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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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8af5014276
With clang compiler:
make -j60 LLVM=1 LLVM_IAS=1 <=== compile kernel
# build selftests/bpf or bpftool
make -j60 -C tools/testing/selftests/bpf LLVM=1 LLVM_IAS=1
make -j60 -C tools/bpf/bpftool LLVM=1 LLVM_IAS=1
the following compilation warning showed up,
net.c:160:37: warning: comparison of integers of different signs: '__u32' (aka 'unsigned int') and 'int' [-Wsign-compare]
for (nh = (struct nlmsghdr *)buf; NLMSG_OK(nh, len);
^~~~~~~~~~~~~~~~~
.../tools/include/uapi/linux/netlink.h:99:24: note: expanded from macro 'NLMSG_OK'
(nlh)->nlmsg_len <= (len))
~~~~~~~~~~~~~~~~ ^ ~~~
In this particular case, "len" is defined as "int" and (nlh)->nlmsg_len is "unsigned int".
The macro NLMSG_OK is defined as below in uapi/linux/netlink.h.
#define NLMSG_OK(nlh,len) ((len) >= (int)sizeof(struct nlmsghdr) && \
(nlh)->nlmsg_len >= sizeof(struct nlmsghdr) && \
(nlh)->nlmsg_len <= (len))
The clang compiler complains the comparision "(nlh)->nlmsg_len <= (len))",
but in bpftool/net.c, it is already ensured that "len > 0" must be true.
So theoretically the compiler could deduce that comparison of
"(nlh)->nlmsg_len" and "len" is okay, but this really depends on compiler
internals. Let us add an explicit type conversion (from "int" to "unsigned int")
for "len" in NLMSG_OK to silence this warning right now.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210413153435.3029635-1-yhs@fb.com
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|---|---|---|
| .. | ||
| bash-completion | ||
| Documentation | ||
| skeleton | ||
| .gitignore | ||
| btf.c | ||
| btf_dumper.c | ||
| cfg.c | ||
| cfg.h | ||
| cgroup.c | ||
| common.c | ||
| feature.c | ||
| gen.c | ||
| iter.c | ||
| jit_disasm.c | ||
| json_writer.c | ||
| json_writer.h | ||
| link.c | ||
| main.c | ||
| main.h | ||
| Makefile | ||
| map.c | ||
| map_perf_ring.c | ||
| net.c | ||
| netlink_dumper.c | ||
| netlink_dumper.h | ||
| perf.c | ||
| pids.c | ||
| prog.c | ||
| struct_ops.c | ||
| tracelog.c | ||
| xlated_dumper.c | ||
| xlated_dumper.h | ||