Hi Peter, On Fri, Jan 23, 2015, Peter Hurley wrote: > 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@xxxxxxxxxxxxxxxxxx> > --- > > v2: minor commit log fixes > * s/woken_wait_function/woken_wake_function/ > * indent 'set TASK_RUNNING' under wait_woken to clarify > wait_woken() performs that operation > > net/bluetooth/l2cap_sock.c | 9 ++++----- > net/bluetooth/rfcomm/sock.c | 9 ++++----- > net/bluetooth/sco.c | 8 +++----- > 3 files changed, 11 insertions(+), 15 deletions(-) Applied to bluetooth-next. Thanks! Johan -- To unsubscribe from this list: send the line "unsubscribe linux-bluetooth" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
