Lieing to user space is wrong. The real reason for a failure
to write should be returned to user space.

Signed-off-by: Oliver Neukum <oneukum@suse.de>0
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Do not decrement resp_count if it's already 0.

We set resp_count to 0 when the device is closed.  The next open and
read will try to clear the WDM_READ flag if there was leftover data
in the read buffer. This fix is necessary to prevent resubmitting
the read URB in a tight loop because resp_count becomes negative.

The bug can easily be triggered from userspace by not reading all
data in the read buffer, and then closing and reopening the chardev.

Fixes: 8dd5cd53 ("usb: cdc-wdm: avoid hanging on zero length reads")
Cc: <stable@vger.kernel.org> # 3.13
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

commit 73e06865 ("USB: cdc-wdm: support back-to-back
USB_CDC_NOTIFY_RESPONSE_AVAILABLE notifications") implemented
queued response handling. This added a new requirement: The read
urb must be resubmitted every time we clear the WDM_READ flag if
the response counter indicates that the device is waiting for a
read.

Fix by factoring out the code handling the WMD_READ clearing and
possible urb submission, calling it everywhere we clear the flag.

Without this fix, the driver ends up in a state where the read urb
is inactive, but the response counter is positive after a zero
length read.  This prevents the read urb from ever being submitted
again and the driver appears to be hanging.

Fixes: 73e06865 ("USB: cdc-wdm: support back-to-back USB_CDC_NOTIFY_RESPONSE_AVAILABLE notifications")
Cc: Greg Suarez <gsuarez@smithmicro.com>
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Cc: stable <stable@vger.kernel.org> # 3.13
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Cc: stable <stable@vger.kernel.org>
Reported-by: NOliver Neukum <oneukum@suse.de>
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Acked-by: NOliver Neukum <oneukum@suse.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The only notification supported by the Device Management class is
Response Available. But this driver is also used as a subdriver of
other CDC classes, allowing notifications like Speed Change and
Network Connection. This results in log messages which are only
confusing to an end user:

 [66255.801874] cdc_mbim 1-3:1.5: unknown notification 42 received: index 5 len 8

These drivers use cdc-wdm as a subdriver to allow access to an
embedded management protocol, and all management is expected to
use this protocol. There is therefore no need to handle any of
these optional CDC notifications. Instead we can let the cdc-wdm
driver recognize them and log a debug level message instead of an
error.
Reported-by: NRob Gardner <robmatic@gmail.com>
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Some MBIM devices send back-to-back USB_CDC_NOTIFY_RESPONSE_AVAILABLE notifications
when sending a message over multiple fragments or when there are unsolicited
messages available.

Count up the number of USB_CDC_NOTIFY_RESPONSE_AVAILABLE notifications received
and decrement the count and submit the urb for the next response each time userspace
completes a read the response.
Signed-off-by: NGreg Suarez <gsuarez@smithmicro.com>
Acked-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Both could want to submit the same URB. Some checks of the flag
intended to prevent that were missing.
Signed-off-by: NOliver Neukum <oneukum@suse.de>
CC: stable@vger.kernel.org
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Userspace applications need to know the maximum supported message
size.

The cdc-wdm driver translates between a character device stream
and a message based protocol.  Each message is transported as a
usb control message with no further encapsulation or syncronization.
Each read or write on the character device should translate to
exactly one usb control message to ensure that message boundaries
are kept intact.  That means that the userspace application must
know the maximum message size supported by the device and driver,
making this size a vital part of the cdc-wdm character device API.

CDC WDM and CDC MBIM functions export the maximum supported
message size through CDC functional descriptors.  The cdc-wdm and
cdc_mbim drivers will parse these descriptors and use the value
chosen by the device.  The only current way for a userspace
application to retrive the value is by duplicating the descriptor
parsing. This is an unnecessary complex task, and application
writers are likely to postpone it, using a fixed value and adding
a "todo" item.

QMI functions have no way to tell the host what message size they
support.  The qmi_wwan driver use a fixed value based on protocol
recommendations and observed device behaviour.  Userspace
applications must know and hard code the same value.  This scheme
will break if we ever encounter a QMI device needing a device
specific message size quirk.  We are currently unable to support
such a device because using a non default size would break the
implicit userspace API.

The message size is currently a hidden attribute of the cdc-wdm
userspace API.  Retrieving it is unnecessarily complex, increasing
the possibility of drivers and applications using different limits.
The resulting errors are hard to debug, and can only be replicated
on identical hardware.

Exporting the maximum message size from the driver simplifies the
task for the userspace application, and creates a unified
information source independent of device and function class. It also
serves to document that the message size is part of the cdc-wdm
userspace API.

This proposed API extension has been presented for the authors of
userspace applications and libraries using the current API: libmbim,
libqmi, uqmi, oFono and ModemManager.  The replies were:

Aleksander Morgado:
 "We do really need max message size for MBIM; and as you say, it may be
  good to have the max message size info also for QMI, so the new ioctl
  seems a good addition. So +1 from my side, for what it's worth."

Dan Williams:
 "Yeah, +1 here.  I'd prefer the sysfs file, but the fact that that
  doesn't work for fd passing pretty much kills it."

No negative replies are so far received.

Cc: Aleksander Morgado <aleksander@lanedo.com>
Cc: Dan Williams <dcbw@redhat.com>
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Acked-by: NOliver Neukum <oliver@neukum.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The buffer for responses must not overflow.
If this would happen, set a flag, drop the data and return
an error after user space has read all remaining data.
Signed-off-by: NOliver Neukum <oliver@neukum.org>
CC: stable@kernel.org
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

A logic error made the wdm_find_device* functions
return a bogus pointer into static data instead of
the intended NULL no matching device was found.

Cc: stable <stable@vger.kernel.org> # v3.4+
Cc: Oliver Neukum <oliver@neukum.org>
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Clear the WDM_READ flag on empty reads to avoid running
forever in an infinite tight loop, causing lockups:

Jul  1 21:58:11 nemi kernel: [ 3658.898647] qmi_wwan 2-1:1.2: Unexpected error -71
Jul  1 21:58:36 nemi kernel: [ 3684.072021] BUG: soft lockup - CPU#0 stuck for 23s! [qmi.pl:12235]
Jul  1 21:58:36 nemi kernel: [ 3684.072212] CPU 0
Jul  1 21:58:36 nemi kernel: [ 3684.072355]
Jul  1 21:58:36 nemi kernel: [ 3684.072367] Pid: 12235, comm: qmi.pl Tainted: P           O 3.5.0-rc2+ #13 LENOVO 2776LEG/2776LEG
Jul  1 21:58:36 nemi kernel: [ 3684.072383] RIP: 0010:[<ffffffffa0635008>]  [<ffffffffa0635008>] spin_unlock_irq+0x8/0xc [cdc_wdm]
Jul  1 21:58:36 nemi kernel: [ 3684.072388] RSP: 0018:ffff88022dca1e70  EFLAGS: 00000282
Jul  1 21:58:36 nemi kernel: [ 3684.072393] RAX: ffff88022fc3f650 RBX: ffffffff811c56f7 RCX: 00000001000ce8c1
Jul  1 21:58:36 nemi kernel: [ 3684.072398] RDX: 0000000000000010 RSI: 000000000267d810 RDI: ffff88022fc3f650
Jul  1 21:58:36 nemi kernel: [ 3684.072403] RBP: ffff88022dca1eb0 R08: ffffffffa063578e R09: 0000000000000000
Jul  1 21:58:36 nemi kernel: [ 3684.072407] R10: 0000000000000008 R11: 0000000000000246 R12: 0000000000000002
Jul  1 21:58:36 nemi kernel: [ 3684.072412] R13: 0000000000000246 R14: ffffffff00000002 R15: ffff8802281d8c88
Jul  1 21:58:36 nemi kernel: [ 3684.072418] FS:  00007f666a260700(0000) GS:ffff88023bc00000(0000) knlGS:0000000000000000
Jul  1 21:58:36 nemi kernel: [ 3684.072423] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Jul  1 21:58:36 nemi kernel: [ 3684.072428] CR2: 000000000270d9d8 CR3: 000000022e865000 CR4: 00000000000007f0
Jul  1 21:58:36 nemi kernel: [ 3684.072433] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
Jul  1 21:58:36 nemi kernel: [ 3684.072438] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Jul  1 21:58:36 nemi kernel: [ 3684.072444] Process qmi.pl (pid: 12235, threadinfo ffff88022dca0000, task ffff88022ff76380)
Jul  1 21:58:36 nemi kernel: [ 3684.072448] Stack:
Jul  1 21:58:36 nemi kernel: [ 3684.072458]  ffffffffa063592e 0000000100020000 ffff88022fc3f650 ffff88022fc3f6a8
Jul  1 21:58:36 nemi kernel: [ 3684.072466]  0000000000000200 0000000100000000 000000000267d810 0000000000000000
Jul  1 21:58:36 nemi kernel: [ 3684.072475]  0000000000000000 ffff880212cfb6d0 0000000000000200 ffff880212cfb6c0
Jul  1 21:58:36 nemi kernel: [ 3684.072479] Call Trace:
Jul  1 21:58:36 nemi kernel: [ 3684.072489]  [<ffffffffa063592e>] ? wdm_read+0x1a0/0x263 [cdc_wdm]
Jul  1 21:58:36 nemi kernel: [ 3684.072500]  [<ffffffff8110adb7>] ? vfs_read+0xa1/0xfb
Jul  1 21:58:36 nemi kernel: [ 3684.072509]  [<ffffffff81040589>] ? alarm_setitimer+0x35/0x64
Jul  1 21:58:36 nemi kernel: [ 3684.072517]  [<ffffffff8110aec7>] ? sys_read+0x45/0x6e
Jul  1 21:58:36 nemi kernel: [ 3684.072525]  [<ffffffff813725f9>] ? system_call_fastpath+0x16/0x1b
Jul  1 21:58:36 nemi kernel: [ 3684.072557] Code: <66> 66 90 c3 83 ff ed 89 f8 74 16 7f 06 83 ff a1 75 0a c3 83 ff f4

The WDM_READ flag is normally cleared by wdm_int_callback
before resubmitting the read urb, and set by wdm_in_callback
when this urb returns with data or an error.  But a crashing
device may cause both a read error and cancelling all urbs.
Make sure that the flag is cleared by wdm_read if the buffer
is empty.

We don't clear the flag on errors, as there may be pending
data in the buffer which should be processed.  The flag will
instead be cleared on the next wdm_read call.

Cc: stable <stable@vger.kernel.org>
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Acked-by: NOliver Neukum <oneukum@suse.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

qmi_wwan has been changed to drive both the control and data
interface for all QMI/wwan devices, using cdc-wdm as a subdriver.
Remove the stale device ID entries from cdc-wdm.

>From now on new QMI/wwan devices will only need to be added to
the qmi_wwan driver, regardless of the USB descriptor layout

Note that this is not appropriate for stable/longterm kernels
despite being a device ID patch.

Cc: Oliver Neukum <oliver@neukum.org>
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Tested-by: NThomas Schäfer <tschaefer@t-online.de>
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Hub-initiated LPM is not good for USB communications devices.  Comms
devices should be able to tell when their link can go into a lower power
state, because they know when an incoming transmission is finished.
Ideally, these devices would slam their links into a lower power state,
using the device-initiated LPM, after finishing the last packet of their
data transfer.

If we enable the idle timeouts for the parent hubs to enable
hub-initiated LPM, we will get a lot of useless LPM packets on the bus
as the devices reject LPM transitions when they're in the middle of
receiving data.  Worse, some devices might blindly accept the
hub-initiated LPM and power down their radios while they're in the
middle of receiving a transmission.

The Intel Windows folks are disabling hub-initiated LPM for all USB
communications devices under a xHCI USB 3.0 host.  In order to keep
the Linux behavior as close as possible to Windows, we need to do the
same in Linux.

Set the disable_hub_initiated_lpm flag for for all USB communications
drivers.  I know there aren't currently any USB 3.0 devices that
implement these class specifications, but we should be ready if they do.
Signed-off-by: NSarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: Marcel Holtmann <marcel@holtmann.org>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: Johan Hedberg <johan.hedberg@gmail.com>
Cc: Hansjoerg Lipp <hjlipp@web.de>
Cc: Tilman Schmidt <tilman@imap.cc>
Cc: Karsten Keil <isdn@linux-pingi.de>
Cc: Peter Korsgaard <jacmet@sunsite.dk>
Cc: Jan Dumon <j.dumon@option.com>
Cc: Petko Manolov <petkan@users.sourceforge.net>
Cc: Steve Glendinning <steve.glendinning@smsc.com>
Cc: "John W. Linville" <linville@tuxdriver.com>
Cc: Kalle Valo <kvalo@qca.qualcomm.com>
Cc: "Luis R. Rodriguez" <mcgrof@qca.qualcomm.com>
Cc: Jouni Malinen <jouni@qca.qualcomm.com>
Cc: Vasanthakumar Thiagarajan <vthiagar@qca.qualcomm.com>
Cc: Senthil Balasubramanian <senthilb@qca.qualcomm.com>
Cc: Christian Lamparter <chunkeey@googlemail.com>
Cc: Brett Rudley <brudley@broadcom.com>
Cc: Roland Vossen <rvossen@broadcom.com>
Cc: Arend van Spriel <arend@broadcom.com>
Cc: "Franky (Zhenhui) Lin" <frankyl@broadcom.com>
Cc: Kan Yan <kanyan@broadcom.com>
Cc: Dan Williams <dcbw@redhat.com>
Cc: Jussi Kivilinna <jussi.kivilinna@mbnet.fi>
Cc: Ivo van Doorn <IvDoorn@gmail.com>
Cc: Gertjan van Wingerde <gwingerde@gmail.com>
Cc: Helmut Schaa <helmut.schaa@googlemail.com>
Cc: Herton Ronaldo Krzesinski <herton@canonical.com>
Cc: Hin-Tak Leung <htl10@users.sourceforge.net>
Cc: Larry Finger <Larry.Finger@lwfinger.net>
Cc: Chaoming Li <chaoming_li@realsil.com.cn>
Cc: Daniel Drake <dsd@gentoo.org>
Cc: Ulrich Kunitz <kune@deine-taler.de>
Signed-off-by: NSarah Sharp <sarah.a.sharp@linux.intel.com>

Prevents dereferencing an invalid struct usb_interface
pointer.

Always delete entry from device list whether or not the
rest of the device state cleanup is postponed. The device
list uses desc->intf as key, and wdm_open will dereference
this key while searching for a matching device.  A device
should not appear in the list unless probe() has succeeded
and disconnect() has not finished.

Cc: Oliver Neukum <oliver@neukum.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

We cannot dereference a removed USB interface for
dev_printk. Use pr_debug instead where necessary.

Flush errors are expected if device is unplugged and are
therefore best ingored at this point.

Move the kill_urbs() call in wdm_release with dev_dbg()
for the non disconnect, as we know it has already been
called if WDM_DISCONNECTING is set.  This does not
actually fix anything, but keeps the code more consistent.

Cc: Oliver Neukum <oliver@neukum.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Else the poll will be restarted indefinitely in a tight loop,
preventing final device cleanup.

Cc: Oliver Neukum <oliver@neukum.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

The internal error codes returned in the write() code
path cannot be simply passed on to user space.
Signed-off-by: NOliver Neukum <oneukum@suse.de>
Tested-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Device state cleanup is done in either wdm_disconnect or
wdm_release depending on the order they are called. Adding
a couple of debug messages to document the program flow.
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Acked-by: NOliver Neukum <oneukum@suse.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

cleanup() is not called if the last close() comes after
disconnect(). That leads to a memory leak. Rectified
by checking for an earlier disconnect() in release()
Signed-off-by: NOliver Neukum <oneukum@suse.de>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

wdm_flush() returns unsanitized USB error codes.
They must be cleaned up to before being anded to user space
Signed-off-by: NOliver Neukum <oneukum@suse.de>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This patch fixes a race whereby a pointer to a buffer
would be overwritten while the buffer was in use leading
to a double free and a memory leak. This causes crashes.
This bug was introduced in 2.6.34
Signed-off-by: NOliver Neukum <oneukum@suse.de>
Tested-by: NBjørn Mork <bjorn@mork.no>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This driver can be used as a subdriver of another USB driver, allowing
it to export a Device Managment interface consisting of a single interrupt
endpoint with no dedicated USB interface.

Some devices provide a Device Management function combined with a wwan
function in a single USB interface having three endpoints (bulk in/out
+ interrupt).  If the interrupt endpoint is used exclusively for DM
notifications, then this driver can support that as a subdriver
provided that the wwan driver calls the appropriate entry points on
probe, suspend, resume, pre_reset, post_reset and disconnect.

The main driver must have full control over all interface related
settings, including the needs_remote_wakeup flag. A manage_power
function must be provided by the main driver.

A manage_power stub doing direct flag manipulation is used in normal
driver mode.
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Acked-by: NOliver Neukum <oneukum@suse.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Register all interfaces handled by this driver in a list, getting
rid of the dependency on usb_set_intfdata.  This allows further
generalization and simplification of the probe/create functions.

This is needed to decouple wdm_open from the driver owning the
interface, and it also allows us to share all the code in
wdm_create with drivers unable to do usb_set_intfdata.
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Acked-by: NOliver Neukum <oneukum@suse.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Preparing for the addition of subdriver registering as an alternative
to probe for interface-less usage.  This should not change anything
apart from minor code reordering.
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Acked-by: NOliver Neukum <oneukum@suse.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The WDM_READ flag is cleared later iff desc->length is reduced to 0.
Signed-off-by: NBen Hutchings <ben@decadent.org.uk>
Tested-by: NBjørn Mork <bjorn@mork.no>
Cc: Oliver Neukum <oliver@neukum.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

We must not allow the input buffer length to change while we're
shuffling the buffer contents.  We also mustn't clear the WDM_READ
flag after more data might have arrived.  Therefore move both of these
into the spinlocked region at the bottom of wdm_read().

When reading desc->length without holding the iuspin lock, use
ACCESS_ONCE() to ensure the compiler doesn't re-read it with
inconsistent results.
Signed-off-by: NBen Hutchings <ben@decadent.org.uk>
Tested-by: NBjørn Mork <bjorn@mork.no>
Cc: Oliver Neukum <oliver@neukum.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Add a flag to tell wdm_read/wdm_write that a reset is in progress,
and wake any blocking read/write before taking the mutexes.  This
allows the device to reset without waiting for blocking IO to
finish.
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Acked-by: NOliver Neukum <oneukum@suse.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

[v2: Editorial changes suggested by Sergei Shtylyov]

These modems use the Qualcomm MSM Interface (QMI) protocol for
management of their CDC ECM like wwan interface.  This driver
is perfect for exporting the protocol to userspace.

The created character device will be indistinguishable from a
common AT command based Device Management interface, so
userspace applications must do some intelligent matching
on the USB device.

Cc: Sergei Shtylyov <sshtylyov@mvista.com>
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Acked-by: NOliver Neukum <oneukum@suse.de>
Acked-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

usb_register_dev() will change our .minor_base to 0 if
CONFIG_USB_DYNAMIC_MINORS is set.  And it usually is, of
course.

Use dev_name() to print the proper interface name instead
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Acked-by: NOliver Neukum <oneukum@suse.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

The probe does not strictly require the USB_CDC_DMM_TYPE
descriptor, which is a good thing as it makes the driver
usable on non-conforming interfaces.  A user could e.g.
bind to it to a CDC ECM interface by using the new_id and
bind sysfs files.  But this would fail with a 0 buffer length
due to the missing descriptor.

Fix by defining a reasonable fallback size: The minimum
device receive buffer size required by the CDC WMC standard,
revision 1.1
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

The probe does not strictly require the USB_CDC_DMM_TYPE
descriptor, which is a good thing as it makes the driver
usable on non-conforming interfaces.  A user could e.g.
bind to it to a CDC ECM interface by using the new_id and
bind sysfs files.  But this would fail with a 0 buffer length
due to the missing descriptor.

Fix by defining a reasonable fallback size: The minimum
device receive buffer size required by the CDC WMC standard,
revision 1.1
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

We don't need bMaxPacketSize0, and keeping all these different size fields
around will only cause us to use the wrong one.

Seems the udev variable was only used for getting bMaxPacketSize0.  We
could have used it for the usb_fill_*_urb() calls, but as it wasn't
before - why start now?  Instead make the interface_to_usbdev()
calls consistent.
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

As Documentation/usb/dma.txt states:

  Most drivers should *NOT* be using these primitives; they don't need
  to use this type of memory (dma-coherent), and memory returned from
  kmalloc() will work just fine.

This driver handle only very low bandwith transfers.  It is not an
obvious candidate for usb_alloc_coherent().

Using these calls only serves to complicate the code for no gain,
as has been shown by multiple bugs related to this allocation path.
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

As it turns out, there was a mismatch between the allocated inbuf size
(desc->bMaxPacketSize0, typically something like 64) and the length we
specified in the URB (desc->wMaxCommand, typically something like 2048)
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Cc: Oliver Neukum <oliver@neukum.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Filling the same URB with the exact same data is pointless.  It can be filled
once and resubmitted.  And not doing buffer allocation and URB filling at the
same place only serves to hide size mismatch bugs
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

As it turns out, there was a mismatch between the allocated inbuf size
(desc->bMaxPacketSize0, typically something like 64) and the length we
specified in the URB (desc->wMaxCommand, typically something like 2048)
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Cc: Oliver Neukum <oliver@neukum.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

wdm_disconnect() waits for the mutex held by wdm_read() before
calling wake_up_all().  This causes a deadlock, preventing device removal
to complete.  Do the wake_up_all() before we start waiting for the locks.
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Cc: Oliver Neukum <oliver@neukum.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

using a separate read and write mutex for locking is sufficient to make the
driver accept simultaneous read and write. This improves useability a lot.
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Cc: stable <stable@vger.kernel.org>
Cc: Oliver Neukum <oneukum@suse.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

wdm_in_callback() will also touch this field, so we cannot change it without locking

Cc: stable@vger.kernel.org
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Acked-by: NOliver Neukum <oneukum@suse.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>