The current ACM runtime-suspend implementation is broken in several
ways:

Firstly, it buffers only the first write request being made while
suspended -- any further writes are silently dropped.

Secondly, writes being dropped also leak write urbs, which are never
reclaimed (until the device is unbound).

Thirdly, even the single buffered write is not cleared at shutdown
(which may happen before the device is resumed), something which can
lead to another urb leak as well as a PM usage-counter leak.

Fix this by implementing a delayed-write queue using urb anchors and
making sure to discard the queue properly at shutdown.

Fixes: 11ea859d ("USB: additional power savings for cdc-acm devices
that support remote wakeup")
Reported-by: Xiao Jin <jin.xiao@intel.com>
Cc: <stable@vger.kernel.org>	# v2.6.27
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Fix race between write() and resume() due to improper locking that could
lead to writes being reordered.

Resume must be done atomically and susp_count be protected by the
write_lock in order to prevent racing with write(). This could otherwise
lead to writes being reordered if write() grabs the write_lock after
susp_count is decremented, but before the delayed urb is submitted.

Fixes: 11ea859d ("USB: additional power savings for cdc-acm devices
that support remote wakeup")

Cc: <stable@vger.kernel.org>	# v2.6.27
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Fix race between write() and suspend() which could lead to writes being
dropped (or I/O while suspended) if the device is runtime suspended
while a write request is being processed.

Specifically, suspend() releases the write_lock after determining the
device is idle but before incrementing the susp_count, thus leaving a
window where a concurrent write() can submit an urb.

Fixes: 11ea859d ("USB: additional power savings for cdc-acm devices
that support remote wakeup")

Cc: <stable@vger.kernel.org>        # v2.6.27
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Fix incorrect pipe directions and remove bogus data buffer arguments
from control requests without data stage.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The only way a port pointer may be NULL is if probe() failed, and in
that case neither disconnect(), resume(), or reset_resume() will be
called.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Only call usb_autopm_put_interface() if the corresponding
usb_autopm_get_interface() was successful.

This prevents a potential runtime PM counter imbalance should
usb_autopm_get_interface() fail. Note that the USB PM usage counter is
reset when the interface is unbound, but that the runtime PM counter may
be left unbalanced.

Also add comment on why we don't need to worry about racing
resume/suspend on autopm_get failures.

Fixes: d5fd650c ("usb: serial: prevent suspend/resume from racing
against probe/remove")
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Use tty-port initialised flag rather than private flag to determine when
port is closing down.

Since the tty-port flag is set prior to dropping DTR/RTS (when HUPCL is
set) this avoid submitting the read urbs when resuming the interface in
dtr_rts() only to immediately kill them again in shutdown().
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Promote failed-submission messages in open() and write() to error log
level.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The usb_wwan_send_setup() function has never existed.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Remove some more outdated or superfluous comments.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Remove superfluous and cryptic comment from close.

It should be obvious that we're balancing the autopm_put in open (and
that operation already mentions the autopm_get done in the USB serial
core).
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Clean up and rename delay-urb submission function using a more
descriptive name.

Also add comment on locking assumptions.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Use usb_get_serial_data() rather than accessing the private pointer
directly.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Make resume error messages uniform.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

As the port interrupt URB is submitted by the subdriver at open, we
should also kill it explicitly at suspend (even though this will be
taken care of by USB serial core otherwise).
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Remove redundant usb_kill_urb from port remove, which is called
post-shutdown (close).
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The driver does not implement set_termios so the operation can be left
unset (tty will do the tty_termios_copy_hw for us).

Note that the send_setup call is bogus as it really only sets DTR/RTS
to their current values.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The tty-port implementation has already made sure that DTR/RTS have been
raised by calling dtr_rts so remove the redundant call from open.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Make sure that needs_remote_wake up is always set when there are open
ports.

Currently close() would unconditionally set needs_remote_wakeup to 0
even though there might still be open ports. This could lead to blocked
input and possibly dropped data on devices that do not support remote
wakeup (and which must therefore not be runtime suspended while open).

Add an open_ports counter (protected by the susp_lock) and only clear
needs_remote_wakeup when the last port is closed.

Note that there are currently no multi-port drivers using the usb_wwan
implementation.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

There's no reason not to try sending off any further delayed write urbs,
should one urb-submission fail.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Keep trying to submit urbs rather than bail out on first read-urb
submission error, which would also prevent I/O for any further ports
from being resumed.

Instead keep an error count, for all types of failed submissions, and
let USB core know that something went wrong.

Also make sure to always clear the suspended flag. Currently a failed
read-urb submission would prevent cached writes as well as any
subsequent writes from being submitted until next suspend-resume cycle,
something which may not even necessarily happen.

Note that USB core currently only logs an error if an interface resume
failed.

Fixes: 383cedc3 ("USB: serial: full autosuspend support for the
option driver")

Cc: <stable@vger.kernel.org>	# v2.6.32
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The interrupt urb was submitted unconditionally at resume, something
which could lead to a NULL-pointer dereference in the urb completion
handler as resume may be called after the port and port data is gone.

Fix this by making sure the interrupt urb is only submitted and active
when the port is open.

Fixes: 383cedc3 ("USB: serial: full autosuspend support for the
option driver")

Cc: <stable@vger.kernel.org>  # v2.6.32: 032129cbSigned-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The delayed-write queue was never emptied at shutdown (close), something
which could lead to leaked urbs if the port is closed before being
runtime resumed due to a write.

When this happens the output buffer would not drain on close
(closing_wait timeout), and after consecutive opens, writes could be
corrupted with previously buffered data, transfered with reduced
throughput or completely blocked.

Note that unbusy_queued_urb() was simply moved out of CONFIG_PM.

Fixes: 383cedc3 ("USB: serial: full autosuspend support for the
option driver")

Cc: <stable@vger.kernel.org>	# v2.6.32
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Fix race between write() and suspend() which could lead to writes being
dropped (or I/O while suspended) if the device is runtime suspended
while a write request is being processed.

Specifically, suspend() releases the susp_lock after determining the
device is idle but before setting the suspended flag, thus leaving a
window where a concurrent write() can submit an urb.

Fixes: 383cedc3 ("USB: serial: full autosuspend support for the
option driver")

Cc: <stable@vger.kernel.org>	# v2.6.32
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

We find a race between write and resume. usb_wwan_resume run play_delayed()
and spin_unlock, but intfdata->suspended still is not set to zero.
At this time usb_wwan_write is called and anchor the urb to delay
list. Then resume keep running but the delayed urb have no chance
to be commit until next resume. If the time of next resume is far
away, tty will be blocked in tty_wait_until_sent during time. The
race also can lead to writes being reordered.

This patch put play_Delayed and intfdata->suspended together in the
spinlock, it's to avoid the write race during resume.

Fixes: 383cedc3 ("USB: serial: full autosuspend support for the
option driver")
Signed-off-by: xiao jin <jin.xiao@intel.com>
Signed-off-by: Zhang, Qi1 <qi1.zhang@intel.com>
Reviewed-by: David Cohen <david.a.cohen@linux.intel.com>
Cc: <stable@vger.kernel.org>	# v2.6.32
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

When enable usb serial for modem data, sometimes the tty is blocked
in tty_wait_until_sent because portdata->out_busy always is set and
have no chance to be cleared.

We find a bug in write error path. usb_wwan_write set portdata->out_busy
firstly, then try autopm async with error. No out urb submit and no
usb_wwan_outdat_callback to this write, portdata->out_busy can't be
cleared.

This patch clear portdata->out_busy if usb_wwan_write try autopm async
with error.

Fixes: 383cedc3 ("USB: serial: full autosuspend support for the
option driver")
Signed-off-by: xiao jin <jin.xiao@intel.com>
Signed-off-by: Zhang, Qi1 <qi1.zhang@intel.com>
Reviewed-by: David Cohen <david.a.cohen@linux.intel.com>
Cc: <stable@vger.kernel.org>	# v2.6.32
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

We should call usb_mark_last_busy in all input paths, including the
interrupt completion handler.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The option line-control request has been using the wrong pipe direction,
while relying on USB core to fix it up.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Fix potential I/O while runtime suspended due to missing PM operations
in send_setup.

Fixes: 383cedc3 ("USB: serial: full autosuspend support for the
option driver")

Cc: <stable@vger.kernel.org>        # v2.6.32
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Use tty-port initialised flag rather than private flag to determine when
port is closing down.

Since the tty-port flag is set prior to dropping DTR/RTS (when HUPCL is
set) this avoid submitting the read urbs when resuming the interface in
dtr_rts() only to immediately kill them again in shutdown().
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Move usb_autopm_get_interface_no_resume to the end of close(). This
makes the window during which suspend is prevented before the final put
in USB serial core slightly smaller.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Refactor and clean up delayed-urb submission at resume.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Clean up suspend() somewhat and make sure to always set the suspended
flag (although it's only used for runtime PM) in order to match
resume().
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Use usb_get_serial_data() rather than accessing the private pointer
directly.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The tty-port implementation has already made sure that DTR/RTS have been
raised and lowered by calling dtr_rts so remove the redundant calls from
open and close.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Do not resume any I/O, including the delayed write queue, on closed
ports.

Note that this currently has no functional impact due to the
usb_autopm_get_interface() in close(), but that call is about to be
removed by a follow-up patch.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Remove no longer needed disconnected test from close, which is never
called post disconnect (and drivers must handle failed I/O during
disconnect anyway).
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The driver does not implement set_termios so the operation can be left
unset (tty will do the tty_termios_copy_hw for us).

Note that the send_setup call is bogus as it really only sets DTR/RTS
to their current values.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Remove unused variable from sierra_release_urb.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Remove bogus endpoint-address test which is never true.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>