two tasks block on rtems_termios_write()

[Yang Ke]

Hello,
    with unknown reason, two tasks in my system (rtems on PPC8260)
blocks on trying to acquire the semaphore. i dump the call stacks
of these two tasks :

task A:
fputs->
........... ->console_write->rtems_termios_write->rtems_semaphore_obtain
->_Thread_Enable_dispatch->_Thread_Dispatch
task B:
vfprintf-> ......>console_write->rtems_termios_write->rtems_termio_puts
-> rtems_semaphore_obtain->_Thread_Enable_dispatch->_Thread_Dispatch

this problem occurs very occasionally and i was not able to reproduce it
in certain steps. from the callstack, looks like deallock happened
somewhere.
did anybody meet the same problem ? and any clues ?

Thanks in advance
yangke