [<c1080b48>] sys_delete_module+0x158/0x260
[11812.302730]  [<c110594e>] ? mntput+0x1e/0x30
[11812.302746]  [<c145c3c3>] ? sysenter_exit+0xf/0x18
[11812.302746]  [<c107777c>] ? trace_hardirqs_on_caller+0xec/0x170
[11812.302746]  [<c145c390>] sysenter_do_call+0x12/0x36
[11812.302746] Code: 24 02 00 00 e8 dd f3 20 c8 f6 86 74 02 00 00 02 74 b4 8d 86 4c 02 00 00 47 e8 78 55 4b c8 0f b6 43 0e 39 f8 7f a9 8b 53 04 89 d8 <ff> 92 8c 00 00 00 89 d8 e8 0e ff ff ff 8b 45 f0 c7 44 24 04 2f
[11812.302746] EIP: [<f8e38445>] usb_serial_disconnect+0xb5/0x100 [usbserial] SS:ESP 0068:f5141e58
[11812.302746] CR2: 00000000f8e7438c

Fix by only evaluating serial drivers pointing back to the
USB driver we are currently probing.  This still allows two
or more drivers to match the same device, running their
serial driver probes to sort out which one to use.

Cc: stable@vger.kernel.org # 3.0, 3.2, 3.3, 3.4
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Reviewed-by: NFelipe Balbi <balbi@ti.com>
Tested-by: NJohan Hovold <jhovold@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

If the usb-serial driver doesn't have a reset_resume callback, then we
need to tell the USB core that it doesn't, and it needs to rebind the
device.

Thanks to Alan for pointing out my mistake, and providing the fix.
Reported-by: NAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Make some noise during probe to make sure the users
are aware of the intended purpose of this driver.
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The callback is now hooked up for any USB to serial driver that wants
it.  We only register the callback if any of the usb-serial structures
want it, this keeps the USB core happy.

Thanks to Alan Stern for the ideas on how to do this.

Cc: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>