Re: [PATCH 06/12] s390: ctcm: fix ctcm_new_device error return code

Nathan Chancellor
2019-04-08T22:33:34Z

On Mon, Apr 08, 2019 at 11:26:19PM +0200, Arnd Bergmann wrote:
> clang points out that the return code from this function is
> undefined for one of the error paths:
>
> ../drivers/s390/net/ctcm_main.c:1595:7: warning: variable 'result' is used uninitialized whenever 'if' condition is true
> [-Wsometimes-uninitialized]
> if (priv->channel[direction] == NULL) {
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> ../drivers/s390/net/ctcm_main.c:1638:9: note: uninitialized use occurs here
> return result;
> ^~~~~~
> ../drivers/s390/net/ctcm_main.c:1595:3: note: remove the 'if' if its condition is always false
> if (priv->channel[direction] == NULL) {
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> ../drivers/s390/net/ctcm_main.c:1539:12: note: initialize the variable 'result' to silence this warning
> int result;
> ^
>
> Make it return -ENODEV here, as in the related failure cases.
> gcc has a known bug in underreporting some of these warnings
> when it has already eliminated the assignment of the return code
> based on some earlier optimization step.
>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>

> ---
> drivers/s390/net/ctcm_main.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/s390/net/ctcm_main.c b/drivers/s390/net/ctcm_main.c
> index 7617d21cb296..f63c5c871d3d 100644
> --- a/drivers/s390/net/ctcm_main.c
> +++ b/drivers/s390/net/ctcm_main.c
> @@ -1595,6 +1595,7 @@ static int ctcm_new_device(struct ccwgroup_device *cgdev)
> if (priv->channel[direction] == NULL) {
> if (direction == CTCM_WRITE)
> channel_free(priv->channel[CTCM_READ]);
> + result = -ENODEV;
> goto out_dev;
> }
> priv->channel[direction]->netdev = dev;
> --
> 2.20.0
>