[LTP] [PATCH v1] starvation.c: New case for sched starvation

[Wei Gao]

Signed-off-by: Wei Gao <wegao@suse.com>

Add scheduller thread starvation test case base following link:
https://lwn.net/ml/linux-kernel/9fd2c37a05713c206dcbd5866f67ce779f315e9e.camel@gmx.de/
---
 runtest/sched                                 |  1 +
 .../kernel/sched/cfs-scheduler/.gitignore     |  1 +
 .../kernel/sched/cfs-scheduler/starvation.c   | 97 +++++++++++++++++++
 3 files changed, 99 insertions(+)
 create mode 100644 testcases/kernel/sched/cfs-scheduler/starvation.c

diff --git a/runtest/sched b/runtest/sched
index 592898723..172fe4174 100644
--- a/runtest/sched
+++ b/runtest/sched
@@ -9,6 +9,7 @@ trace_sched01		trace_sched -c 1
 cfs_bandwidth01 cfs_bandwidth01 -i 5
 hackbench01 hackbench 50 process 1000
 hackbench02 hackbench 20 thread 1000
+starvation starvation
 
 sched_cli_serv run_sched_cliserv.sh
 # Run this stress test for 2 minutes
diff --git a/testcases/kernel/sched/cfs-scheduler/.gitignore b/testcases/kernel/sched/cfs-scheduler/.gitignore
index c5dacd6ef..e86178f80 100644
--- a/testcases/kernel/sched/cfs-scheduler/.gitignore
+++ b/testcases/kernel/sched/cfs-scheduler/.gitignore
@@ -1,2 +1,3 @@
 /hackbench
 cfs_bandwidth01
+/starvation
diff --git a/testcases/kernel/sched/cfs-scheduler/starvation.c b/testcases/kernel/sched/cfs-scheduler/starvation.c
new file mode 100644
index 000000000..74bffd741
--- /dev/null
+++ b/testcases/kernel/sched/cfs-scheduler/starvation.c
@@ -0,0 +1,97 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* Copyright 2023 Mike Galbraith <efault-AT-gmx.de> */
+/*\
+ *
+ * [Description]
+ *
+ * Thread starvation test.
+ * This case copy from following link:
+ * https://lwn.net/ml/linux-kernel/9fd2c37a05713c206dcbd5866f67ce779f315e9e.camel@gmx.de/
+ *
+ */
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <signal.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <stdlib.h>
+#include <sched.h>
+
+#include "tst_test.h"
+
+static unsigned long loop = 10000000;
+
+static int wait_for_pid(pid_t pid)
+{
+	int status, ret;
+
+again:
+	ret = waitpid(pid, &status, 0);
+	if (ret == -1) {
+		if (errno == EINTR)
+			goto again;
+
+		return -1;
+	}
+
+	if (WIFSIGNALED(status))
+		return 0;
+
+	return -1;
+}
+
+static void setup(void)
+{
+	cpu_set_t mask;
+
+	CPU_ZERO(&mask);
+
+	CPU_SET(0, &mask);
+
+	TST_EXP_POSITIVE(sched_setaffinity(0, sizeof(mask), &mask));
+}
+
+static void handler(void)
+{
+	if (loop > 0)
+		--loop;
+}
+
+static int child(void)
+{
+	pid_t ppid = getppid();
+
+	TST_CHECKPOINT_WAIT(0);
+
+	while (1)
+		kill(ppid, SIGUSR1);
+}
+
+static void do_test(void)
+{
+	pid_t child_pid;
+
+	child_pid = SAFE_FORK();
+
+	if (!child_pid)
+		child();
+
+	SAFE_SIGNAL(SIGUSR1, handler);
+	TST_CHECKPOINT_WAKE(0);
+
+	while (loop)
+		sleep(1);
+
+	kill(child_pid, SIGTERM);
+	TST_EXP_PASS(wait_for_pid(child_pid));
+}
+
+static struct tst_test test = {
+	.test_all = do_test,
+	.setup = setup,
+	.forks_child = 1,
+	.needs_checkpoints = 1,
+	.max_runtime = 120,
+};
-- 
2.35.3