[PATCH V2 12/12] selftests, powerpc: Add thread based stress test for DSCR sysfs interfaces

[Anshuman Khandual <khandual@linux.vnet.ibm.com>]

This patch adds a test to update the system wide DSCR value repeatedly
and then verifies that any thread on any given CPU on the system must
be able to see the same DSCR value whether its is being read through
the problem state based SPR or the privilege state based SPR.

Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
---
 tools/testing/selftests/powerpc/dscr/Makefile      |   2 +-
 .../powerpc/dscr/dscr_sysfs_thread_test.c          | 114 +++++++++++++++++++++
 2 files changed, 115 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/powerpc/dscr/dscr_sysfs_thread_test.c

diff --git a/tools/testing/selftests/powerpc/dscr/Makefile b/tools/testing/selftests/powerpc/dscr/Makefile
index fada526..834ef88 100644
--- a/tools/testing/selftests/powerpc/dscr/Makefile
+++ b/tools/testing/selftests/powerpc/dscr/Makefile
@@ -1,6 +1,6 @@
 PROGS := dscr_default_test dscr_explicit_test dscr_user_test	\
 	 dscr_inherit_test dscr_inherit_exec_test		\
-	 dscr_sysfs_test
+	 dscr_sysfs_test dscr_sysfs_thread_test
 
 CFLAGS := $(CFLAGS) -lpthread
 
diff --git a/tools/testing/selftests/powerpc/dscr/dscr_sysfs_thread_test.c b/tools/testing/selftests/powerpc/dscr/dscr_sysfs_thread_test.c
new file mode 100644
index 0000000..95a4304
--- /dev/null
+++ b/tools/testing/selftests/powerpc/dscr/dscr_sysfs_thread_test.c
@@ -0,0 +1,114 @@
+/*
+ * POWER Data Stream Control Register (DSCR) sysfs thread test
+ *
+ * This test updates the system wide DSCR default value through
+ * sysfs interface which should then update all the CPU specific
+ * DSCR default values which must also be then visible to threads
+ * executing on individual CPUs on the system.
+ *
+ * Copyright (C) 2015 Anshuman Khandual <khandual@linux.vnet.ibm.com>, IBM
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+#define _GNU_SOURCE
+#include "dscr.h"
+
+static pthread_mutex_t lock;	/* Pthread lock */
+static cpu_set_t cpuset;	/* Thread cpu set */
+static int target;		/* Thread target cpu */
+static unsigned long *result;	/* Thread exit status array */
+
+static void *test_thread_dscr(void *in)
+{
+	unsigned long cur_dscr, cur_dscr_usr;
+	unsigned long val = (unsigned long)in;
+
+	pthread_mutex_lock(&lock);
+	target++;
+	if (target == sysconf(_SC_NPROCESSORS_ONLN))
+		target =  0;
+	CPU_ZERO(&cpuset);
+	CPU_SET(target, &cpuset);
+
+	if (sched_setaffinity(0, sizeof(cpuset), &cpuset)) {
+		perror("sched_settarget_cpu() failed\n");
+		pthread_mutex_unlock(&lock);
+		result[target] = 1;
+		pthread_exit(&result[target]);
+	}
+	pthread_mutex_unlock(&lock);
+
+	cur_dscr = get_dscr();
+	cur_dscr_usr = get_dscr_usr();
+
+	if (val != cur_dscr) {
+		printf("[cpu %d] Kernel DSCR should be %ld but is %ld\n",
+					sched_getcpu(), val, cur_dscr);
+		result[target] = 1;
+		pthread_exit(&result[target]);
+	}
+
+	if (val != cur_dscr_usr) {
+		printf("[cpu %d] User DSCR should be %ld but is %ld\n",
+					sched_getcpu(), val, cur_dscr_usr);
+		result[target] = 1;
+		pthread_exit(&result[target]);
+	}
+	result[target] = 0;
+	pthread_exit(&result[target]);
+}
+
+static int check_cpu_dscr_thread(unsigned long val)
+{
+	pthread_t threads[sysconf(_SC_NPROCESSORS_ONLN)];
+	unsigned long *status[sysconf(_SC_NPROCESSORS_ONLN)];
+	unsigned long i;
+
+	for (i = 0; i < sysconf(_SC_NPROCESSORS_ONLN); i++) {
+		if (pthread_create(&threads[i], NULL,
+				test_thread_dscr, (void *)val)) {
+			perror("pthread_create() failed\n");
+			return 1;
+		}
+	}
+
+	for (i = 0; i < sysconf(_SC_NPROCESSORS_ONLN); i++) {
+		if (pthread_join(threads[i], (void **)&(status[i]))) {
+			perror("pthread_join() failed\n");
+			return 1;
+		}
+
+		if (*status[i]) {
+			printf(" %ldth thread join failed with %ld\n",
+							i, *status[i]);
+			return 1;
+		}
+	}
+	return 0;
+}
+
+int test_body(void)
+{
+	int i, j;
+
+	result = malloc(sizeof(unsigned long) * sysconf(_SC_NPROCESSORS_ONLN));
+	pthread_mutex_init(&lock, NULL);
+	target = 0;
+	for (i = 0; i < COUNT; i++) {
+		for (j = 0; j < DSCR_MAX; j++) {
+			set_default_dscr(j);
+			if (check_cpu_dscr_thread(j))
+				return 1;
+		}
+	}
+	free(result);
+	return 0;
+}
+
+int main(int argc, char *argv[])
+{
+	return test_harness(test_body, "dscr_sysfs_thread_test");
+}
-- 
1.9.3