diff --git a/drivers/tty/isicom.c b/drivers/tty/isicom.c index 858291ca889c..c03ecaa0af7f 100644 --- a/drivers/tty/isicom.c +++ b/drivers/tty/isicom.c @@ -1055,7 +1055,7 @@ static int isicom_send_break(struct tty_struct *tty, int length) outw(0x8000 | ((port->channel) << (card->shift_count)) | 0x3, base); outw((length & 0xff) << 8 | 0x00, base); - outw((length & 0xff00), base); + outw((length & 0xff00u), base); InterruptTheCard(base); unlock_card(card);
Commit f3e2d56dce47dbd0bb3f69f84741b439542fef37 upstream. Building an arm allmodconfig kernel triggers a lengthy but harmless warning in the isicom driver: drvers/tty/isicom.c: In function 'isicom_send_break': uapi/linux/swab.h:13:15: warning: integer overflow in expression [-Woverflow] (((__u16)(x) & (__u16)0x00ffU) << 8) | \ ^ uapi/linux/swab.h:107:2: note: in expansion of macro '___constant_swab16' ___constant_swab16(x) : \ ^ uapi/linux/byteorder/big_endian.h:34:43: note: in expansion of macro '__swab16' #define __cpu_to_le16(x) ((__force __le16)__swab16((x))) ^ linux/byteorder/generic.h:89:21: note: in expansion of macro '__cpu_to_le16' #define cpu_to_le16 __cpu_to_le16 ^ include/asm/io.h:270:6: note: in expansion of macro 'cpu_to_le16' cpu_to_le16(v),__io(p)); }) ^ drivers/tty/isicom.c:1058:2: note: in expansion of macro 'outw' outw((length & 0xff00), base); ^ Apparently, the problem is related to the fact that the value 0xff00, when used as a 16-bit number, is negative and passed into bitwise operands of the generic byte swapping code. Marking the input argument as unsigned in both technically correct and avoids the warning. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- drivers/tty/isicom.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) -- 2.9.0