Re: [PATCH v4 3/3] selftests/tracing: Add hist poll() support test

[Shuah Khan <skhan@linuxfoundation.org>]

On 8/15/24 20:31, 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 v4:
>    - Use getopt() in poll.c (command options are changed)
>    - Update test code according to the new command options.
>   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              |   74 ++++++++++++++++++++
>   .../ftrace/test.d/trigger/trigger-hist-poll.tc     |   74 ++++++++++++++++++++
>   3 files changed, 150 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..584f159654b1
> --- /dev/null
> +++ b/tools/testing/selftests/ftrace/poll.c
> @@ -0,0 +1,74 @@
> +// 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 [-I|-P] [-t timeout] FILE
> + */
> +int main(int argc, char *argv[])
> +{
> +	struct pollfd pfd = {.events = POLLIN};
> +	char buf[BUFSIZE];
> +	int timeout = -1;
> +	int ret, opt;
> +
> +	while ((opt = getopt(argc, argv, "IPt:")) != -1) {
> +		switch (opt) {
> +		case 'I':
> +			pfd.events = POLLIN;
> +			break;
> +		case 'P':
> +			pfd.events = POLLPRI;
> +			break;
> +		case 't':
> +			timeout = atoi(optarg);
> +			break;
> +		default:
> +			fprintf(stderr, "Usage: %s [-I|-P] [-t timeout] FILE\n",
> +				argv[0]);
> +			return -1;
> +		}
> +	}
> +	if (optind >= argc) {
> +		fprintf(stderr, "Error: Polling file is not specified\n");
> +		return -1;
> +	}
> +
> +	pfd.fd = open(argv[optind], O_RDONLY);
> +	if (pfd.fd < 0) {
> +		fprintf(stderr, "failed to open %s", argv[optind]);
> +		perror("open");
> +		return -1;
> +	}
> +
> +	/* 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 */

Looks like you missed this one :) Otherwise looks good to me.

With this fixed

Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>

thanks,
-- Shuah