[PATCH 00/24] rfcomm fixes

Peter Hurley
2014-02-10T02:20:54Z

Marcel,

This patch series addresses a number of previously unknown issues
with the RFCOMM tty device implementation, in addition to
addressing the locking regression recently reported [1].

As Gianluca suggested and I agree, this series first reverts
3 of the 4 patches of 3.14-rc1 for bluetooth/rfcomm/tty.c.

The reasoning is detailed in the changelog for
Revert "Bluetooth: Always wait for a connection on RFCOMM open()"
but the short answer is that it re-implements a long-standing
bug by blocking on a non-blocking open.

This patch series corrects the reported regressions from 3.13
(to the extent that correction is required). Specifically,
the ModemManager regression reported by Gianluca Anzolin [2]
and the rfcomm bind with wvdial reported by Andrey Vihrov [3].

tty: Fix ref counting for port krefs
Bluetooth: Fix racy acquire of rfcomm_dev reference
Bluetooth: Exclude released devices from RFCOMMGETDEVLIST ioctl
Bluetooth: Release rfcomm_dev only once
Bluetooth: Fix unreleased rfcomm_dev reference
These first 5 patches after the reverts
fix 4 different rfcomm_dev ref count mishandling bugs.

Bluetooth: Fix RFCOMM tty teardown race and
Bluetooth: Serialize RFCOMMCREATEDEV and RFCOMMRELEASEDEV ioctls
Fix races which occur due to the design of the rfcomm ioctls
(note that buses don't have these kinds of races).

Bluetooth: Verify dlci not in use before rfcomm_dev create
Bluetooth: Simplify RFCOMM session state eval
Bluetooth: Refactor deferred setup test in rfcomm_dlc_close()
Bluetooth: Refactor dlc disconnect logic in rfcomm_dlc_close()
Bluetooth: Directly close dlc for not yet started RFCOMM session
These 5 patches fix issues with reusing the dlci after
closing the tty (found by unit test).

Bluetooth: Fix unsafe RFCOMM device parenting
Bluetooth: Fix RFCOMM parent device for reused dlc
These 2 patches fix the ModemManager regression.

Bluetooth: Refactor rfcomm_dev_add()
Bluetooth: Cleanup RFCOMM device registration error handling
These 2 patches fix an unreleased module reference while
error handling.

Bluetooth: Rename __rfcomm_dev_get() to __rfcomm_dev_lookup()
This is a trivial naming patch with no functional impact.

Bluetooth: Force -EIO from tty read/write if .activate() fails
The tty core provides an existing mechanism for failing
reads/writes if device activation fails (like an error
allocating the dlc).

Bluetooth: Don't fail RFCOMM tty writes
This patch implements buffered writes even if the device
is not connected.

While unit testing this, I discovered a serious defect in
the way available space is computed that under-utilizes
rfcomm i/o and may even halt further tx on that link, which
is fixed by:
Bluetooth: Refactor write_room() calculation
Bluetooth: Fix write_room() calculation

Note that this series does not fix the naively inefficient
method of packetizing tty output; packetizing should be
done on the krfcommd thread to take advantage of aggregating
multiple tty writes into 1 or more packets. Look at any
line-by-line console output to realize how under-utilized
the rfcomm tty packeting is.

[1] http://www.spinics.net/lists/linux-wireless/msg117818.html
[2] http://www.spinics.net/lists/linux-bluetooth/msg42075.html
[3] http://www.spinics.net/lists/linux-bluetooth/msg42057.html

Regards,

Peter Hurley (24):
Revert "Bluetooth: Remove rfcomm_carrier_raised()"
Revert "Bluetooth: Always wait for a connection on RFCOMM open()"
Revert "Bluetooth: Move rfcomm_get_device() before
rfcomm_dev_activate()"
tty: Fix ref counting for port krefs
Bluetooth: Fix racy acquire of rfcomm_dev reference
Bluetooth: Exclude released devices from RFCOMMGETDEVLIST ioctl
Bluetooth: Release rfcomm_dev only once
Bluetooth: Fix unreleased rfcomm_dev reference
Bluetooth: Fix RFCOMM tty teardown race
Bluetooth: Verify dlci not in use before rfcomm_dev create
Bluetooth: Simplify RFCOMM session state eval
Bluetooth: Refactor deferred setup test in rfcomm_dlc_close()
Bluetooth: Refactor dlc disconnect logic in rfcomm_dlc_close()
Bluetooth: Directly close dlc for not yet started RFCOMM session
Bluetooth: Fix unsafe RFCOMM device parenting
Bluetooth: Fix RFCOMM parent device for reused dlc
Bluetooth: Rename __rfcomm_dev_get() to __rfcomm_dev_lookup()
Bluetooth: Serialize RFCOMMCREATEDEV and RFCOMMRELEASEDEV ioctls
Bluetooth: Refactor rfcomm_dev_add()
Bluetooth: Cleanup RFCOMM device registration error handling
Bluetooth: Force -EIO from tty read/write if .activate() fails
Bluetooth: Don't fail RFCOMM tty writes
Bluetooth: Refactor write_room() calculation
Bluetooth: Fix write_room() calculation

include/linux/tty.h | 6 +-
include/net/bluetooth/rfcomm.h | 9 +-
net/bluetooth/rfcomm/core.c | 88 ++++++++++----
net/bluetooth/rfcomm/tty.c | 262 ++++++++++++++++++++++-------------------
4 files changed, 223 insertions(+), 142 deletions(-)

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1.8.1.2