serial: core: replace current->state by __set_current_state()

Use helper functions to access current->state.
Direct assignments are prone to races and therefore buggy.

Thanks to Peter Zijlstra for the exact definition of the problem.

Suggested-By: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 6a1055ae343727e964cbb6af44909b42cd526afb..63d29473c703ddfeedce7b24137fe234981f01ff 100644 (file)
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -1118,8 +1118,7 @@ uart_wait_modem_status(struct uart_state *state, unsigned long arg)
 
                cprev = cnow;
        }
-
-       current->state = TASK_RUNNING;
+       __set_current_state(TASK_RUNNING);
        remove_wait_queue(&port->delta_msr_wait, &wait);
 
        return ret;