Re: linux-next: build warning after merge of the landlock tree

Mickaël Salaün
2023-10-03T13:15:44Z

PowerPC-64 follows the LP64 data model and then uses int-l64.h (instead of
int-ll64.h like most architectures) for user space code.

Here is the same code with the (suggested) "%lu" token on x86_86:

samples/landlock/sandboxer.c: In function ‘populate_ruleset_net’:
samples/landlock/sandboxer.c:170:77: error: format ‘%lu’ expects argument of type ‘long unsigned int’, but argument 3 has type ‘__u64’ {aka ‘long long unsigned int’} [-Werror=format=]
170 | "Failed to update the ruleset with port \"%lu\": %s\n",
| ~~^
| |
| long unsigned int
| %llu
171 | net_port.port, strerror(errno));
| ~~~~~~~~~~~~~
| |
| __u64 {aka long long unsigned int}

We would then need to cast __u64 to unsigned long long to avoid this warning,
which may look useless, of even buggy, for people taking a look at this sample.

Anyway, it makes more sense to cast it to __u16 because it is the
expected type for a TCP port. I'm updating the patch with that.
Konstantin, please take this fix for the next series:
https://git.kernel.org/mic/c/fc9de206a61a

On Tue, Oct 03, 2023 at 02:27:37PM +1100, Stephen Rothwell wrote:
> Hi all,
>
> After merging the landlock tree, today's linux-next build (powerpc
> allyesconfig) produced this warning:
>
> samples/landlock/sandboxer.c: In function 'populate_ruleset_net':
> samples/landlock/sandboxer.c:170:78: warning: format '%llu' expects argument of type 'long long unsigned int', but argument 3 has type '__u64' {aka 'long unsigned int'} [-Wformat=]
> 170 | "Failed to update the ruleset with port \"%llu\": %s\n",
> | ~~~^
> | |
> | long long unsigned int
> | %lu
> 171 | net_port.port, strerror(errno));
> | ~~~~~~~~~~~~~
> | |
> | __u64 {aka long unsigned int}
>
> Introduced by commit
>
> 24889e7a2079 ("samples/landlock: Add network demo")
>
> --
> Cheers,
> Stephen Rothwell