iio: proximity: isl29501: Fix return type of isl29501_register_writegrafted

isl29501_register_write() was returning a u32 instead of an int.
Since the function returns negative error codes (such as -ERANGE or
return values from i2c_smbus_write_byte_data()), returning an unsigned
integer type prevents callers from correctly checking for negative error
conditions.

Fix this by changing the function return type from u32 to int.

This was found through manual code review.

Fixes: 1c28799257bc ("iio: light: isl29501: Add support for the ISL29501 ToF sensor.")
Signed-off-by: Salah Triki <salah.triki@gmail.com>
Reviewed-by: Joshua Crofts <joshua.crofts1@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Jonathan Cameron <jonathan.cameron@oss.qualcomm.com>

1 files changed, 153 insertions, 0 deletions

diff --git a/lib/tests/test_ratelimit.c b/lib/tests/test_ratelimit.c
new file mode 100644
index 000000000..e244f8cd4
--- /dev/null
+++ b/lib/tests/test_ratelimit.c
@@ -0,0 +1,153 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <kunit/test.h>
+
+#include <linux/ratelimit.h>
+#include <linux/module.h>
+#include <linux/kthread.h>
+#include <linux/cpumask.h>
+
+/* a simple boot-time regression test */
+
+#define TESTRL_INTERVAL (5 * HZ)
+static DEFINE_RATELIMIT_STATE(testrl, TESTRL_INTERVAL, 3);
+
+#define test_ratelimited(test, expected) \
+	KUNIT_ASSERT_EQ(test, ___ratelimit(&testrl, "test_ratelimit_smoke"), (expected))
+
+static void test_ratelimit_smoke(struct kunit *test)
+{
+	// Check settings.
+	KUNIT_ASSERT_GE(test, TESTRL_INTERVAL, 100);
+
+	// Test normal operation.
+	test_ratelimited(test, true);
+	test_ratelimited(test, true);
+	test_ratelimited(test, true);
+	test_ratelimited(test, false);
+
+	schedule_timeout_idle(TESTRL_INTERVAL / 2);
+	test_ratelimited(test, false);
+
+	schedule_timeout_idle(TESTRL_INTERVAL * 3 / 4);
+	test_ratelimited(test, true);
+
+	schedule_timeout_idle(2 * TESTRL_INTERVAL);
+	test_ratelimited(test, true);
+	test_ratelimited(test, true);
+
+	schedule_timeout_idle(TESTRL_INTERVAL / 2 );
+	test_ratelimited(test, true);
+	schedule_timeout_idle(TESTRL_INTERVAL * 3 / 4);
+	test_ratelimited(test, true);
+	test_ratelimited(test, true);
+	test_ratelimited(test, true);
+	test_ratelimited(test, false);
+
+	// Test disabling.
+	testrl.burst = 0;
+	test_ratelimited(test, false);
+	testrl.burst = 2;
+	testrl.interval = 0;
+	test_ratelimited(test, true);
+	test_ratelimited(test, true);
+	test_ratelimited(test, true);
+	test_ratelimited(test, true);
+	test_ratelimited(test, true);
+	test_ratelimited(test, true);
+	test_ratelimited(test, true);
+
+	// Testing re-enabling.
+	testrl.interval = TESTRL_INTERVAL;
+	test_ratelimited(test, true);
+	test_ratelimited(test, true);
+	test_ratelimited(test, false);
+	test_ratelimited(test, false);
+}
+
+static struct ratelimit_state stressrl = RATELIMIT_STATE_INIT_FLAGS("stressrl", HZ / 10, 3,
+								    RATELIMIT_MSG_ON_RELEASE);
+
+static const int stress_duration = 2 * HZ;
+
+struct stress_kthread {
+	unsigned long nattempts;
+	unsigned long nunlimited;
+	unsigned long nlimited;
+	unsigned long nmissed;
+	struct task_struct *tp;
+};
+
+static int test_ratelimit_stress_child(void *arg)
+{
+	struct stress_kthread *sktp = arg;
+
+	set_user_nice(current, MAX_NICE);
+
+	while (!kthread_should_stop()) {
+		sktp->nattempts++;
+		if (___ratelimit(&stressrl, __func__))
+			sktp->nunlimited++;
+		else
+			sktp->nlimited++;
+		cond_resched();
+	}
+
+	sktp->nmissed = ratelimit_state_reset_miss(&stressrl);
+	return 0;
+}
+
+static void test_ratelimit_stress(struct kunit *test)
+{
+	int i;
+	const int n_stress_kthread = cpumask_weight(cpu_online_mask);
+	struct stress_kthread skt = { 0 };
+	struct stress_kthread *sktp = kzalloc_objs(*sktp, n_stress_kthread);
+	int n_started = 0;
+
+	KUNIT_ASSERT_NOT_NULL_MSG(test, sktp, "Memory allocation failure");
+	for (i = 0; i < n_stress_kthread; i++) {
+		sktp[i].tp = kthread_run(test_ratelimit_stress_child, &sktp[i], "%s/%i",
+					 "test_ratelimit_stress_child", i);
+		if (IS_ERR(sktp[i].tp)) {
+			KUNIT_FAIL(test, "kthread_run failed: %ld", PTR_ERR(sktp[i].tp));
+			goto out_stop;
+		}
+		n_started++;
+		pr_alert("Spawned test_ratelimit_stress_child %d\n", i);
+	}
+	schedule_timeout_idle(stress_duration);
+
+out_stop:
+	for (i = 0; i < n_started; i++) {
+		kthread_stop(sktp[i].tp);
+		skt.nattempts += sktp[i].nattempts;
+		skt.nunlimited += sktp[i].nunlimited;
+		skt.nlimited += sktp[i].nlimited;
+		skt.nmissed += sktp[i].nmissed;
+	}
+	if (n_started == n_stress_kthread) {
+		KUNIT_ASSERT_EQ_MSG(test, skt.nunlimited + skt.nlimited, skt.nattempts,
+				    "Outcomes not equal to attempts");
+		KUNIT_ASSERT_EQ_MSG(test, skt.nlimited, skt.nmissed,
+				    "Misses not equal to limits");
+	}
+
+	kfree(sktp);
+}
+
+static struct kunit_case ratelimit_test_cases[] = {
+	KUNIT_CASE_SLOW(test_ratelimit_smoke),
+	KUNIT_CASE_SLOW(test_ratelimit_stress),
+	{}
+};
+
+static struct kunit_suite ratelimit_test_suite = {
+	.name = "lib_ratelimit",
+	.test_cases = ratelimit_test_cases,
+};
+
+kunit_test_suites(&ratelimit_test_suite);
+
+MODULE_DESCRIPTION("___ratelimit() KUnit test suite");
+MODULE_LICENSE("GPL");