Application programs should use a libraw1394 handle only in a single
thread. The raw1394 driver was apparently relying on this, because it
did nothing to protect its fi->state variable from corruption due to
concurrent accesses.
We now serialize the fi->state accesses. This affects the write() path.
We re-use the state_mutex which was introduced to protect fi->iso_state
accesses in the ioctl() path. These paths and accesses are independent
of each other, hence separate mutexes could be used. But I don't see
much benefit in that.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
f22e52b89e