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Message-ID: <2c13840e-2717-4f88-b613-f6a770be2d75@linuxfoundation.org>
Date: Wed, 14 Aug 2024 05:38:24 -0600
From: Shuah Khan <skhan@...uxfoundation.org>
To: "Masami Hiramatsu (Google)" <mhiramat@...nel.org>,
Steven Rostedt <rostedt@...dmis.org>, Shuah Khan <shuah@...nel.org>
Cc: Tom Zanussi <zanussi@...nel.org>,
Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
linux-kselftest@...r.kernel.org, Shuah Khan <skhan@...uxfoundation.org>
Subject: 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@...nel.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@...nel.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
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