[PATCH] tty: serial: 8250: use 32bit variable for rpm_tx_active

From: Sebastian Andrzej Siewior
Date: Mon Sep 29 2014 - 04:21:14 EST

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@xxxxxxxxx>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
include/linux/serial_8250.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h
index c267412a3ef4..3df10d5f154b 100644
--- 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

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