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, 218 insertions, 0 deletions

diff --git a/lib/find_bit_benchmark.c b/lib/find_bit_benchmark.c
new file mode 100644
index 000000000..05305e655
--- /dev/null
+++ b/lib/find_bit_benchmark.c
@@ -0,0 +1,218 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Test for find_*_bit functions.
+ *
+ * Copyright (c) 2017 Cavium.
+ */
+
+/*
+ * find_bit functions are widely used in kernel, so the successful boot
+ * is good enough test for correctness.
+ *
+ * This test is focused on performance of traversing bitmaps. Two typical
+ * scenarios are reproduced:
+ * - randomly filled bitmap with approximately equal number of set and
+ *   cleared bits;
+ * - sparse bitmap with few set bits at random positions.
+ */
+
+#include <linux/bitops.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/printk.h>
+#include <linux/random.h>
+
+#define BITMAP_LEN	(4096UL * 8 * 10)
+#define SPARSE		500
+
+static DECLARE_BITMAP(bitmap, BITMAP_LEN) __initdata;
+static DECLARE_BITMAP(bitmap2, BITMAP_LEN) __initdata;
+
+/*
+ * This is Schlemiel the Painter's algorithm.
+ */
+static int __init test_find_first_bit(const void *bitmap, unsigned long len)
+{
+	static DECLARE_BITMAP(cp, BITMAP_LEN) __initdata;
+	unsigned long i, cnt;
+	ktime_t time;
+
+	bitmap_copy(cp, bitmap, BITMAP_LEN);
+
+	time = ktime_get();
+	for (cnt = i = 0; i < len; cnt++) {
+		i = find_first_bit(cp, len);
+		__clear_bit(i, cp);
+	}
+	time = ktime_get() - time;
+	pr_err("find_first_bit:     %18llu ns, %6ld iterations\n", time, cnt);
+
+	return 0;
+}
+
+static int __init test_find_first_and_bit(const void *bitmap, const void *bitmap2,
+		unsigned long len)
+{
+	static DECLARE_BITMAP(cp, BITMAP_LEN) __initdata;
+	unsigned long i, cnt;
+	ktime_t time;
+
+	bitmap_copy(cp, bitmap, BITMAP_LEN);
+
+	time = ktime_get();
+	for (cnt = i = 0; i < len; cnt++) {
+		i = find_first_and_bit(cp, bitmap2, len);
+		__clear_bit(i, cp);
+	}
+	time = ktime_get() - time;
+	pr_err("find_first_and_bit: %18llu ns, %6ld iterations\n", time, cnt);
+
+	return 0;
+}
+
+static int __init test_find_next_bit(const void *bitmap, unsigned long len)
+{
+	unsigned long i, cnt;
+	ktime_t time;
+
+	time = ktime_get();
+	for (cnt = i = 0; i < BITMAP_LEN; cnt++)
+		i = find_next_bit(bitmap, BITMAP_LEN, i) + 1;
+	time = ktime_get() - time;
+	pr_err("find_next_bit:      %18llu ns, %6ld iterations\n", time, cnt);
+
+	return 0;
+}
+
+static int __init test_find_next_zero_bit(const void *bitmap, unsigned long len)
+{
+	unsigned long i, cnt;
+	ktime_t time;
+
+	time = ktime_get();
+	for (cnt = i = 0; i < BITMAP_LEN; cnt++)
+		i = find_next_zero_bit(bitmap, len, i) + 1;
+	time = ktime_get() - time;
+	pr_err("find_next_zero_bit: %18llu ns, %6ld iterations\n", time, cnt);
+
+	return 0;
+}
+
+static int __init test_find_last_bit(const void *bitmap, unsigned long len)
+{
+	unsigned long l, cnt = 0;
+	ktime_t time;
+
+	time = ktime_get();
+	do {
+		cnt++;
+		l = find_last_bit(bitmap, len);
+		if (l >= len)
+			break;
+		len = l;
+	} while (len);
+	time = ktime_get() - time;
+	pr_err("find_last_bit:      %18llu ns, %6ld iterations\n", time, cnt);
+
+	return 0;
+}
+
+static int __init test_find_nth_bit(const unsigned long *bitmap, unsigned long len)
+{
+	unsigned long l, n, w = bitmap_weight(bitmap, len);
+	ktime_t time;
+
+	time = ktime_get();
+	for (n = 0; n < w; n++) {
+		l = find_nth_bit(bitmap, len, n);
+		WARN_ON(l >= len);
+	}
+	time = ktime_get() - time;
+	pr_err("find_nth_bit:       %18llu ns, %6ld iterations\n", time, w);
+
+	return 0;
+}
+
+static int __init test_find_next_and_bit(const void *bitmap,
+		const void *bitmap2, unsigned long len)
+{
+	unsigned long i, cnt;
+	ktime_t time;
+
+	time = ktime_get();
+	for (cnt = i = 0; i < BITMAP_LEN; cnt++)
+		i = find_next_and_bit(bitmap, bitmap2, BITMAP_LEN, i + 1);
+	time = ktime_get() - time;
+	pr_err("find_next_and_bit:  %18llu ns, %6ld iterations\n", time, cnt);
+
+	return 0;
+}
+
+static int __init
+test_bitmap_find_next_zero_area_off(unsigned long *bitmap, unsigned long len)
+{
+	unsigned long i, cnt;
+	ktime_t time;
+
+	time = ktime_get();
+	for (cnt = i = 0; i < BITMAP_LEN; cnt++)
+		i = bitmap_find_next_zero_area_off(bitmap, BITMAP_LEN, i, 8, 0, 0) + 1;
+	time = ktime_get() - time;
+	pr_err("bitmap_find_next_zero_area_off:%7llu ns, %6ld iterations\n", time, cnt);
+
+	return 0;
+}
+
+static int __init find_bit_test(void)
+{
+	unsigned long nbits = BITMAP_LEN / SPARSE;
+
+	pr_err("\nStart testing find_bit() with random-filled bitmap\n");
+
+	get_random_bytes(bitmap, sizeof(bitmap));
+	get_random_bytes(bitmap2, sizeof(bitmap2));
+
+	test_bitmap_find_next_zero_area_off(bitmap, BITMAP_LEN);
+	test_find_next_bit(bitmap, BITMAP_LEN);
+	test_find_next_zero_bit(bitmap, BITMAP_LEN);
+	test_find_last_bit(bitmap, BITMAP_LEN);
+	test_find_nth_bit(bitmap, BITMAP_LEN / 10);
+
+	/*
+	 * test_find_first_bit() may take some time, so
+	 * traverse only part of bitmap to avoid soft lockup.
+	 */
+	test_find_first_bit(bitmap, BITMAP_LEN / 10);
+	test_find_first_and_bit(bitmap, bitmap2, BITMAP_LEN / 2);
+	test_find_next_and_bit(bitmap, bitmap2, BITMAP_LEN);
+
+	pr_err("\nStart testing find_bit() with sparse bitmap\n");
+
+	bitmap_zero(bitmap, BITMAP_LEN);
+	bitmap_zero(bitmap2, BITMAP_LEN);
+
+	while (nbits--) {
+		__set_bit(get_random_u32_below(BITMAP_LEN), bitmap);
+		__set_bit(get_random_u32_below(BITMAP_LEN), bitmap2);
+	}
+
+	test_bitmap_find_next_zero_area_off(bitmap, BITMAP_LEN);
+	test_find_next_bit(bitmap, BITMAP_LEN);
+	test_find_next_zero_bit(bitmap, BITMAP_LEN);
+	test_find_last_bit(bitmap, BITMAP_LEN);
+	test_find_nth_bit(bitmap, BITMAP_LEN);
+	test_find_first_bit(bitmap, BITMAP_LEN);
+	test_find_first_and_bit(bitmap, bitmap2, BITMAP_LEN);
+	test_find_next_and_bit(bitmap, bitmap2, BITMAP_LEN);
+
+	/*
+	 * Everything is OK. Return error just to let user run benchmark
+	 * again without annoying rmmod.
+	 */
+	return -EINVAL;
+}
+module_init(find_bit_test);
+
+MODULE_DESCRIPTION("Test for find_*_bit functions");
+MODULE_LICENSE("GPL");