Re: [PATCH v3 3/3] selftests/tracing: Add hist poll() support test

On 8/13/24 18:11, Masami Hiramatsu (Google) wrote:

From: Masami Hiramatsu (Google) mhiramat@kernel.org

Add a testcase for poll() on hist file. This introduces a helper binary to the ftracetest, because there is no good way to reliably execute poll() on hist file.

Signed-off-by: Masami Hiramatsu (Google) mhiramat@kernel.org

Changes in v2:

• Update poll command to support both of POLLIN and POLLPRI, and timeout.
• Identify unsupported stable kernel if poll-in returns soon.
• Test both of POLLIN and POLLPRI.

---

tools/testing/selftests/ftrace/Makefile | 2 + tools/testing/selftests/ftrace/poll.c | 62 +++++++++++++++++ .../ftrace/test.d/trigger/trigger-hist-poll.tc | 74 ++++++++++++++++++++ 3 files changed, 138 insertions(+) create mode 100644 tools/testing/selftests/ftrace/poll.c create mode 100644 tools/testing/selftests/ftrace/test.d/trigger/trigger-hist-poll.tc

diff --git a/tools/testing/selftests/ftrace/Makefile b/tools/testing/selftests/ftrace/Makefile index a1e955d2de4c..49d96bb16355 100644 --- a/tools/testing/selftests/ftrace/Makefile +++ b/tools/testing/selftests/ftrace/Makefile @@ -6,4 +6,6 @@ TEST_PROGS := ftracetest-ktap TEST_FILES := test.d settings EXTRA_CLEAN := $(OUTPUT)/logs/* +TEST_GEN_PROGS = poll

• include ../lib.mk

diff --git a/tools/testing/selftests/ftrace/poll.c b/tools/testing/selftests/ftrace/poll.c new file mode 100644 index 000000000000..8003a59fe042 --- /dev/null +++ b/tools/testing/selftests/ftrace/poll.c @@ -0,0 +1,62 @@ +// SPDX-License-Identifier: GPL-2.0 +/*

• • Simple poll on a file.
• • Copyright (c) 2024 Google LLC.
• */

+#include <errno.h> +#include <fcntl.h> +#include <poll.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h>

+#define BUFSIZE 4096

+/*

• • Usage:
• • poll <in|pri> <FILE> [timeout]
• */

+int main(int argc, char *argv[]) +{

• struct pollfd pfd;
• char buf[BUFSIZE];
• int timeout = -1;
• int ret;
• if (argc < 3)

• return -1;
  

• if (!strcmp(argv[1], "in"))

• pfd.events = POLLIN;
  

• else if (!strcmp(argv[1], "pri"))

• pfd.events = POLLPRI;
  

• pfd.fd = open(argv[2], O_RDONLY);
• if (pfd.fd < 0) {

• perror("open");
  

• return -1;
  

• }
• if (argc == 4)

• timeout = atoi(argv[3]);
  

This code can be simpler and more maintainable using getopt. Any reason why you didn't use it?

• /* Reset poll by read if POLLIN is specified. */
• if (pfd.events & POLLIN)

• do {} while (read(pfd.fd, buf, BUFSIZE) == BUFSIZE);
  

• ret = poll(&pfd, 1, timeout);
• if (ret < 0 && errno != EINTR) {

• perror("poll")> +		return -1;
  

• }
• close(pfd.fd);
• /* If timeout happned, return code is 0 */

Spelling - happened

• if (ret == 0)

• return 1;
  

• return 0;

+} diff --git a/tools/testing/selftests/ftrace/test.d/trigger/trigger-hist-poll.tc b/tools/testing/selftests/ftrace/test.d/trigger/trigger-hist-poll.tc new file mode 100644 index 000000000000..53bea74e2234 --- /dev/null +++ b/tools/testing/selftests/ftrace/test.d/trigger/trigger-hist-poll.tc @@ -0,0 +1,74 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 +# description: event trigger - test poll wait on histogram +# requires: set_event events/sched/sched_process_free/trigger events/sched/sched_process_free/hist +# flags: instance

+POLL=${FTRACETEST_ROOT}/poll

+if [ ! -x ${POLL} ]; then

• echo "poll program is not compiled!"
• exit_unresolved

+fi

+EVENT=events/sched/sched_process_free/

+# Check poll ops is supported. Before implementing poll on hist file, it +# returns soon with POLLIN | POLLOUT, but not POLLPRI.

+# This must wait >1 sec and return 1 (timeout). +set +e +${POLL} in ${EVENT}/hist 1000 +ret=$? +set -e +if [ ${ret} != 1 ]; then

• echo "poll on hist file is not supported"
• exit_unsupported

+fi

+# Test POLLIN +echo > trace +echo "hist:key=comm" > ${EVENT}/trigger +echo 1 > ${EVENT}/enable

+# This sleep command will exit after 2 seconds. +sleep 2 & +BGPID=$! +# if timeout happens, poll returns 1. +${POLL} in ${EVENT}/hist 4000 +echo 0 > tracing_on

+if [ -d /proc/${BGPID} ]; then

• echo "poll exits too soon"
• kill -KILL ${BGPID} ||:
• exit_fail

+fi

+if ! grep -qw "sleep" trace; then

• echo "poll exits before event happens"
• exit_fail

+fi

+# Test POLLPRI +echo > trace +echo 1 > tracing_on

+# This sleep command will exit after 2 seconds. +sleep 2 & +BGPID=$! +# if timeout happens, poll returns 1. +${POLL} pri ${EVENT}/hist 4000 +echo 0 > tracing_on

+if [ -d /proc/${BGPID} ]; then

• echo "poll exits too soon"
• kill -KILL ${BGPID} ||:
• exit_fail

+fi

+if ! grep -qw "sleep" trace; then

• echo "poll exits before event happens"
• exit_fail

+fi

+exit_pass

thanks, -- Shuah