perf test: Use a single fd for the child process out/err

Switch from dumping err then out, to a single file descriptor for both
of them. This allows the err and output to be correctly interleaved in
verbose output.

Fixes: b482f5f8e0168f1e ("perf tests: Add option to run tests in parallel")
Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Disha Goel <disgoel@linux.ibm.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: K Prateek Nayak <kprateek.nayak@amd.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Yicong Yang <yangyicong@hisilicon.com>
Link: https://lore.kernel.org/r/20240301074639.2260708-3-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/tests/builtin-test.c b/tools/perf/tests/builtin-test.c
index d13ee7683d9d835495eeaf3413c3cea1dd56c313..e05b370b1e2b1d7b1e97662600a9a4c60ef22965 100644 (file)
--- a/tools/perf/tests/builtin-test.c
+++ b/tools/perf/tests/builtin-test.c
@@ -274,11 +274,8 @@ static int finish_test(struct child_test *child_test, int width)
        struct test_suite *t = child_test->test;
        int i = child_test->test_num;
        int subi = child_test->subtest;
-       int out = child_test->process.out;
        int err = child_test->process.err;
-       bool out_done = out <= 0;
        bool err_done = err <= 0;
-       struct strbuf out_output = STRBUF_INIT;
        struct strbuf err_output = STRBUF_INIT;
        int ret;
 
@@ -290,11 +287,9 @@ static int finish_test(struct child_test *child_test, int width)
                pr_info("%3d: %-*s:\n", i + 1, width, test_description(t, -1));
 
        /*
-        * Busy loop reading from the child's stdout and stderr that are set to
-        * be non-blocking until EOF.
+        * Busy loop reading from the child's stdout/stderr that are set to be
+        * non-blocking until EOF.
         */
-       if (!out_done)
-               fcntl(out, F_SETFL, O_NONBLOCK);
        if (!err_done)
                fcntl(err, F_SETFL, O_NONBLOCK);
        if (verbose > 1) {
@@ -303,11 +298,8 @@ static int finish_test(struct child_test *child_test, int width)
                else
                        pr_info("%3d: %s:\n", i + 1, test_description(t, -1));
        }
-       while (!out_done || !err_done) {
-               struct pollfd pfds[2] = {
-                       { .fd = out,
-                         .events = POLLIN | POLLERR | POLLHUP | POLLNVAL,
-                       },
+       while (!err_done) {
+               struct pollfd pfds[1] = {
                        { .fd = err,
                          .events = POLLIN | POLLERR | POLLHUP | POLLNVAL,
                        },
@@ -317,21 +309,7 @@ static int finish_test(struct child_test *child_test, int width)
 
                /* Poll to avoid excessive spinning, timeout set for 1000ms. */
                poll(pfds, ARRAY_SIZE(pfds), /*timeout=*/1000);
-               if (!out_done && pfds[0].revents) {
-                       errno = 0;
-                       len = read(out, buf, sizeof(buf) - 1);
-
-                       if (len <= 0) {
-                               out_done = errno != EAGAIN;
-                       } else {
-                               buf[len] = '\0';
-                               if (verbose > 1)
-                                       fprintf(stdout, "%s", buf);
-                               else
-                                       strbuf_addstr(&out_output, buf);
-                       }
-               }
-               if (!err_done && pfds[1].revents) {
+               if (!err_done && pfds[0].revents) {
                        errno = 0;
                        len = read(err, buf, sizeof(buf) - 1);
 
@@ -354,14 +332,10 @@ static int finish_test(struct child_test *child_test, int width)
                        pr_info("%3d.%1d: %s:\n", i + 1, subi + 1, test_description(t, subi));
                else
                        pr_info("%3d: %s:\n", i + 1, test_description(t, -1));
-               fprintf(stdout, "%s", out_output.buf);
                fprintf(stderr, "%s", err_output.buf);
        }
-       strbuf_release(&out_output);
        strbuf_release(&err_output);
        print_test_result(t, i, subi, ret, width);
-       if (out > 0)
-               close(out);
        if (err > 0)
                close(err);
        return 0;
@@ -394,6 +368,7 @@ static int start_test(struct test_suite *test, int i, int subi, struct child_tes
                (*child)->process.no_stdout = 1;
                (*child)->process.no_stderr = 1;
        } else {
+               (*child)->process.stdout_to_stderr = 1;
                (*child)->process.out = -1;
                (*child)->process.err = -1;
        }