Messages in this thread | | | Date | Mon, 7 Nov 2022 10:45:34 -0800 | Subject | Re: [PATCH bpf] bpf: Add explicit cast to 'void *' for __BPF_DISPATCHER_UPDATE() | From | Yonghong Song <> |
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On 11/7/22 9:07 AM, Nathan Chancellor wrote: > When building with clang: > > kernel/bpf/dispatcher.c:126:33: error: pointer type mismatch ('void *' and 'unsigned int (*)(const void *, const struct bpf_insn *, bpf_func_t)' (aka 'unsigned int (*)(const void *, const struct bpf_insn *, unsigned int (*)(const void *, const struct bpf_insn *))')) [-Werror,-Wpointer-type-mismatch] > __BPF_DISPATCHER_UPDATE(d, new ?: &bpf_dispatcher_nop_func); > ~~~ ^ ~~~~~~~~~~~~~~~~~~~~~~~~ > ./include/linux/bpf.h:1045:54: note: expanded from macro '__BPF_DISPATCHER_UPDATE' > __static_call_update((_d)->sc_key, (_d)->sc_tramp, (_new)) > ^~~~ > 1 error generated. > > The warning is pointing out that the type of new ('void *') and > &bpf_dispatcher_nop_func are not compatible, which could have side > effects coming out of a conditional operator due to promotion rules. > > Add the explicit cast to 'void *' to make it clear that this is > expected, as __BPF_DISPATCHER_UPDATE() expands to a call to > __static_call_update(), which expects a 'void *' as its final argument. > > Fixes: c86df29d11df ("bpf: Convert BPF_DISPATCHER to use static_call() (not ftrace)") > Link: https://github.com/ClangBuiltLinux/linux/issues/1755 > Reported-by: kernel test robot <lkp@intel.com> > Reported-by: "kernelci.org bot" <bot@kernelci.org> > Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
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