l2cap_ertm_send() can be called both from user context and bottom half
context. The socket locks for that contexts are different, the user
context uses a mutex(which can sleep) and the second one uses a
spinlock_bh. That creates a race condition when we have interruptions on
both contexts at the same time.
The better way to solve this is to add a new spinlock to lock
l2cap_ertm_send() and the vars it access. The other solution was to defer
l2cap_ertm_send() with a workqueue, but we the sending process already
has one defer on the hci layer. It's not a good idea add another one.
The patch refactor the code to create l2cap_retransmit_frames(), then we
encapulate the lock of l2cap_ertm_send() for some call. It also changes
l2cap_retransmit_frame() to l2cap_retransmit_one_frame() to avoid
confusion
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
Reviewed-by: João Paulo Rechi Vita <jprvita@profusion.mobi>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Supports Local Busy condition handling through a waitqueue that wake ups
each 200ms and try to push the packets to the upper layer. If it can
push all the queue then it leaves the Local Busy state.
The patch modifies the behaviour of l2cap_ertm_reassembly_sdu() to
support retry of the push operation.
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
Reviewed-by: João Paulo Rechi Vita <jprvita@profusion.mobi>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
With the sockopt extension we can set a per-channel MaxTx value.
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
Reviewed-by: João Paulo Rechi Vita <jprvita@profusion.mobi>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Now that we can set the txWindow we need to change the acknowledgement
procedure to ack after each (pi->txWindow/6 + 1). The plus 1 is to avoid
the zero value.
It also renames pi->num_to_ack to a better name: pi->num_acked.
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
Reviewed-by: João Paulo Rechi Vita <jprvita@profusion.mobi>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Now we can set/get Transmission Window size via sockopt.
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
Reviewed-by: João Paulo Rechi Vita <jprvita@profusion.mobi>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
We were accepting values bigger than we can accept. This was leading
ERTM to drop packets because of wrong FCS checks.
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
Reviewed-by: João Paulo Rechi Vita <jprvita@profusion.mobi>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
We ack I-frames on each txWindow/5 I-frames received, but if the sender
stop to send I-frames and it's not a txWindow multiple we can leave some
frames unacked.
So I added a timer to ack I-frames on this case. The timer expires in
200ms.
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
Reviewed-by: João Paulo Rechi Vita <jprvita@profusion.mobi>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
After receive a RR with P bit set ERTM shall use this funcion to choose
what type of frame to reply with F bit = 1.
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
Reviewed-by: João Paulo Rechi Vita <jprvita@profusion.mobi>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
RejActioned is used to prevent retransmission when a entity is on the
WAIT_F state, i.e., waiting for a frame with F-bit set due local busy
condition or a expired retransmission timer. (When these two events raise
they send a frame with the Poll bit set and enters in the WAIT_F state to
wait for a frame with the Final bit set.)
The local entity doesn't send I-frames(the data frames) until the receipt
of a frame with F-bit set. When that happens it also set RejActioned to false.
RejActioned is a mandatory feature of ERTM spec.
Signed-off-by: Gustavo F. Padovan <gustavo@las.ic.unicamp.br>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
As specified by ERTM spec an ERTM channel can acknowledge received
I-frames(the data frames) by sending an I-frame with the proper ReqSeq
value (i.e. ReqSeq is set to BufferSeq). Until now we aren't setting the
ReqSeq value on I-frame control bits. That way we can save sending
S-frames(Supervise frames) only to acknowledge receipt of I-frames. It
is very helpful to the full-duplex channel.
ReqSeq is the packet sequence number sent in an acknowledgement frame to
acknowledge receipt of frames up to (ReqSeq - 1).
BufferSeq controls the receiver buffer, it is used to delay
acknowledgement of new frames to not cause buffer overflow. BufferSeq
value is not increased until frames are pulled by reassembly function.
Signed-off-by: Gustavo F. Padovan <gustavo@las.ic.unicamp.br>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Implement all issues related to RemoteBusy in the RECV state table.
Signed-off-by: Gustavo F. Padovan <gustavo@las.ic.unicamp.br>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Support for receiving of SREJ frames as specified by the state table.
Signed-off-by: Gustavo F. Padovan <gustavo@las.ic.unicamp.br>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
When L2CAP loses an I-frame we send a SREJ frame to the transmitter side
requesting the lost packet. This patch implement all Recv I-frame events
on SREJ_SENT state table except the ones that deal with SendRej (the REJ
exception at receiver side is yet not implemented).
Signed-off-by: Gustavo F. Padovan <gustavo@las.ic.unicamp.br>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Implement CRC16 check for L2CAP packets. FCS is used by Streaming Mode and
Enhanced Retransmission Mode and is a extra check for the packet content.
Using CRC16 is the default, L2CAP won't use FCS only when both side send
a "No FCS" request.
Initially based on a patch from Nathan Holstein <nathan@lampreynetworks.com>
Signed-off-by: Gustavo F. Padovan <gustavo@las.ic.unicamp.br>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
L2CAP uses retransmission and monitor timers to inquiry the other side
about unacked I-frames. After sending each I-frame we (re)start the
retransmission timer. If it expires, we start a monitor timer that send a
S-frame with P bit set and wait for S-frame with F bit set. If monitor
timer expires, try again, at a maximum of L2CAP_DEFAULT_MAX_TX.
Signed-off-by: Gustavo F. Padovan <gustavo@las.ic.unicamp.br>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
When receiving an I-frame with unexpected txSeq, receiver side start the
recovery procedure by sending a REJ S-frame to the transmitter side. So
the transmitter can re-send the lost I-frame.
This patch just adds a basic support for retransmission, it doesn't
mean that ERTM now has full support for packet retransmission.
Signed-off-by: Gustavo F. Padovan <gustavo@las.ic.unicamp.br>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
ERTM should use Segmentation and Reassembly to break down a SDU in many
PDUs on sending data to the other side.
On sending packets we queue all 'segments' until end of segmentation and
just the add them to the queue for sending. On receiving we create a new
SKB with the SDU reassembled.
Initially based on a patch from Nathan Holstein <nathan@lampreynetworks.com>
Signed-off-by: Gustavo F. Padovan <gustavo@las.ic.unicamp.br>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
This patch adds support for ERTM transfers, without retransmission, with
txWindow up to 63 and with acknowledgement of packets received. Now the
packets are queued before call l2cap_do_send(), so packets couldn't be
sent at the time we call l2cap_sock_sendmsg(). They will be sent in
an asynchronous way on later calls of l2cap_ertm_send(). Besides if an
error occurs on calling l2cap_do_send() we disconnect the channel.
Initially based on a patch from Nathan Holstein <nathan@lampreynetworks.com>
Signed-off-by: Gustavo F. Padovan <gustavo@las.ic.unicamp.br>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Add support to config_req and config_rsp to configure ERTM and Streaming
mode. If the remote device specifies ERTM or Streaming mode, then the
same mode is proposed. Otherwise ERTM or Basic mode is used. And in case
of a state 2 device, the remote device should propose the same mode. If
not, then the channel gets disconnected.
Signed-off-by: Gustavo F. Padovan <gustavo@las.ic.unicamp.br>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
To enable Enhanced Retransmission mode it needs to be set via a socket
option. A different mode can be set on a socket, but on listen() and
connect() the mode is checked and ERTM is only allowed if it is enabled
via the module parameter.
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
This adds the basic constants required to add support for L2CAP Enhanced
Retransmission feature.
Based on a patch from Nathan Holstein <nathan@lampreynetworks.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Using the L2CAP_CONF_HINT macro is easier to understand than using a
hardcoded 0x80 value.
Signed-off-by: Gustavo F. Padovan <gustavo@las.ic.unicamp.br>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Use macros instead of hardcoded numbers to make the L2CAP source code
more readable.
Signed-off-by: Gustavo F. Padovan <gustavo@las.ic.unicamp.br>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Some of the qualification tests demand that in case of failures in L2CAP
the HCI disconnect should indicate a reason why L2CAP fails. This is a
bluntly layer violation since multiple L2CAP connections could be using
the same ACL and thus forcing a disconnect reason is not a good idea.
To comply with the Bluetooth test specification, the disconnect reason
is now stored in the L2CAP connection structure and every time a new
L2CAP channel is added it will set back to its default. So only in the
case where the L2CAP channel with the disconnect reason is really the
last one, it will propagated to the HCI layer.
The HCI layer has been extended with a disconnect indication that allows
it to ask upper layers for a disconnect reason. The upper layer must not
support this callback and in that case it will nicely default to the
existing behavior. If an upper layer like L2CAP can provide a disconnect
reason that one will be used to disconnect the ACL or SCO link.
No modification to the ACL disconnect timeout have been made. So in case
of Linux to Linux connection the initiator will disconnect the ACL link
before the acceptor side can signal the specific disconnect reason. That
is perfectly fine since Linux doesn't make use of this value anyway. The
L2CAP layer has a perfect valid error code for rejecting connection due
to a security violation. It is unclear why the Bluetooth specification
insists on having specific HCI disconnect reason.
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
In preparation for L2CAP fixed channel support, the CID value of a
L2CAP connection needs to be accessible via the socket interface. The
CID is the connection identifier and exists as source and destination
value. So extend the L2CAP socket address structure with this field and
change getsockname() and getpeername() to fill it in.
The bind() and connect() functions have been modified to handle L2CAP
socket address structures of variable sizes. This makes them future
proof if additional fields need to be added.
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
If the extended features mask indicates support for fixed channels,
request the list of available fixed channels. This also enables the
fixed channel features bit so remote implementations can request
information about it. Currently only the signal channel will be
listed.
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
If the remote L2CAP server uses authentication pending stage and
encryption is enabled it can happen that a L2CAP connection request is
sent twice due to a race condition in the connection state machine.
When the remote side indicates any kind of connection pending, then
track this state and skip sending of L2CAP commands for this period.
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
When two L2CAP connections are requested quickly after the ACL link has
been established there exists a window for a race condition where a
connection request is sent before the information response has been
received. Any connection request should only be sent after an exchange
of the extended features mask has been finished.
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
In case the remote entity tries to negogiate retransmission or flow
control mode, reject it and fall back to basic mode.
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
The Bluetooth 1.2 specification introduced a specific features mask
value to interoperate with newer versions of the specification. So far
this piece of information was never needed, but future extensions will
rely on it. This patch adds a generic way to retrieve this information
only once per connection setup.
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
After the change to the L2CAP configuration parameter handling the
global conf_mtu variable is no longer needed and so remove it.
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
no code changes, just documenting existing types
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
The L2CAP configuration parameter handling was missing the support
for rejecting unknown options. The capability to reject unknown
options is mandatory since the Bluetooth 1.2 specification. This
patch implements its and also simplifies the parameter parsing.
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
