diff mbox series

[v2] syscalls/prctl08: New test for prctl() with PR_{SET, GET}_TIMERSLACK

Message ID 1564216031-2973-1-git-send-email-xuyang2018.jy@cn.fujitsu.com
State Changes Requested
Headers show
Series [v2] syscalls/prctl08: New test for prctl() with PR_{SET, GET}_TIMERSLACK | expand

Commit Message

Yang Xu July 27, 2019, 8:27 a.m. UTC 
Signed-off-by: Yang Xu <xuyang2018.jy@cn.fujitsu.com>
-----
v1->v2:
   1)remove useless struct member
   2)compare time should be (sleep + timer_slack) if time is not enough large
---
 include/lapi/prctl.h                       |   5 +
 runtest/syscalls                           |   1 +
 testcases/kernel/syscalls/prctl/.gitignore |   1 +
 testcases/kernel/syscalls/prctl/Makefile   |   1 +
 testcases/kernel/syscalls/prctl/prctl08.c  | 118 +++++++++++++++++++++
 5 files changed, 126 insertions(+)
 create mode 100644 testcases/kernel/syscalls/prctl/prctl08.c

Comments

Cyril Hrubis July 30, 2019, 9:07 a.m. UTC | #1 
Hi!
> +static struct tcase {
> +	unsigned long setvalue;
> +	unsigned long cmptime;
> +} tcases[] = {
> +	{1, 50000},
> +	{70000, 120000},
> +	{INT_MAX, 50000},
> +};
> +
> +static int proc_flag = 1;
> +
> +static void check_proc_ns(char *message, unsigned long value)
> +{
> +	unsigned long proc_value;
> +
> +	SAFE_FILE_SCANF(PROC_NS_PATH, "%lu", &proc_value);
> +	if (proc_value == value)
> +		tst_res(TPASS, "%s %s  got %lu expectedly",
> +				message, PROC_NS_PATH, proc_value);
> +	else
> +		tst_res(TFAIL, "%s %s expected %lu got %lu",
> +				message, PROC_NS_PATH, value, proc_value);
> +}
> +
> +static void check_get_timerslack(char *message, unsigned long value)
> +{
> +	TEST(prctl(PR_GET_TIMERSLACK));
> +	if ((unsigned long)TST_RET == value)
> +		tst_res(TPASS, "%s prctl(PR_GET_TIMERSLACK) got %lu expectedly",
> +				message, value);
> +	else
> +		tst_res(TFAIL, "%s prctl(PR_GET_TIMERSLACK) expected %lu got %lu",
> +				message, value, TST_RET);
> +
> +	if (proc_flag)
> +		check_proc_ns(message, value);
> +}
> +
> +static void verify_prctl(unsigned int n)
> +{
> +	struct tcase *tc = &tcases[n];
> +	int pid;
> +
> +	struct timespec timereq = { .tv_sec = 0, .tv_nsec = 50000 };
> +	struct timespec timecmp = { .tv_sec = 0, .tv_nsec = tc->cmptime};
> +
> +	TEST(prctl(PR_SET_TIMERSLACK, tc->setvalue));
> +	if (TST_RET == -1) {
> +		tst_res(TFAIL | TTERRNO, "prctl(PR_SET_TIMERSLACK, %lu) failed",
> +				tc->setvalue);
> +		return;
> +	}
> +	tst_res(TPASS, "prctl(PR_SET_TIMERSLACK, %lu) success", tc->setvalue);
> +
> +	pid = SAFE_FORK();
> +	if (pid == 0) {
> +		check_get_timerslack("child process", tc->setvalue);
> +		/* A value of 0 means using default */
> +		prctl(PR_SET_TIMERSLACK, 0);

Why do we reset the slack before the measurements?

> +		check_get_timerslack("After set 0, child process", tc->setvalue);
> +
> +		tst_timer_start(CLOCK_MONOTONIC);
> +		TEST(nanosleep(&timereq, NULL));
> +		tst_timer_stop();
> +
> +		if (tst_timespec_lt(tst_timer_elapsed(), timecmp))
> +			tst_brk(TFAIL, "nanosleep() slept less than timecmp");

I do not get what we are trying to assert here.

As far as I understand it the timer slack is a way how to inform kernel
that it's okay if the timers are slightly less precise. However the
timer still can fire somewhere between sleep time and sleep time +
slack, or even maybe later if the system is under load.

BTW we do have a formula that tries to compute maximal time the timers
should sleep based on timer slack in lib/tst_timer_test.c but even with
that we have to take more samples and compute truncated mean because
single short sleep may be delayed unless it's a RT kernel...

> +		tst_res(TPASS, "nanosleep() slept more than timecmp, %llius",
> +				tst_timer_elapsed_us());
> +		exit(0);
> +	}
> +}
> +
> +static void setup(void)
> +{
> +	if (access(PROC_NS_PATH, F_OK) == -1) {
> +		tst_res(TCONF, "proc doesn't support timerslack_ns interface");
> +		proc_flag = 0;
> +	}
> +}
> +
> +static struct tst_test test = {
> +	.setup = setup,
> +	.test = verify_prctl,
> +	.tcnt = ARRAY_SIZE(tcases),
> +	.forks_child = 1,
> +};
> -- 
> 2.18.1
> 
> 
> 
> 
> -- 
> Mailing list info: https://lists.linux.it/listinfo/ltp
Yang Xu July 30, 2019, 10:01 a.m. UTC | #2 
> Hi!
>> +static struct tcase {
>> +	unsigned long setvalue;
>> +	unsigned long cmptime;
>> +} tcases[] = {
>> +	{1, 50000},
>> +	{70000, 120000},
>> +	{INT_MAX, 50000},
>> +};
>> +
>> +static int proc_flag = 1;
>> +
>> +static void check_proc_ns(char *message, unsigned long value)
>> +{
>> +	unsigned long proc_value;
>> +
>> +	SAFE_FILE_SCANF(PROC_NS_PATH, "%lu",&proc_value);
>> +	if (proc_value == value)
>> +		tst_res(TPASS, "%s %s  got %lu expectedly",
>> +				message, PROC_NS_PATH, proc_value);
>> +	else
>> +		tst_res(TFAIL, "%s %s expected %lu got %lu",
>> +				message, PROC_NS_PATH, value, proc_value);
>> +}
>> +
>> +static void check_get_timerslack(char *message, unsigned long value)
>> +{
>> +	TEST(prctl(PR_GET_TIMERSLACK));
>> +	if ((unsigned long)TST_RET == value)
>> +		tst_res(TPASS, "%s prctl(PR_GET_TIMERSLACK) got %lu expectedly",
>> +				message, value);
>> +	else
>> +		tst_res(TFAIL, "%s prctl(PR_GET_TIMERSLACK) expected %lu got %lu",
>> +				message, value, TST_RET);
>> +
>> +	if (proc_flag)
>> +		check_proc_ns(message, value);
>> +}
>> +
>> +static void verify_prctl(unsigned int n)
>> +{
>> +	struct tcase *tc =&tcases[n];
>> +	int pid;
>> +
>> +	struct timespec timereq = { .tv_sec = 0, .tv_nsec = 50000 };
>> +	struct timespec timecmp = { .tv_sec = 0, .tv_nsec = tc->cmptime};
>> +
>> +	TEST(prctl(PR_SET_TIMERSLACK, tc->setvalue));
>> +	if (TST_RET == -1) {
>> +		tst_res(TFAIL | TTERRNO, "prctl(PR_SET_TIMERSLACK, %lu) failed",
>> +				tc->setvalue);
>> +		return;
>> +	}
>> +	tst_res(TPASS, "prctl(PR_SET_TIMERSLACK, %lu) success", tc->setvalue);
>> +
>> +	pid = SAFE_FORK();
>> +	if (pid == 0) {
>> +		check_get_timerslack("child process", tc->setvalue);
>> +		/* A value of 0 means using default */
>> +		prctl(PR_SET_TIMERSLACK, 0);
> Why do we reset the slack before the measurements?
Hi Cyril

    I reset it because  I want to test whether default timer_slack in child process is the same as the current value
of the creating thread.

I also sent a patch about PR_SET_TIMERSLACK to man-page, as below:
https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/commit/?id=c14f79303f2885f7f4f4bf0d63922551b520a4b8



>> +		check_get_timerslack("After set 0, child process", tc->setvalue);
>> +
>> +		tst_timer_start(CLOCK_MONOTONIC);
>> +		TEST(nanosleep(&timereq, NULL));
>> +		tst_timer_stop();
>> +
>> +		if (tst_timespec_lt(tst_timer_elapsed(), timecmp))
>> +			tst_brk(TFAIL, "nanosleep() slept less than timecmp");
> I do not get what we are trying to assert here.
>
> As far as I understand it the timer slack is a way how to inform kernel
> that it's okay if the timers are slightly less precise. However the
> timer still can fire somewhere between sleep time and sleep time +
> slack, or even maybe later if the system is under load.
Yes. timer still can fire somewhere in [sleep, sleep+slack] range even later.

> BTW we do have a formula that tries to compute maximal time the timers
> should sleep based on timer slack in lib/tst_timer_test.c but even with
> that we have to take more samples and compute truncated mean because
> single short sleep may be delayed unless it's a RT kernel...
>
Yes . Agree. Single short sleep may be delayed and I will take more samples.

>> +		tst_res(TPASS, "nanosleep() slept more than timecmp, %llius",
>> +				tst_timer_elapsed_us());
>> +		exit(0);
>> +	}
>> +}
>> +
>> +static void setup(void)
>> +{
>> +	if (access(PROC_NS_PATH, F_OK) == -1) {
>> +		tst_res(TCONF, "proc doesn't support timerslack_ns interface");
>> +		proc_flag = 0;
>> +	}
>> +}
>> +
>> +static struct tst_test test = {
>> +	.setup = setup,
>> +	.test = verify_prctl,
>> +	.tcnt = ARRAY_SIZE(tcases),
>> +	.forks_child = 1,
>> +};
>> -- 
>> 2.18.1
>>
>>
>>
>>
>> -- 
>> Mailing list info: https://lists.linux.it/listinfo/ltp
diff mbox series

Patch

diff --git a/include/lapi/prctl.h b/include/lapi/prctl.h
index 8ee492259..0b4e196c3 100644
--- a/include/lapi/prctl.h
+++ b/include/lapi/prctl.h
@@ -19,6 +19,11 @@ 
 # define PR_SET_SECCOMP  22
 #endif
 
+#ifndef PR_SET_TIMERSLACK
+# define PR_SET_TIMERSLACK 29
+# define PR_GET_TIMERSLACK 30
+#endif
+
 #ifndef PR_SET_CHILD_SUBREAPER
 # define PR_SET_CHILD_SUBREAPER	36
 # define PR_GET_CHILD_SUBREAPER	37
diff --git a/runtest/syscalls b/runtest/syscalls
index 0114b002b..48836f422 100644
--- a/runtest/syscalls
+++ b/runtest/syscalls
@@ -872,6 +872,7 @@  prctl04 prctl04
 prctl05 prctl05
 prctl06 prctl06
 prctl07 prctl07
+prctl08 prctl08
 
 pread01 pread01
 pread01_64 pread01_64
diff --git a/testcases/kernel/syscalls/prctl/.gitignore b/testcases/kernel/syscalls/prctl/.gitignore
index 2178db366..fe36a8e0f 100644
--- a/testcases/kernel/syscalls/prctl/.gitignore
+++ b/testcases/kernel/syscalls/prctl/.gitignore
@@ -6,3 +6,4 @@ 
 /prctl06
 /prctl06_execve
 /prctl07
+/prctl08
diff --git a/testcases/kernel/syscalls/prctl/Makefile b/testcases/kernel/syscalls/prctl/Makefile
index cf19507c0..d3c41ff4e 100644
--- a/testcases/kernel/syscalls/prctl/Makefile
+++ b/testcases/kernel/syscalls/prctl/Makefile
@@ -21,5 +21,6 @@  top_srcdir		?= ../../../..
 include $(top_srcdir)/include/mk/testcases.mk
 
 prctl07: LDLIBS += $(CAP_LIBS)
+prctl08: LDLIBS+=-lrt
 
 include $(top_srcdir)/include/mk/generic_leaf_target.mk
diff --git a/testcases/kernel/syscalls/prctl/prctl08.c b/testcases/kernel/syscalls/prctl/prctl08.c
new file mode 100644
index 000000000..92b9bfe41
--- /dev/null
+++ b/testcases/kernel/syscalls/prctl/prctl08.c
@@ -0,0 +1,118 @@ 
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2019 FUJITSU LIMITED. All rights reserved.
+ * Author: Yang Xu <xuyang2018.jy@cn.fujitsu.com>
+ *
+ * Test PR_GET_TIMERSLACK and PR_SET_TIMERSLACK of prctl(2).
+ * 1)Each thread has two associated timer slack values: a "default"
+ *   value, and a "current" value. PR_SET_TIMERSLACK sets the "current"
+ *   timer slack value for the calling thread.
+ * 2)When a new thread is created, the two timer slack values are made
+ *   the same as the "current" value of the creating thread.
+ * 3)The maximum timer slack value is ULONG_MAX. On 32bit machines, it
+ *   is a valid value(about 4s). On 64bit machines, it is about 500 years
+ *   and no person will set this over 4s.  prctl return value is int, so
+ *   we test themaximum value is INT_MAX.
+ * 4)we also check /proc/[pid]/timerslack_ns if it is supported.
+ */
+
+#include <sys/prctl.h>
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <linux/limits.h>
+#include "lapi/syscalls.h"
+#include "lapi/prctl.h"
+#include "tst_timer.h"
+#include "tst_test.h"
+
+#define PROC_NS_PATH "/proc/self/timerslack_ns"
+
+static struct tcase {
+	unsigned long setvalue;
+	unsigned long cmptime;
+} tcases[] = {
+	{1, 50000},
+	{70000, 120000},
+	{INT_MAX, 50000},
+};
+
+static int proc_flag = 1;
+
+static void check_proc_ns(char *message, unsigned long value)
+{
+	unsigned long proc_value;
+
+	SAFE_FILE_SCANF(PROC_NS_PATH, "%lu", &proc_value);
+	if (proc_value == value)
+		tst_res(TPASS, "%s %s  got %lu expectedly",
+				message, PROC_NS_PATH, proc_value);
+	else
+		tst_res(TFAIL, "%s %s expected %lu got %lu",
+				message, PROC_NS_PATH, value, proc_value);
+}
+
+static void check_get_timerslack(char *message, unsigned long value)
+{
+	TEST(prctl(PR_GET_TIMERSLACK));
+	if ((unsigned long)TST_RET == value)
+		tst_res(TPASS, "%s prctl(PR_GET_TIMERSLACK) got %lu expectedly",
+				message, value);
+	else
+		tst_res(TFAIL, "%s prctl(PR_GET_TIMERSLACK) expected %lu got %lu",
+				message, value, TST_RET);
+
+	if (proc_flag)
+		check_proc_ns(message, value);
+}
+
+static void verify_prctl(unsigned int n)
+{
+	struct tcase *tc = &tcases[n];
+	int pid;
+
+	struct timespec timereq = { .tv_sec = 0, .tv_nsec = 50000 };
+	struct timespec timecmp = { .tv_sec = 0, .tv_nsec = tc->cmptime};
+
+	TEST(prctl(PR_SET_TIMERSLACK, tc->setvalue));
+	if (TST_RET == -1) {
+		tst_res(TFAIL | TTERRNO, "prctl(PR_SET_TIMERSLACK, %lu) failed",
+				tc->setvalue);
+		return;
+	}
+	tst_res(TPASS, "prctl(PR_SET_TIMERSLACK, %lu) success", tc->setvalue);
+
+	pid = SAFE_FORK();
+	if (pid == 0) {
+		check_get_timerslack("child process", tc->setvalue);
+		/* A value of 0 means using default */
+		prctl(PR_SET_TIMERSLACK, 0);
+		check_get_timerslack("After set 0, child process", tc->setvalue);
+
+		tst_timer_start(CLOCK_MONOTONIC);
+		TEST(nanosleep(&timereq, NULL));
+		tst_timer_stop();
+
+		if (tst_timespec_lt(tst_timer_elapsed(), timecmp))
+			tst_brk(TFAIL, "nanosleep() slept less than timecmp");
+
+		tst_res(TPASS, "nanosleep() slept more than timecmp, %llius",
+				tst_timer_elapsed_us());
+		exit(0);
+	}
+}
+
+static void setup(void)
+{
+	if (access(PROC_NS_PATH, F_OK) == -1) {
+		tst_res(TCONF, "proc doesn't support timerslack_ns interface");
+		proc_flag = 0;
+	}
+}
+
+static struct tst_test test = {
+	.setup = setup,
+	.test = verify_prctl,
+	.tcnt = ARRAY_SIZE(tcases),
+	.forks_child = 1,
+};