Re: [PATCH bpf-next v6 11/15] selftests/bpf: test_xsk: Don't exit immediately when workers fail

``` commit f89231e503dc0b97c81f4bb32d28532fb3471acd Author: Bastien Curutchet (eBPF Foundation) bastien.curutchet@bootlin.com

selftests/bpf: test_xsk: Don't exit immediately when workers fail

This commit converts the test program from using exit_with_error() (which immediately terminates) to proper error propagation through return values. This allows the test suite to continue running after failures.

diff --git a/tools/testing/selftests/bpf/test_xsk.c b/tools/testing/selftests/bpf/test_xsk.c index 2c955e109..2c392d5b9 100644 --- a/tools/testing/selftests/bpf/test_xsk.c +++ b/tools/testing/selftests/bpf/test_xsk.c

[ ... ]

@@ -759,7 +761,7 @@ static bool is_metadata_correct(struct pkt *pkt, void *buffer, u64 addr) return true; }

-static bool is_adjust_tail_supported(struct xsk_xdp_progs *skel_rx) +static int is_adjust_tail_supported(struct xsk_xdp_progs *skel_rx, bool *supported) { struct bpf_map *data_map; int adjust_value = 0; @@ -769,19 +771,21 @@ static bool is_adjust_tail_supported(struct xsk_xdp_progs *skel_rx) data_map = bpf_object__find_map_by_name(skel_rx->obj, "xsk_xdp_.bss"); if (!data_map || !bpf_map__is_internal(data_map)) { ksft_print_msg("Error: could not find bss section of XDP program\n");

• exit_with_error(errno);
  

• return -EINVAL;
  

  }

  ret = bpf_map_lookup_elem(bpf_map__fd(data_map), &key, &adjust_value); if (ret) { ksft_print_msg("Error: bpf_map_lookup_elem failed with error %d\n", ret);

• exit_with_error(errno);
  

• return ret;
  

  }

  /* Set the 'adjust_value' variable to -EOPNOTSUPP in the XDP program if the adjust_tail

  • helper is not supported. Skip the adjust_tail test case in this scenario.

  */

• return adjust_value != -EOPNOTSUPP;

• *supported = adjust_value != -EOPNOTSUPP;
• return 0;

}

[ ... ]

@@ -1584,29 +1614,41 @@ void *worker_testapp_validate_rx(void *arg) int err;

if (test->current_step == 1) {

• thread_common_ops(test, ifobject);
  

• err = thread_common_ops(test, ifobject);
  

  } else { xsk_clear_xskmap(ifobject->xskmap); err = xsk_update_xskmap(ifobject->xskmap, ifobject->xsk->xsk, 0);

• if (err) {
  

• if (err)
  ksft_print_msg("Error: Failed to update xskmap, error %s\n",
  	       strerror(-err));
  

• 	exit_with_error(-err);
  

• }
  

  }

  pthread_barrier_wait(&barr);

• /* We leave only now in case of error to avoid getting stuck in the barrier */

• if (err) {

• test->fail = true;
  

• pthread_exit(NULL);
  

• }

• err = receive_pkts(test);

  if (!err && ifobject->validation_func) err = ifobject->validation_func(ifobject);

  if (err) {

• if (test->adjust_tail && !is_adjust_tail_supported(ifobject->xdp_progs))
  

• 	test->adjust_tail_support = false;
  

• else
  

• if (!test->adjust_tail) {
  test->fail = true;
  

• } else {
  

• 	bool supported;
  

• 	if (is_adjust_tail_supported(ifobject->xdp_progs, &supported))
  

• 		test->fail = true;
  

• 	if (!supported)
  

• 		test->adjust_tail_support = false;
  

• 	else
  

• 		test->fail = true;
  

• }
  

  }

Can the 'supported' variable be read uninitialized here? When is_adjust_tail_supported() returns an error (non-zero), it doesn't write to the *supported output parameter. The function returns early from either the data_map check or bpf_map_lookup_elem() failure without setting *supported. Then the code unconditionally checks "if (!supported)" which would read uninitialized stack memory.

The control flow is: is_adjust_tail_supported() returns error -> test->fail = true is set -> execution continues to "if (!supported)" -> reads uninitialized 'supported' variable

Should this be structured with an else clause to only check 'supported' when is_adjust_tail_supported() returns success?

```

--- AI reviewed your patch. Please fix the bug or email reply why it's not a bug. See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md

In-Reply-To-Subject: `selftests/bpf: test_xsk: Don't exit immediately when workers fail` CI run summary: https://github.com/kernel-patches/bpf/actions/runs/18910697393