linux/net/bluetooth/rfcomm
Peter Hurley dfb2fae7cd Bluetooth: Fix nested sleeps
l2cap/rfcomm/sco_sock_accept() are wait loops which may acquire
sleeping locks. Since both wait loops and sleeping locks use
task_struct.state to sleep and wake, the nested sleeping locks
destroy the wait loop state.

Use the newly-minted wait_woken() and DEFINE_WAIT_FUNC() for the
wait loop. DEFINE_WAIT_FUNC() allows an alternate wake function
to be specified; in this case, the predefined scheduler function,
woken_wake_function(). This wait construct ensures wakeups will
not be missed without requiring the wait loop to set the
task state before condition evaluation. How this works:

 CPU 0                            |  CPU 1
                                  |
                                  | is <condition> set?
                                  | no
set <condition>                   |
                                  |
wake_up_interruptible             |
  woken_wake_function             |
    set WQ_FLAG_WOKEN             |
    try_to_wake_up                |
                                  | wait_woken
                                  |   set TASK_INTERRUPTIBLE
                                  |   WQ_FLAG_WOKEN? yes
                                  |   set TASK_RUNNING
                                  |
                                  | - loop -
				  |
				  | is <condition> set?
                                  | yes - exit wait loop

Fixes "do not call blocking ops when !TASK_RUNNING" warnings
in l2cap_sock_accept(), rfcomm_sock_accept() and sco_sock_accept().

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
2015-01-23 20:29:42 +02:00
..
core.c Bluetooth: Remove duplicate constant for RFCOMM PSM 2014-12-20 19:55:04 +02:00
Kconfig Bluetooth: Introduce BT_BREDR and BT_LE config options 2014-11-02 10:01:53 +02:00
Makefile [Bluetooth] Move CRC table into RFCOMM core 2005-10-28 19:20:36 +02:00
sock.c Bluetooth: Fix nested sleeps 2015-01-23 20:29:42 +02:00
tty.c Bluetooth: Convert RFCOMM spinlocks into mutexes 2014-05-05 19:25:06 -07:00