From: Nathan Chancellor nathan@kernel.org
[ Upstream commit a679120edfcf3d63f066f53afd425d51b480e533 ]
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: Björn Töpel bjorn@kernel.org Acked-by: Yonghong Song yhs@fb.com Link: https://lore.kernel.org/r/20221107170711.42409-1-nathan@kernel.org Signed-off-by: Martin KaFai Lau martin.lau@kernel.org Signed-off-by: Vasiliy Kovalev kovalev@altlinux.org --- kernel/bpf/dispatcher.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/bpf/dispatcher.c b/kernel/bpf/dispatcher.c index 23042cfb5e809..9959201efc316 100644 --- a/kernel/bpf/dispatcher.c +++ b/kernel/bpf/dispatcher.c @@ -117,7 +117,7 @@ static void bpf_dispatcher_update(struct bpf_dispatcher *d, int prev_num_progs) return; }
- __BPF_DISPATCHER_UPDATE(d, new ?: &bpf_dispatcher_nop_func); + __BPF_DISPATCHER_UPDATE(d, new ?: (void *)&bpf_dispatcher_nop_func);
if (new) d->image_off = noff;