Re: [PATCH v12 6/7] eal: add unit tests for atomic bit access functions

[David Marchand <david.marchand@redhat.com>]

On Fri, Oct 11, 2024 at 5:06 PM Morten Brørup <mb@smartsharesystems.com> wrote:
>
> > From: David Marchand [mailto:david.marchand@redhat.com]
> > Sent: Thursday, 10 October 2024 12.45
> >
> > On Fri, Sep 20, 2024 at 12:57 PM Mattias Rönnblom
> > <mattias.ronnblom@ericsson.com> wrote:
> > > +       static int
> > \
> > > +       run_parallel_test_and_modify ## size(void *arg)         \
> > > +       {
> > \
> > > +               struct parallel_test_and_set_lcore ## size *lcore =
> > arg; \
> > > +               uint64_t deadline = rte_get_timer_cycles() +
> > \
> > > +                       PARALLEL_TEST_RUNTIME * rte_get_timer_hz();
> > \
> > > +               do {
> > \
> > > +                       bool old_value;
> > \
> > > +                       bool new_value = rte_rand() & 1;
> > \
> > > +                       bool use_assign = rte_rand() & 1;
> > \
> > > +
> > \
> > > +                       if (use_assign)
> > \
> > > +                               old_value =
> > rte_bit_atomic_test_and_assign( \
> > > +                                       lcore->word, lcore->bit,
> > new_value, \
> > > +                                       rte_memory_order_relaxed);
> > \
> > > +                       else
> > \
> > > +                               old_value = new_value ?
> > \
> > > +                                       rte_bit_atomic_test_and_set(
> > \
> > > +                                               lcore->word, lcore-
> > >bit, \
> > > +
> > rte_memory_order_relaxed) : \
> > > +
> > rte_bit_atomic_test_and_clear(  \
> > > +                                               lcore->word, lcore-
> > >bit, \
> > > +
> > rte_memory_order_relaxed); \
> > > +                       if (old_value != new_value)
> > \
> > > +                               lcore->flips++;
> > \
> > > +               } while (rte_get_timer_cycles() < deadline);
> > \
> > > +
> > \
> > > +               return 0;
> > \
> > > +       }
> > \
> > > +
> > \
> > > +       static int
> > \
> > > +       test_bit_atomic_parallel_test_and_modify ## size(void)
> > \
> > > +       {
> > \
> > > +               unsigned int worker_lcore_id;
> > \
> > > +               uint ## size ## _t word = 0;
> > \
> > > +               unsigned int bit = rte_rand_max(size);
> > \
> > > +               struct parallel_test_and_set_lcore ## size lmain = {
> > \
> > > +                       .word = &word,
> > \
> > > +                       .bit = bit
> > \
> > > +               };
> > \
> > > +               struct parallel_test_and_set_lcore ## size lworker =
> > {  \
> > > +                       .word = &word,
> > \
> > > +                       .bit = bit
> > \
> > > +               };
> > \
> > > +
> > \
> > > +               if (rte_lcore_count() < 2) {
> > \
> > > +                       printf("Need multiple cores to run parallel
> > test.\n"); \
> > > +                       return TEST_SKIPPED;
> > \
> > > +               }
> > \
> > > +
> > \
> > > +               worker_lcore_id = rte_get_next_lcore(-1, 1, 0);
> > \
> > > +
> > \
> > > +               int rc =
> > rte_eal_remote_launch(run_parallel_test_and_modify ## size, \
> > > +                                              &lworker,
> > worker_lcore_id); \
> > > +               TEST_ASSERT(rc == 0, "Worker thread launch failed");
> > \
> > > +
> > \
> > > +               run_parallel_test_and_modify ## size(&lmain);
> > \
> > > +
> > \
> > > +               rte_eal_mp_wait_lcore();
> > \
> > > +
> > \
> > > +               uint64_t total_flips = lmain.flips + lworker.flips;
> > \
> > > +               bool expected_value = total_flips % 2;
> > \
> > > +
> > \
> > > +               TEST_ASSERT(expected_value == rte_bit_test(&word,
> > bit), \
> > > +                           "After %"PRId64" flips, the bit value "
> > \
> > > +                           "should be %d", total_flips,
> > expected_value); \
> > > +
> > \
> > > +               uint64_t expected_word = 0;
> > \
> > > +               rte_bit_assign(&expected_word, bit, expected_value);
> > \
> > > +
> > \
> > > +               TEST_ASSERT(expected_word == word, "Untouched bits
> > have " \
> > > +                           "changed value");
> > \
> > > +
> > \
> > > +               return TEST_SUCCESS;
> > \
> > > +       }
> > > +
> > > +GEN_TEST_BIT_PARALLEL_TEST_AND_MODIFY(32)
> > > +GEN_TEST_BIT_PARALLEL_TEST_AND_MODIFY(64)
> >
> > It appears this test failed once in the CI for an unrelated series
> > (uAPI kernel header import):
> > https://lab.dpdk.org/results/dashboard/testruns/logs/1385993/
> >
> >  + TestCase [ 0] : test_bit_access32 succeeded
> >  + TestCase [ 1] : test_bit_access64 succeeded
> >  + TestCase [ 2] : test_bit_access32 succeeded
> >  + TestCase [ 3] : test_bit_access64 succeeded
> >  + TestCase [ 4] : test_bit_v_access32 succeeded
> >  + TestCase [ 5] : test_bit_v_access64 succeeded
> >  + TestCase [ 6] : test_bit_atomic_access32 succeeded
> >  + TestCase [ 7] : test_bit_atomic_access64 succeeded
> >  + TestCase [ 8] : test_bit_atomic_v_access32 succeeded
> >  + TestCase [ 9] : test_bit_atomic_v_access64 succeeded
> >  + TestCase [10] : test_bit_atomic_parallel_assign32 succeeded
> >  + TestCase [11] : test_bit_atomic_parallel_assign64 succeeded
> >  + TestCase [12] : test_bit_atomic_parallel_test_and_modify32 failed
> >  + TestCase [13] : test_bit_atomic_parallel_test_and_modify64 succeeded
> >  + TestCase [14] : test_bit_atomic_parallel_flip32 succeeded
> >  + TestCase [15] : test_bit_atomic_parallel_flip64 succeeded
> >  + TestCase [16] : test_bit_relaxed_set succeeded
> >  + TestCase [17] : test_bit_relaxed_clear succeeded
> >  + TestCase [18] : test_bit_relaxed_test_set_clear succeeded
> >
> > EAL: Test assert test_bit_atomic_parallel_test_and_modify32 line 236
> > failed: After 1070523 flips, the bit value should be 1
> >
> > Please have a look.
>
> The Coverity report [1] just gave me an idea:
>
> worker_lcore_id = rte_get_next_lcore(-1, 1, 0);
> + TEST_ASSERT(worker_lcore_id < RTE_MAX_LCORE, "Worker thread allocation failed");
>
> Or even better:
> Improve rte_eal_remote_launch() by checking the validity of the worker_id parameter.
>
> [1]: https://scan4.scan.coverity.com/#/project-view/60887/10075?selectedIssue=445384
>

I have the same fix in my workdir, I was about to send, but if you
want to do it, go ahead.


-- 
David Marchand