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

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Message-Id: <20240818000620.ba9a93ccb82bc48cd3155cc7@kernel.org>
Date: Sun, 18 Aug 2024 00:06:20 +0900
From: Masami Hiramatsu (Google) <mhiramat@...nel.org>
To: Shuah Khan <skhan@...uxfoundation.org>
Cc: Steven Rostedt <rostedt@...dmis.org>, Shuah Khan <shuah@...nel.org>, 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
Subject: Re: [PATCH v4 3/3] selftests/tracing: Add hist poll() support test

On Fri, 16 Aug 2024 08:04:41 -0600
Shuah Khan <skhan@...uxfoundation.org> wrote:

> On 8/15/24 20:31, 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 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.
> 
Oops, indeed.

> With this fixed
> 
> Reviewed-by: Shuah Khan <skhan@...uxfoundation.org>

Thanks!

> 
> thanks,
> -- Shuah


-- 
Masami Hiramatsu (Google) <mhiramat@...nel.org>