On Thu, Mar 07, 2019 at 11:31:55AM +0100, Arnd Bergmann wrote: > Clang points out undefined behavior when building the pcan_usb_pro driver: > > drivers/net/can/usb/peak_usb/pcan_usb_pro.c:136:15: error: passing an object that undergoes default argument promotion to 'va_start' has undefined behavior [-Werror,-Wvarargs] > > Changing the function prototype to avoid argument promotion in the > varargs call avoids the warning, and should make this well-defined. > > Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx> Link: https://github.com/ClangBuiltLinux/linux/issues/109 Reviewed-by: Nathan Chancellor <natechancellor@xxxxxxxxx> I wonder if the format specifier in the pr_err statement at the end of this function should be updated. > --- > drivers/net/can/usb/peak_usb/pcan_usb_pro.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/net/can/usb/peak_usb/pcan_usb_pro.c b/drivers/net/can/usb/peak_usb/pcan_usb_pro.c > index d516def846ab..b388406ac0f5 100644 > --- a/drivers/net/can/usb/peak_usb/pcan_usb_pro.c > +++ b/drivers/net/can/usb/peak_usb/pcan_usb_pro.c > @@ -127,7 +127,7 @@ static u8 *pcan_msg_init_empty(struct pcan_usb_pro_msg *pm, > /* > * add one record to a message being built > */ > -static int pcan_msg_add_rec(struct pcan_usb_pro_msg *pm, u8 id, ...) > +static int pcan_msg_add_rec(struct pcan_usb_pro_msg *pm, int id, ...) > { > int len, i; > u8 *pc; > -- > 2.20.0 >
