Re: [PATCH 3/4] selftests/bpf: Add test for dmabuf_iter

On Mon, Apr 14, 2025 at 3:53 PM T.J. Mercier tjmercier@google.com wrote:

This test creates a udmabuf and uses a BPF program that prints dmabuf metadata with the new dmabuf_iter to verify it can be found.

Signed-off-by: T.J. Mercier tjmercier@google.com

[...]

+static void subtest_dmabuf_iter_check_udmabuf(struct dmabuf_iter *skel) +{

•   static const char test_buffer_name[] = "udmabuf_test_buffer_for_iter";
  

•   const size_t test_buffer_size = 10 * getpagesize();
  

•   ASSERT_LE(sizeof(test_buffer_name), DMA_BUF_NAME_LEN, "NAMETOOLONG");
  

•   int memfd = memfd_create("memfd_test", MFD_ALLOW_SEALING);
  

•   ASSERT_OK_FD(memfd, "memfd_create");
  

Please do not mix variable declaration with the rest of the code. Also, please run checkpatch.pl on the patches. I see a few warnings.

•   ASSERT_OK(ftruncate(memfd, test_buffer_size), "ftruncate");
  

•   ASSERT_OK(fcntl(memfd, F_ADD_SEALS, F_SEAL_SHRINK), "seal");
  

•   int dev_udmabuf = open("/dev/udmabuf", O_RDONLY);
  

•   ASSERT_OK_FD(dev_udmabuf, "open udmabuf");
  

[...]

•   ASSERT_TRUE(found_test_udmabuf, "found_test_buffer");
  

•   free(line);
  

•   fclose(iter_file);
  

•   close(iter_fd);
  

•   close(udmabuf);
  

•   close(memfd);
  

+}

+void test_dmabuf_iter(void) +{

•   struct dmabuf_iter *skel = NULL;
  

•   char buf[256];
  

•   int iter_fd;
  

•   skel = dmabuf_iter__open_and_load();
  

•   if (!ASSERT_OK_PTR(skel, "dmabuf_iter__open_and_load"))
  

•           return;
  

•   if (!ASSERT_OK(dmabuf_iter__attach(skel), "skel_attach"))
  

•           goto destroy;
  

•   iter_fd = bpf_iter_create(bpf_link__fd(skel->links.dmabuf_collector));
  

•   if (!ASSERT_GE(iter_fd, 0, "iter_create"))
  

Use ASSERT_OK_FD here?

•           goto destroy;
  

•   memset(buf, 0, sizeof(buf));
  

•   while (read(iter_fd, buf, sizeof(buf) > 0)) {
  

•           /* Read out all contents */
  

•   }
  

[...]