On Tue, Oct 31, 2023 at 5:07 AM Dave Marchevsky <davemarchevsky@xxxxxx> wrote:
>
> BPF kfuncs are meant to be called from BPF programs. Accordingly, most
> kfuncs are not called from anywhere in the kernel, which the
> -Wmissing-prototypes warning is unhappy about. We've peppered
> __diag_ignore_all("-Wmissing-prototypes", ... everywhere kfuncs are
> defined in the codebase to suppress this warning.
>
> This patch adds two macros meant to bound one or many kfunc definitions.
> All existing kfunc definitions which use these __diag calls to suppress
> -Wmissing-prototypes are migrated to use the newly-introduced macros.
> A new __diag_ignore_all - for "-Wmissing-declarations" - is added to the
> __bpf_kfunc_start_defs macro based on feedback from Andrii on an earlier
> version of this patch [0] and another recent mailing list thread [1].
>
> In the future we might need to ignore different warnings or do other
> kfunc-specific things. This change will make it easier to make such
> modifications for all kfunc defs.
>
> [0]: https://lore.kernel.org/bpf/CAEf4BzaE5dRWtK6RPLnjTW-MW9sx9K3Fn6uwqCTChK2Dcb1Xig@xxxxxxxxxxxxxx/
> [1]: https://lore.kernel.org/bpf/ZT+2qCc%2FaXep0%2FLf@krava/
>
> Signed-off-by: Dave Marchevsky <davemarchevsky@xxxxxx>
> Suggested-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
> Cc: Jiri Olsa <olsajiri@xxxxxxxxx>
> ---
>
> This patch was submitted earlier as part of task_vma
> iter series: https://lore.kernel.org/bpf/20231013204426.1074286-6-davemarchevsky@xxxxxx/
>
> This separate submission addresses Andrii's comments from
> that thread.
>
> include/linux/btf.h | 9 +++++++++
> kernel/bpf/bpf_iter.c | 6 ++----
> kernel/bpf/cpumask.c | 6 ++----
> kernel/bpf/helpers.c | 6 ++----
> kernel/bpf/map_iter.c | 6 ++----
> kernel/bpf/task_iter.c | 6 ++----
> kernel/trace/bpf_trace.c | 6 ++----
> net/bpf/test_run.c | 7 +++----
> net/core/filter.c | 13 ++++---------
> net/core/xdp.c | 6 ++----
> net/ipv4/fou_bpf.c | 6 ++----
> net/netfilter/nf_conntrack_bpf.c | 6 ++----
> net/netfilter/nf_nat_bpf.c | 6 ++----
> net/xfrm/xfrm_interface_bpf.c | 6 ++----
> 14 files changed, 38 insertions(+), 57 deletions(-)
>
Thanks for your work.
By using a simple grep for "__diag_ignore_all(\"-Wmissing-prototypes",
it appears that the files net/socket.c,
tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c,
kernel/cgroup/rstat.c and Documentation/bpf/kfuncs.rst are missing. It
seems that we should also update them.
--
Regards
Yafang
