On Mon, Oct 30, 2023 at 10:56 PM Yafang Shao <laoar.shao@xxxxxxxxx> wrote:
>
> 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.
>
rstat.c and net/socket.c don't have kfuncs, so those are not relevant
here. But we are missing changes also in kernel/bpf/task_iter.c and
kernel/bpf/cgroup_iter.c
And let's update Documentation/bpf/kfuncs.rst to use your new set of macros?
With the above addressed, please add my ack. Thanks!
Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
> --
> Regards
> Yafang
