This patch cleans up the locking login in l2cap_sock_recvmsg by pairing
up each lock_sock call with a release_sock call. The function already
has a "done" label that handles releasing the socket and returning from
the function so the fix is rather simple.
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Acked-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

The bt_sock_wait_state requires the sk lock to be held (through
lock_sock) so document it clearly in the code.
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Acked-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

Convert 0 to false and 1 to true when assigning values to bool
variables. Inspired by commit 3db1cd5c.

The simplified semantic patch that find this problem is as
follows (http://coccinelle.lip6.fr/):

@@
bool b;
@@
(
-b = 0
+b = false
|
-b = 1
+b = true
)
Signed-off-by: NPeter Senna Tschudin <peter.senna@gmail.com>
Acked-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

For those controller that support the HCI_Set_Event_Mask_Page_2 command
we should include it in the init sequence. This patch implements sending
of the command and enables the events in it based on supported features
(currently only CSB is checked).
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Acked-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

This patch adds support for reading the synchronization train parameters
for controllers that support the feature. Since the feature is
detectable through the local features page 2, which is retreived only in
stage 3 of the HCI init sequence, there is no other option than to add a
fourth stage to the init sequence.

For now the patch doesn't yet add storing of the parameters, but it is
nevertheless convenient to have around to see what kind of parameters
various controllers use by default (analyzable e.g. with the btmon user
space tool).
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Acked-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

In the case of blocking sockets we should not proceed with sendmsg() if
the socket has the BT_SK_SUSPEND flag set. So far the code was only
ensuring that POLLOUT doesn't get set for non-blocking sockets using
poll() but there was no code in place to ensure that blocking sockets do
the right thing when writing to them.

This patch adds a new bt_sock_wait_ready helper function to sleep in the
sendmsg call if the BT_SK_SUSPEND flag is set, and wake up as soon as it
is unset. It also updates the L2CAP and RFCOMM sendmsg callbacks to take
advantage of this new helper function.
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Acked-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

When we have an LE link we should not respond to any data on the BR/EDR
L2CAP signaling channel (0x0001) and vice-versa when we have a BR/EDR
link we should not respond to LE L2CAP (CID 0x0005) signaling commands.
This patch fixes this issue by checking for a valid link type and
ignores data if it is wrong.
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Acked-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

When L2CAP packets return a non-zero error and the value is passed
onwards by l2cap_bredr_sig_cmd this will trigger a command reject packet
to be sent. However, the core specification (page 1416 in core 4.0) says
the following: "Command Reject packets should not be sent in response to
an identified Response packet.".

This patch ensures that a command reject packet is not sent for any
identified response packet by ignoring the error return value from the
response handler functions.
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Acked-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

There are several possible reason codes that can be sent in the command
reject L2CAP packet. Before this patch the code has used a hard-coded
single response code ("command not understood"). This patch adds a
helper function to map the return value of an L2CAP handler function to
the correct command reject reason.
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Acked-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

If we receive an L2CAP Disconnect Request for an unknown CID we should
not just silently drop it but reply with a proper Command Reject
response. This patch fixes this by ensuring that the disconnect handler
returns a proper error instead of 0 and will cause the function caller
to send the right response.
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Acked-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

The EFAULT error should only be used for memory address related errors
and ENOENT might be needed for other purposes than invalid CID errors.
This patch fixes the l2cap_config_req, l2cap_connect_create_rsp and
l2cap_create_channel_req handlers to use the unique EBADSLT error to
indicate failed lookups on a given CID.
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Acked-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

When an L2CAP request handler returns non-zero the calling code will
send a command reject response. The l2cap_create_chan_req function will
in some cases send its own response but then still return a -EFAULT
error which would cause two responses to be sent. This patch fixes this
by making the function return 0 after sending its own response.
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Acked-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

When the user channel is set and an user application has full control
over the device, do not bother trying to schedule any queues except
the raw queue.

This is an optimization since with user channel, only the raw queue
is in use.
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>
Acked-by: NJohan Hedberg <johan.hedberg@intel.com>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

There is no need to use GFP_ATOMIC with skb_clone() when the code is
executed in a workqueue.
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>
Acked-by: NJohan Hedberg <johan.hedberg@intel.com>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

When the device has the user channel flag set, it means it is driven by
an user application. In that case do not allow any connections from
L2CAP or SCO sockets.

This is the same situation as when the device has the raw flag set and
it will then return EHOSTUNREACH.
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>
Acked-by: NJohan Hedberg <johan.hedberg@intel.com>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

This patch introcuces a new HCI socket channel that allows user
applications to take control over a specific HCI device. The application
gains exclusive access to this device and forces the kernel to stay away
and not manage it. In case of the management interface it will actually
hide the device.

Such operation is useful for security testing tools that need to operate
underneath the Bluetooth stack and need full control over a device. The
advantage here is that the kernel still provides the service of hardware
abstraction and HCI level access. The use of Bluetooth drivers for
hardware access also means that sniffing tools like btmon or hcidump
are still working and the whole set of transaction can be traced with
existing tools.

With the new channel it is possible to send HCI commands, ACL and SCO
data packets and receive HCI events, ACL and SCO packets from the
device. The format follows the well established H:4 protocol.

The new HCI user channel can only be established when a device has been
through its setup routine and is currently powered down. This is
enforced to not cause any problems with current operations. In addition
only one user channel per HCI device is allowed. It is exclusive access
for one user application. Access to this channel is limited to process
with CAP_NET_RAW capability.

Using this new facility does not require any external library or special
ioctl or socket filters. Just create the socket and bind it. After that
the file descriptor is ready to speak H:4 protocol.

        struct sockaddr_hci addr;
        int fd;

        fd = socket(AF_BLUETOOTH, SOCK_RAW, BTPROTO_HCI);

        memset(&addr, 0, sizeof(addr));
        addr.hci_family = AF_BLUETOOTH;
        addr.hci_dev = 0;
        addr.hci_channel = HCI_CHANNEL_USER;

        bind(fd, (struct sockaddr *) &addr, sizeof(addr));

The example shows on how to create a user channel for hci0 device. Error
handling has been left out of the example. However with the limitations
mentioned above it is advised to handle errors. Binding of the user
cahnnel socket can fail for various reasons. Specifically if the device
is currently activated by BlueZ or if the access permissions are not
present.
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

This patch introduces a new user channel flag that allows to give full
control of a HCI device to a user application. The kernel will stay away
from the device and does not allow any further modifications of the
device states.

The existing raw flag is not used since it has a bit of unclear meaning
due to its legacy. Using a new flag makes the code clearer.

A device with the user channel flag set can still be enumerate using the
legacy API, but it does not longer enumerate using the new management
interface used by BlueZ 5 and beyond. This is intentional to not confuse
users of modern systems.
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

The various legacy ioctls used with HCI sockets are limited to raw
channel only. They are not used on the other channels and also have
no meaning there. So return an error if tried to use them.
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

The HCI sockets for monitor and control do not support any HCI specific
socket options and if tried, an error will be returned. However the
error used is EINVAL and that is not really descriptive. To make it
clear that these sockets are not handling HCI socket options, return
EBADFD instead.
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

Even if this is legacy API, there is no reason to not report a proper
error when trying to reset a HCI device that is down.
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

The hci_dev check is not protected and so move it into the socket lock. In
addition return the HCI channel identifier instead of always 0 channel.
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

The HCI sockets do not have a peer associated with it and so make sure
that getpeername() returns EOPNOTSUPP since this operation is actually
not supported on HCI sockets.
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

The handling of the raw socket filter is rather obscure code and it gets
in the way of future extensions. Instead of inline filtering in the raw
socket packet routine, refactor it into its own function.
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

When initiating a transparent eSCO connection, make use of T2 settings
at first try. T2 is the recommended settings from HFP 1.6 WideBand
Speech. Upon connection failure, try T1 settings.

When CVSD is requested and eSCO is supported, try to establish eSCO
connection using S3 settings. If it fails, fallback in sequence to S2,
S1, D1, D0 settings.

To know which setting should be used, conn->attempt is used. It
indicates the currently ongoing SCO connection attempt and can be used
as the index for the fallback settings table.

These setting and the fallback order are described in Bluetooth HFP 1.6
specification p. 101.
Signed-off-by: NFrédéric Dalleau <frederic.dalleau@linux.intel.com>
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

Synchronous Connection Complete event can return error "Connection
Rejected due to Limited resources (0x10)".
Handling this error is required for SCO connection fallback. This error
happens when the server tried to accept the connection but failed to
negotiate settings.
This error code has been verified experimentally by sending a T2 request
to a T1 only SCO listener.

Client dump follows :

< HCI Command (0x01|0x0028) plen 17 [hci0] 3.696064
        Handle: 12
        Transmit bandwidth: 8000
        Receive bandwidth: 8000
        Max latency: 13
        Setting: 0x0003
        Retransmission effort: Optimize for link quality (0x02)
        Packet type: 0x0380
> HCI Event (0x0f) plen 4 [hci0] 3.697034
      Setup Synchronous Connection (0x01|0x0028) ncmd 1
        Status: Success (0x00)
> HCI Event (0x2c) plen 17 [hci0] 3.736059
        Status: Connection Rejected due to Limited Resources (0x0d)
        Handle: 0
        Address: xx:xx:xx:xx:xx:AB (OUI 70-F3-95)
        Link type: eSCO (0x02)
        Transmission interval: 0x0c
        Retransmission window: 0x06
        RX packet length: 60
        TX packet length: 60
        Air mode: Transparent (0x03)

Server dump follows :

> HCI Event (0x04) plen 10 [hci0] 4.741513
        Address: xx:xx:xx:xx:xx:D9 (OUI 20-68-9D)
        Class: 0x620100
          Major class: Computer (desktop, notebook, PDA, organizers)
          Minor class: Uncategorized, code for device not assigned
          Networking (LAN, Ad hoc)
          Audio (Speaker, Microphone, Headset)
          Telephony (Cordless telephony, Modem, Headset)
        Link type: eSCO (0x02)
< HCI Command (0x01|0x0029) plen 21 [hci0] 4.743269
        Address: xx:xx:xx:xx:xx:D9 (OUI 20-68-9D)
        Transmit bandwidth: 8000
        Receive bandwidth: 8000
        Max latency: 13
        Setting: 0x0003
        Retransmission effort: Optimize for link quality (0x02)
        Packet type: 0x03c1
> HCI Event (0x0f) plen 4 [hci0] 4.745517
      Accept Synchronous Connection (0x01|0x0029) ncmd 1
        Status: Success (0x00)
> HCI Event (0x2c) plen 17 [hci0] 4.749508
        Status: Connection Rejected due to Limited Resources (0x0d)
        Handle: 0
        Address: xx:xx:xx:xx:xx:D9 (OUI 20-68-9D)
        Link type: eSCO (0x02)
        Transmission interval: 0x0c
        Retransmission window: 0x06
        RX packet length: 60
        TX packet length: 60
        Air mode: Transparent (0x03)
Signed-off-by: NFrédéric Dalleau <frederic.dalleau@linux.intel.com>
Acked-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

Older Bluetooth devices may not support Setup Synchronous Connection or
SCO transparent data. This is indicated by the corresponding LMP feature
bits. It is not possible to know if the adapter support these features
before setting BT_VOICE option since the socket is not bound to an
adapter. An adapter can also be added after the socket is created. The
socket can be bound to an address before adapter is plugged in.

Thus, on a such adapters, if user request BT_VOICE_TRANSPARENT, outgoing
connections fail on connect() and returns -EOPNOTSUPP. Incoming
connections do not fail. However, they should only be allowed depending
on what was specified in Write_Voice_Settings command.

EOPNOTSUPP is choosen because connect() system call is failing after
selecting route but before any connection attempt.
Signed-off-by: NFrédéric Dalleau <frederic.dalleau@linux.intel.com>
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Acked-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

In order to establish a transparent SCO connection, the correct settings
must be specified in the Setup Synchronous Connection request. For that,
a setting field is added to ACL connection data to set up the desired
parameters. The patch also removes usage of hdev->voice_setting in CVSD
connection and makes use of T2 parameters for transparent data.
Signed-off-by: NFrédéric Dalleau <frederic.dalleau@linux.intel.com>
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Acked-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

When an incoming eSCO connection is requested, check the selected voice
setting and reply appropriately. Voice setting should have been
negotiated previously.  For example, in case of HFP, the codec is
negotiated using AT commands on the RFCOMM channel. This patch only
changes replies for socket with deferred setup enabled.
Signed-off-by: NFrédéric Dalleau <frederic.dalleau@linux.intel.com>
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Acked-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

This patch extends the current Bluetooth socket options with BT_VOICE.
This is intended to choose voice data type at runtime. It only applies
to SCO sockets. Incoming connections shall be setup during deferred
setup. Outgoing connections shall be setup before connect(). The desired
setting is stored in the SCO socket info. This patch declares needed
members, modifies getsockopt() and setsockopt().
Signed-off-by: NFrédéric Dalleau <frederic.dalleau@linux.intel.com>
Acked-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

From Bluetooth Core v4.0 specification, 7.1.8 Accept Connection Request
Command "When accepting synchronous connection request, the Role
parameter is not used and will be ignored by the BR/EDR Controller."
Signed-off-by: NFrédéric Dalleau <frederic.dalleau@linux.intel.com>
Acked-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

hci_connect is a super function for connecting hci protocols. But the
voice_setting parameter (introduced in subsequent patches) is only
needed by SCO and security requirements are not needed for SCO channels.
Thus, it makes sense to have a separate function for SCO.
Signed-off-by: NFrédéric Dalleau <frederic.dalleau@linux.intel.com>
Acked-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

In rfcomm_tty_cleanup we purge the dlc->tx_queue which may contain
socket buffers referencing the tty_port and thus preventing the tty_port
destruction.
Signed-off-by: NGianluca Anzolin <gianluca@sottospazio.it>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

The tty_port can be released in two cases: when we get a HUP in the
functions rfcomm_tty_hangup() and rfcomm_dev_state_change(). Or when the
user releases the device in rfcomm_release_dev().

In these cases we set the flag RFCOMM_TTY_RELEASED so that no other
function can get a reference to the tty_port.
The use of !test_and_set_bit(RFCOMM_TTY_RELEASED) ensures that the
'initial' tty_port reference is only dropped once.

The rfcomm_dev_del function is removed becase it isn't used anymore.
Signed-off-by: NGianluca Anzolin <gianluca@sottospazio.it>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

Implement .activate, .shutdown and .carrier_raised methods of tty_port
to manage the dlc, moving the code from rfcomm_tty_install() and
rfcomm_tty_cleanup() functions.

At the same time the tty .open()/.close() and .hangup() methods are
changed to use the tty_port helpers that properly call the
aforementioned tty_port methods.
Signed-off-by: NGianluca Anzolin <gianluca@sottospazio.it>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

Move the tty_struct initialization from rfcomm_tty_open() to
rfcomm_tty_install() and do the same for the cleanup moving the code from
rfcomm_tty_close() to rfcomm_tty_cleanup().

Add also extra error handling in rfcomm_tty_install() because, unlike
.open()/.close(), .cleanup() is not called if .install() fails.
Signed-off-by: NGianluca Anzolin <gianluca@sottospazio.it>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

The current code removes the device from the device list in several
places. Do it only in the destructor instead and in the error path of
rfcomm_add_dev() if the device couldn't be initialized.
Signed-off-by: NGianluca Anzolin <gianluca@sottospazio.it>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

In net/bluetooth/rfcomm/tty.c the struct tty_struct is used without
taking references. This may lead to a use-after-free of the rfcomm tty.

Fix this by taking references properly, using the tty_port_* helpers
when possible.

The raw assignments of dev->port.tty in rfcomm_tty_open/close are
addressed in the later commit 'rfcomm: Implement .activate, .shutdown
and .carrier_raised methods'.
Signed-off-by: NGianluca Anzolin <gianluca@sottospazio.it>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

In case of a Low Energy only controller it makes no sense to configure
the full BR/EDR event mask. It will just enable events that can not be
send anyway and there is no guarantee that such a controller will accept
this value.

Use event mask 0x90 0xe8 0x04 0x02 0x00 0x80 0x00 0x20 for LE-only
controllers which enables the following events:

          Disconnection Complete
          Encryption Change
          Read Remote Version Information Complete
          Command Complete
          Command Status
          Hardware Error
          Number of Completed Packets
          Data Buffer Overflow
          Encryption Key Refresh Complete
          LE Meta

This is according to Core Specification, Part E, Section 3.
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

When a socket is in deferred state there does actually exist an
underlying connection even though the connection state is not yet
BT_CONNECTED. In the deferred state it should therefore be allowed to
get socket options that usually depend on a connection, such as
SCO_OPTIONS and SCO_CONNINFO.

This patch fixes the behavior of some user space code that behaves as
follows without it:

$ sudo tools/btiotest -i 00:1B:DC:xx:xx:xx -d -s
accept=2 reject=-1 discon=-1 defer=1 sec=0 update_sec=0 prio=0 voice=0x0000
Listening for SCO connections
bt_io_get(OPT_DEST): getsockopt(SCO_OPTIONS): Transport endpoint is not connected (107)
Accepting connection
Successfully connected to 60:D8:19:xx:xx:xx. handle=43, class=000000

The conditions that the patch updates the if-statements to is taken from
similar code in l2cap_sock.c which correctly handles the deferred state.
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

In certain circumstances, such as an HCI driver using __hci_cmd_sync_ev
with HCI_EV_CMD_COMPLETE as the expected completion event there is the
chance that hci_event_packet will call hci_req_cmd_complete twice (once
for the explicitly looked after event and another time in the actual
handler of cmd_complete).

In the case of __hci_cmd_sync_ev this introduces a race where the first
call wakes up the blocking __hci_cmd_sync_ev and lets it complete.
However, by the time that a second __hci_cmd_sync_ev call is already in
progress the second hci_req_cmd_complete call (from the previous
operation) will wake up the blocking function prematurely and cause it
to fail, as witnessed by the following log:

[  639.232195] hci_rx_work: hci0 Event packet
[  639.232201] hci_req_cmd_complete: opcode 0xfc8e status 0x00
[  639.232205] hci_sent_cmd_data: hci0 opcode 0xfc8e
[  639.232210] hci_req_sync_complete: hci0 result 0x00
[  639.232220] hci_cmd_complete_evt: hci0 opcode 0xfc8e
[  639.232225] hci_req_cmd_complete: opcode 0xfc8e status 0x00
[  639.232228] __hci_cmd_sync_ev: hci0 end: err 0
[  639.232234] __hci_cmd_sync_ev: hci0
[  639.232238] hci_req_add_ev: hci0 opcode 0xfc8e plen 250
[  639.232242] hci_prepare_cmd: skb len 253
[  639.232246] hci_req_run: length 1
[  639.232250] hci_sent_cmd_data: hci0 opcode 0xfc8e
[  639.232255] hci_req_sync_complete: hci0 result 0x00
[  639.232266] hci_cmd_work: hci0 cmd_cnt 1 cmd queued 1
[  639.232271] __hci_cmd_sync_ev: hci0 end: err 0
[  639.232276] Bluetooth: hci0 sending Intel patch command (0xfc8e) failed (-61)
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Acked-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>