tty: serial: 8250: use 32bit variable for rpm_tx_active

The kbuild test robot wrote me:
|  make.cross ARCH=powerpc
|>> ERROR: ".__xchg_called_with_bad_pointer" [drivers/tty/serial/8250/8250.ko] undefined!

The generic implementation of xchg() on arm and x86 works for variables of
size one bye (char). According to the report powerpc does not support
xchg() for one byte sized variables and looking further it seems also to
be the same case for sparc and tile (or for 10 out of 26 architectures
which provide a custom implementation).
For that reason I increase the size of the variable from one to four
bytes to get it work on powerpc (and the others).

Reported-By: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h
index c267412..3df10d5 100644 (file)
--- a/include/linux/serial_8250.h
+++ b/include/linux/serial_8250.h
@@ -84,7 +84,7 @@ struct uart_8250_port {
        unsigned char           mcr_mask;       /* mask of user bits */
        unsigned char           mcr_force;      /* mask of forced bits */
        unsigned char           cur_iotype;     /* Running I/O type */
-       unsigned char           rpm_tx_active;
+       unsigned int            rpm_tx_active;
 
        /*
         * Some bits in registers are cleared on a read, so they must