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Message-ID: <20190806174028.GB23939@mini-arch>
Date: Tue, 6 Aug 2019 10:40:28 -0700
From: Stanislav Fomichev <sdf@...ichev.me>
To: Andrii Nakryiko <andrii.nakryiko@...il.com>
Cc: Stanislav Fomichev <sdf@...gle.com>,
Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
"David S. Miller" <davem@...emloft.net>,
Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Andrii Nakryiko <andriin@...com>
Subject: Re: [PATCH bpf-next v4 1/3] selftests/bpf: test_progs: switch to
open_memstream
On 08/06, Andrii Nakryiko wrote:
> On Tue, Aug 6, 2019 at 10:19 AM Stanislav Fomichev <sdf@...gle.com> wrote:
> >
> > Use open_memstream to override stdout during test execution.
> > The copy of the original stdout is held in env.stdout and used
> > to print subtest info and dump failed log.
> >
> > test_{v,}printf are now simple wrappers around stdout and will be
> > removed in the next patch.
> >
> > v4:
> > * one field per line for stdout/stderr (Andrii Nakryiko)
> >
> > v3:
> > * don't do strlen over log_buf, log_cnt has it already (Andrii Nakryiko)
> >
> > v2:
> > * add ifdef __GLIBC__ around open_memstream (maybe pointless since
> > we already depend on glibc for argp_parse)
> > * hijack stderr as well (Andrii Nakryiko)
> > * don't hijack for every test, do it once (Andrii Nakryiko)
> > * log_cap -> log_size (Andrii Nakryiko)
> > * do fseeko in a proper place (Andrii Nakryiko)
> > * check open_memstream returned value (Andrii Nakryiko)
> >
> > Cc: Andrii Nakryiko <andriin@...com>
> > Acked-by: Andrii Nakryiko <andriin@...com>
> > Signed-off-by: Stanislav Fomichev <sdf@...gle.com>
> > ---
> > tools/testing/selftests/bpf/test_progs.c | 115 ++++++++++++-----------
> > tools/testing/selftests/bpf/test_progs.h | 3 +-
> > 2 files changed, 62 insertions(+), 56 deletions(-)
> >
> > diff --git a/tools/testing/selftests/bpf/test_progs.c b/tools/testing/selftests/bpf/test_progs.c
> > index db00196c8315..9556439c607c 100644
> > --- a/tools/testing/selftests/bpf/test_progs.c
> > +++ b/tools/testing/selftests/bpf/test_progs.c
> > @@ -40,14 +40,20 @@ static bool should_run(struct test_selector *sel, int num, const char *name)
> >
> > static void dump_test_log(const struct prog_test_def *test, bool failed)
> > {
> > + if (stdout == env.stdout)
> > + return;
> > +
> > + fflush(stdout); /* exports env.log_buf & env.log_cnt */
> > +
> > if (env.verbose || test->force_log || failed) {
> > if (env.log_cnt) {
> > - fprintf(stdout, "%s", env.log_buf);
> > + fprintf(env.stdout, "%s", env.log_buf);
> > if (env.log_buf[env.log_cnt - 1] != '\n')
> > - fprintf(stdout, "\n");
> > + fprintf(env.stdout, "\n");
> > }
> > }
> > - env.log_cnt = 0;
> > +
> > + fseeko(stdout, 0, SEEK_SET); /* rewind */
> > }
> >
> > void test__end_subtest()
> > @@ -62,7 +68,7 @@ void test__end_subtest()
> >
> > dump_test_log(test, sub_error_cnt);
> >
> > - printf("#%d/%d %s:%s\n",
> > + fprintf(env.stdout, "#%d/%d %s:%s\n",
> > test->test_num, test->subtest_num,
> > test->subtest_name, sub_error_cnt ? "FAIL" : "OK");
> > }
> > @@ -79,7 +85,8 @@ bool test__start_subtest(const char *name)
> > test->subtest_num++;
> >
> > if (!name || !name[0]) {
> > - fprintf(stderr, "Subtest #%d didn't provide sub-test name!\n",
> > + fprintf(env.stderr,
> > + "Subtest #%d didn't provide sub-test name!\n",
> > test->subtest_num);
> > return false;
> > }
> > @@ -100,53 +107,7 @@ void test__force_log() {
> >
> > void test__vprintf(const char *fmt, va_list args)
> > {
> > - size_t rem_sz;
> > - int ret = 0;
> > -
> > - if (env.verbose || (env.test && env.test->force_log)) {
> > - vfprintf(stderr, fmt, args);
> > - return;
> > - }
> > -
> > -try_again:
> > - rem_sz = env.log_cap - env.log_cnt;
> > - if (rem_sz) {
> > - va_list ap;
> > -
> > - va_copy(ap, args);
> > - /* we reserved extra byte for \0 at the end */
> > - ret = vsnprintf(env.log_buf + env.log_cnt, rem_sz + 1, fmt, ap);
> > - va_end(ap);
> > -
> > - if (ret < 0) {
> > - env.log_buf[env.log_cnt] = '\0';
> > - fprintf(stderr, "failed to log w/ fmt '%s'\n", fmt);
> > - return;
> > - }
> > - }
> > -
> > - if (!rem_sz || ret > rem_sz) {
> > - size_t new_sz = env.log_cap * 3 / 2;
> > - char *new_buf;
> > -
> > - if (new_sz < 4096)
> > - new_sz = 4096;
> > - if (new_sz < ret + env.log_cnt)
> > - new_sz = ret + env.log_cnt;
> > -
> > - /* +1 for guaranteed space for terminating \0 */
> > - new_buf = realloc(env.log_buf, new_sz + 1);
> > - if (!new_buf) {
> > - fprintf(stderr, "failed to realloc log buffer: %d\n",
> > - errno);
> > - return;
> > - }
> > - env.log_buf = new_buf;
> > - env.log_cap = new_sz;
> > - goto try_again;
> > - }
> > -
> > - env.log_cnt += ret;
> > + vprintf(fmt, args);
> > }
> >
> > void test__printf(const char *fmt, ...)
> > @@ -477,6 +438,48 @@ static error_t parse_arg(int key, char *arg, struct argp_state *state)
> > return 0;
> > }
> >
> > +static void stdio_hijack(void)
> > +{
> > +#ifdef __GLIBC__
> > + if (env.verbose || (env.test && env.test->force_log)) {
>
> I just also realized that you don't need `(env.test &&
> env.test->force_log)` test. We hijack stdout/stderr before env.test is
> even set, so this does nothing anyways. Plus, force_log can be set in
> the middle of test/sub-test, yet we hijack stdout just once (or even
> if per-test), so it's still going to be "racy". Let's buffer output
> (unless it's env.verbose, which is important to not buffer because
> some tests will have huge output, when failing, so this allows to
> bypass using tons of memory for those, when debugging) and dump at the
> end.
Makes sense, will drop this test and resubmit along with a fix for '-v'
that Alexei discovered. Thanks!
> > + /* nothing to do, output to stdout by default */
> > + return;
> > + }
> > +
> > + /* stdout and stderr -> buffer */
> > + fflush(stdout);
> > +
> > + env.stdout = stdout;
> > + env.stderr = stderr;
> > +
> > + stdout = open_memstream(&env.log_buf, &env.log_cnt);
> > + if (!stdout) {
> > + stdout = env.stdout;
> > + perror("open_memstream");
> > + return;
> > + }
> > +
> > + stderr = stdout;
> > +#endif
> > +}
> > +
> > +static void stdio_restore(void)
> > +{
> > +#ifdef __GLIBC__
> > + if (stdout == env.stdout)
> > + return;
> > +
> > + fclose(stdout);
> > + free(env.log_buf);
> > +
> > + env.log_buf = NULL;
> > + env.log_cnt = 0;
> > +
> > + stdout = env.stdout;
> > + stderr = env.stderr;
> > +#endif
> > +}
> > +
> > int main(int argc, char **argv)
> > {
> > static const struct argp argp = {
> > @@ -496,6 +499,7 @@ int main(int argc, char **argv)
> >
> > env.jit_enabled = is_jit_enabled();
> >
> > + stdio_hijack();
> > for (i = 0; i < prog_test_cnt; i++) {
> > struct prog_test_def *test = &prog_test_defs[i];
> > int old_pass_cnt = pass_cnt;
> > @@ -523,13 +527,14 @@ int main(int argc, char **argv)
> >
> > dump_test_log(test, test->error_cnt);
> >
> > - printf("#%d %s:%s\n", test->test_num, test->test_name,
> > - test->error_cnt ? "FAIL" : "OK");
> > + fprintf(env.stdout, "#%d %s:%s\n",
> > + test->test_num, test->test_name,
> > + test->error_cnt ? "FAIL" : "OK");
> > }
> > + stdio_restore();
> > printf("Summary: %d/%d PASSED, %d FAILED\n",
> > env.succ_cnt, env.sub_succ_cnt, env.fail_cnt);
> >
> > - free(env.log_buf);
> > free(env.test_selector.num_set);
> > free(env.subtest_selector.num_set);
> >
> > diff --git a/tools/testing/selftests/bpf/test_progs.h b/tools/testing/selftests/bpf/test_progs.h
> > index afd14962456f..541f9eab5eed 100644
> > --- a/tools/testing/selftests/bpf/test_progs.h
> > +++ b/tools/testing/selftests/bpf/test_progs.h
> > @@ -56,9 +56,10 @@ struct test_env {
> > bool jit_enabled;
> >
> > struct prog_test_def *test;
> > + FILE *stdout;
> > + FILE *stderr;
> > char *log_buf;
> > size_t log_cnt;
> > - size_t log_cap;
> >
> > int succ_cnt; /* successful tests */
> > int sub_succ_cnt; /* successful sub-tests */
> > --
> > 2.22.0.770.g0f2c4a37fd-goog
> >
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