[PATCHv2 bpf 3/3] selftest/bpf: test pinning map with reused map fd

[Hangbin Liu]

This add a test to make sure that we can still pin maps with
reused map fd.

Signed-off-by: Hangbin Liu <liuhang...@gmail.com>
---
 .../selftests/bpf/prog_tests/pinning.c        | 46 ++++++++++++++++++-
 1 file changed, 45 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/pinning.c 
b/tools/testing/selftests/bpf/prog_tests/pinning.c
index 041952524c55..299f99ef92b2 100644
--- a/tools/testing/selftests/bpf/prog_tests/pinning.c
+++ b/tools/testing/selftests/bpf/prog_tests/pinning.c
@@ -37,7 +37,7 @@ void test_pinning(void)
        struct stat statbuf = {};
        struct bpf_object *obj;
        struct bpf_map *map;
-       int err;
+       int err, map_fd;
        DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts,
                .pin_root_path = custpath,
        );
@@ -213,6 +213,50 @@ void test_pinning(void)
        if (CHECK(err, "stat custpinpath", "err %d errno %d\n", err, errno))
                goto out;
 
+       /* remove the custom pin path to re-test it with reuse fd below */
+       err = unlink(custpinpath);
+       if (CHECK(err, "unlink custpinpath", "err %d errno %d\n", err, errno))
+               goto out;
+
+       err = rmdir(custpath);
+       if (CHECK(err, "rmdir custpindir", "err %d errno %d\n", err, errno))
+               goto out;
+
+       bpf_object__close(obj);
+
+       /* test pinning at custom path with reuse fd */
+       obj = bpf_object__open_file(file, NULL);
+       if (CHECK_FAIL(libbpf_get_error(obj))) {
+               obj = NULL;
+               goto out;
+       }
+
+       map_fd = bpf_create_map(BPF_MAP_TYPE_ARRAY, sizeof(__u32),
+                               sizeof(__u64), 1, 0);
+       if (CHECK(map_fd < 0, "create pinmap manually", "fd %d\n", map_fd))
+               goto out;
+
+       map = bpf_object__find_map_by_name(obj, "pinmap");
+       if (CHECK(!map, "find map", "NULL map"))
+               goto out;
+
+       err = bpf_map__reuse_fd(map, map_fd);
+       if (CHECK(err, "reuse pinmap fd", "err %d errno %d\n", err, errno))
+               goto out;
+
+       err = bpf_map__set_pin_path(map, custpinpath);
+       if (CHECK(err, "set pin path", "err %d errno %d\n", err, errno))
+               goto out;
+
+       err = bpf_object__load(obj);
+       if (CHECK(err, "custom load", "err %d errno %d\n", err, errno))
+               goto out;
+
+       /* check that pinmap was pinned at the custom path */
+       err = stat(custpinpath, &statbuf);
+       if (CHECK(err, "stat custpinpath", "err %d errno %d\n", err, errno))
+               goto out;
+
 out:
        unlink(pinpath);
        unlink(nopinpath);
-- 
2.25.4