selftests/bpf: Add test for open coded dmabuf_iter

Use the same test buffers as the traditional iterator and a new BPF map
to verify the test buffers can be found with the open coded dmabuf
iterator.

Signed-off-by: T.J. Mercier <tjmercier@google.com>
Acked-by: Christian König <christian.koenig@amd.com>
Acked-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20250522230429.941193-6-tjmercier@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/testing/selftests/bpf/bpf_experimental.h b/tools/testing/selftests/bpf/bpf_experimental.h
index 6535c8a..5e512a1 100644 (file)
--- a/tools/testing/selftests/bpf/bpf_experimental.h
+++ b/tools/testing/selftests/bpf/bpf_experimental.h
@@ -591,4 +591,9 @@ extern int bpf_iter_kmem_cache_new(struct bpf_iter_kmem_cache *it) __weak __ksym
 extern struct kmem_cache *bpf_iter_kmem_cache_next(struct bpf_iter_kmem_cache *it) __weak __ksym;
 extern void bpf_iter_kmem_cache_destroy(struct bpf_iter_kmem_cache *it) __weak __ksym;
 
+struct bpf_iter_dmabuf;
+extern int bpf_iter_dmabuf_new(struct bpf_iter_dmabuf *it) __weak __ksym;
+extern struct dma_buf *bpf_iter_dmabuf_next(struct bpf_iter_dmabuf *it) __weak __ksym;
+extern void bpf_iter_dmabuf_destroy(struct bpf_iter_dmabuf *it) __weak __ksym;
+
 #endif

diff --git a/tools/testing/selftests/bpf/prog_tests/dmabuf_iter.c b/tools/testing/selftests/bpf/prog_tests/dmabuf_iter.c
index dc740bd..6c2b0c3 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/dmabuf_iter.c
+++ b/tools/testing/selftests/bpf/prog_tests/dmabuf_iter.c
@@ -219,14 +219,52 @@ close_iter_fd:
        close(iter_fd);
 }
 
+static void subtest_dmabuf_iter_check_open_coded(struct dmabuf_iter *skel, int map_fd)
+{
+       LIBBPF_OPTS(bpf_test_run_opts, topts);
+       char key[DMA_BUF_NAME_LEN];
+       int err, fd;
+       bool found;
+
+       /* No need to attach it, just run it directly */
+       fd = bpf_program__fd(skel->progs.iter_dmabuf_for_each);
+
+       err = bpf_prog_test_run_opts(fd, &topts);
+       if (!ASSERT_OK(err, "test_run_opts err"))
+               return;
+       if (!ASSERT_OK(topts.retval, "test_run_opts retval"))
+               return;
+
+       if (!ASSERT_OK(bpf_map_get_next_key(map_fd, NULL, key), "get next key"))
+               return;
+
+       do {
+               ASSERT_OK(bpf_map_lookup_elem(map_fd, key, &found), "lookup");
+               ASSERT_TRUE(found, "found test buffer");
+       } while (bpf_map_get_next_key(map_fd, key, key));
+}
+
 void test_dmabuf_iter(void)
 {
        struct dmabuf_iter *skel = NULL;
+       int map_fd;
+       const bool f = false;
 
        skel = dmabuf_iter__open_and_load();
        if (!ASSERT_OK_PTR(skel, "dmabuf_iter__open_and_load"))
                return;
 
+       map_fd = bpf_map__fd(skel->maps.testbuf_hash);
+       if (!ASSERT_OK_FD(map_fd, "map_fd"))
+               goto destroy_skel;
+
+       if (!ASSERT_OK(bpf_map_update_elem(map_fd, udmabuf_test_buffer_name, &f, BPF_ANY),
+                      "insert udmabuf"))
+               goto destroy_skel;
+       if (!ASSERT_OK(bpf_map_update_elem(map_fd, sysheap_test_buffer_name, &f, BPF_ANY),
+                      "insert sysheap buffer"))
+               goto destroy_skel;
+
        if (!ASSERT_OK(create_test_buffers(), "create_test_buffers"))
                goto destroy;
 
@@ -237,8 +275,11 @@ void test_dmabuf_iter(void)
                subtest_dmabuf_iter_check_no_infinite_reads(skel);
        if (test__start_subtest("default_iter"))
                subtest_dmabuf_iter_check_default_iter(skel);
+       if (test__start_subtest("open_coded"))
+               subtest_dmabuf_iter_check_open_coded(skel, map_fd);
 
 destroy:
        destroy_test_buffers();
+destroy_skel:
        dmabuf_iter__destroy(skel);
 }

diff --git a/tools/testing/selftests/bpf/progs/dmabuf_iter.c b/tools/testing/selftests/bpf/progs/dmabuf_iter.c
index e53d764..13cdb11 100644 (file)
--- a/tools/testing/selftests/bpf/progs/dmabuf_iter.c
+++ b/tools/testing/selftests/bpf/progs/dmabuf_iter.c
@@ -9,6 +9,13 @@
 
 char _license[] SEC("license") = "GPL";
 
+struct {
+       __uint(type, BPF_MAP_TYPE_HASH);
+       __uint(key_size, DMA_BUF_NAME_LEN);
+       __type(value, bool);
+       __uint(max_entries, 5);
+} testbuf_hash SEC(".maps");
+
 /*
  * Fields output by this iterator are delimited by newlines. Convert any
  * newlines in user-provided printed strings to spaces.
@@ -51,3 +58,44 @@ int dmabuf_collector(struct bpf_iter__dmabuf *ctx)
        BPF_SEQ_PRINTF(seq, "%lu\n%llu\n%s\n%s\n", inode, size, name, exporter);
        return 0;
 }
+
+SEC("syscall")
+int iter_dmabuf_for_each(const void *ctx)
+{
+       struct dma_buf *d;
+
+       bpf_for_each(dmabuf, d) {
+               char name[DMA_BUF_NAME_LEN];
+               const char *pname;
+               bool *found;
+               long len;
+               int i;
+
+               if (bpf_core_read(&pname, sizeof(pname), &d->name))
+                       return 1;
+
+               /* Buffers are not required to be named */
+               if (!pname)
+                       continue;
+
+               len = bpf_probe_read_kernel_str(name, sizeof(name), pname);
+               if (len < 0)
+                       return 1;
+
+               /*
+                * The entire name buffer is used as a map key.
+                * Zeroize any uninitialized trailing bytes after the NUL.
+                */
+               bpf_for(i, len, DMA_BUF_NAME_LEN)
+                       name[i] = 0;
+
+               found = bpf_map_lookup_elem(&testbuf_hash, name);
+               if (found) {
+                       bool t = true;
+
+                       bpf_map_update_elem(&testbuf_hash, name, &t, BPF_EXIST);
+               }
+       }
+
+       return 0;
+}