parport: ieee1284: use del_timer_sync() in parport_wait_event()

Use del_timer_sync() instead of del_timer() to make sure the timer won't
be running when we return from parport_wait_event(), because this would
crash due to destruction of timer_list.

This is untested and just based on a code review.  Just think about the
following sequence of events:

- add_timer()

- down_interruptible() is interrupted by a signal.

- we enter the timer callback handler on another CPU.

- del_timer(), but the timer callback is still running.

- eturn from parport_wait_even, which destroys the automatic variable
  "timer" while the callback is running on another CPU.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Michael Buesch <mb@bu3sch.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/parport/ieee1284.c b/drivers/parport/ieee1284.c
index ac2a805ac7ea642e6bea96fc14bdcbe7a832b3c0..8901ecf6e037c99ab8d514687f091c6e598ba8dd 100644 (file)
--- a/drivers/parport/ieee1284.c
+++ b/drivers/parport/ieee1284.c
@@ -84,7 +84,7 @@ int parport_wait_event (struct parport *port, signed long timeout)
 
        add_timer (&timer);
        ret = down_interruptible (&port->physport->ieee1284.irq);
-       if (!del_timer (&timer) && !ret)
+       if (!del_timer_sync(&timer) && !ret)
                /* Timed out. */
                ret = 1;