Messages in this thread | | | Date | Wed, 16 Aug 2023 20:38:40 -0700 | Subject | Re: [PATCH bpf-next] bpf: Disable -Wmissing-declarations for globally-linked kfuncs | From | Yonghong Song <> |
| |
On 8/16/23 8:06 AM, David Vernet wrote: > We recently got an lkp warning about missing declarations, as in e.g. > [0]. This warning is largely redundant with -Wmissing-prototypes, which > we already disable for kfuncs that have global linkage and are meant to > be exported in BTF, and called from BPF programs. Let's also disable > -Wmissing-declarations for kfuncs. For what it's worth, I wasn't able to > reproduce the warning even on W <= 3, so I can't actually be 100% sure > this fixes the issue. > > [0]: https://lore.kernel.org/all/202308162115.Hn23vv3n-lkp@intel.com/
Okay, I just got a similar email to [0] which complains bpf_obj_new_impl, ..., bpf_cast_to_kern_ctx missing declarations.
In the email, the used compiler is compiler: gcc-7 (Ubuntu 7.5.0-6ubuntu2) 7.5.0
Unfortunately, I did not have gcc-7 to verify this. Also, what is the minimum gcc version kernel supports? 5.1?
> > Reported-by: kernel test robot <lkp@intel.com> > Closes: https://lore.kernel.org/oe-kbuild-all/202308162115.Hn23vv3n-lkp@intel.com/ > Signed-off-by: David Vernet <void@manifault.com> > --- > Documentation/bpf/kfuncs.rst | 4 +++- > kernel/bpf/bpf_iter.c | 2 ++ > kernel/bpf/cpumask.c | 2 ++ > kernel/bpf/helpers.c | 2 ++ > kernel/bpf/map_iter.c | 2 ++ > kernel/cgroup/rstat.c | 2 ++ > kernel/trace/bpf_trace.c | 2 ++ > net/bpf/test_run.c | 2 ++ > net/core/filter.c | 4 ++++ > net/core/xdp.c | 2 ++ > net/ipv4/fou_bpf.c | 2 ++ > net/netfilter/nf_conntrack_bpf.c | 2 ++ > net/netfilter/nf_nat_bpf.c | 2 ++ > net/xfrm/xfrm_interface_bpf.c | 2 ++ > tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c | 2 ++ > 15 files changed, 33 insertions(+), 1 deletion(-) > > diff --git a/Documentation/bpf/kfuncs.rst b/Documentation/bpf/kfuncs.rst > index 0d2647fb358d..62ce5a7b92b4 100644 > --- a/Documentation/bpf/kfuncs.rst > +++ b/Documentation/bpf/kfuncs.rst > @@ -36,10 +36,12 @@ prototype in a header for the wrapper kfunc. > > An example is given below:: > > - /* Disables missing prototype warnings */ > + /* Disables missing prototypes and declarations warnings */ > __diag_push(); > __diag_ignore_all("-Wmissing-prototypes", > "Global kfuncs as their definitions will be in BTF"); > + __diag_ignore_all("-Wmissing-declarations", > + "Global kfuncs as their definitions will be in BTF"); > > __bpf_kfunc struct task_struct *bpf_find_get_task_by_vpid(pid_t nr) > { > diff --git a/kernel/bpf/bpf_iter.c b/kernel/bpf/bpf_iter.c > index 96856f130cbf..b8def6e4e5e8 100644 > --- a/kernel/bpf/bpf_iter.c > +++ b/kernel/bpf/bpf_iter.c > @@ -785,6 +785,8 @@ struct bpf_iter_num_kern { > __diag_push(); > __diag_ignore_all("-Wmissing-prototypes", > "Global functions as their definitions will be in vmlinux BTF"); > +__diag_ignore_all("-Wmissing-declarations", > + "Global functions as their definitions will be in vmlinux BTF"); > > __bpf_kfunc int bpf_iter_num_new(struct bpf_iter_num *it, int start, int end) > { [...]
| |