On 06/06/2023 10.30, Dan Carpenter wrote:
Hello Jesper Dangaard Brouer,
The patch b62eba563229: "selftests/bpf: Tests using bpf_check_mtu
BPF-helper" from Feb 9, 2021, leads to the following Smatch static
checker warning:
Thanks for reporting this!
./tools/testing/selftests/bpf/prog_tests/check_mtu.c:192 serial_test_check_mtu()
warn: unsigned 'mtu_lo' is never less than zero.
./tools/testing/selftests/bpf/prog_tests/check_mtu.c
184 void serial_test_check_mtu(void)
185 {
186 __u32 mtu_lo;
^^^^^^^^^^^^
This should have been an 'int', because read_mtu_device_lo() uses minus
as error indication.
I'll send a fix patch shortly.
187
188 if (test__start_subtest("bpf_check_mtu XDP-attach"))
189 test_check_mtu_xdp_attach();
190
191 mtu_lo = read_mtu_device_lo();
--> 192 if (CHECK(mtu_lo < 0, "reading MTU value", "failed (err:%d)", mtu_lo))
^^^^^^^^^^
Unsigned can't be less than zero.
193 return;
194
195 if (test__start_subtest("bpf_check_mtu XDP-run"))
196 test_check_mtu_xdp(mtu_lo, 0);
197
198 if (test__start_subtest("bpf_check_mtu XDP-run ifindex-lookup"))
199 test_check_mtu_xdp(mtu_lo, IFINDEX_LO);
200
201 if (test__start_subtest("bpf_check_mtu TC-run"))
202 test_check_mtu_tc(mtu_lo, 0);
203
204 if (test__start_subtest("bpf_check_mtu TC-run ifindex-lookup"))
205 test_check_mtu_tc(mtu_lo, IFINDEX_LO);
206 }
regards,
dan carpenter
--Jesper
