HID: stop exporting hid_snto32()

[ Upstream commit c653ffc283404a6c1c0e65143a833180c7ff799b ]

The only user of hid_snto32() is Logitech HID++ driver, which always
calls hid_snto32() with valid size (constant, either 12 or 8) and
therefore can simply use sign_extend32().

Make the switch and remove hid_snto32(). Move snto32() and s32ton() to
avoid introducing forward declaration.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Link: https://patch.msgid.link/20241003144656.3786064-2-dmitry.torokhov@gmail.com
[bentiss: fix checkpatch warning]
Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
Stable-dep-of: a6b87bfc2ab5 ("HID: core: Harden s32ton() against conversion to 0 bits")
Signed-off-by: Sasha Levin <sashal@kernel.org>

3 files changed, 32 insertions, 38 deletions

diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 1a8e88624acf..5169d8d56c88 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -46,6 +46,34 @@ module_param_named(ignore_special_drivers, hid_ignore_special_drivers, int, 0600
 MODULE_PARM_DESC(ignore_special_drivers, "Ignore any special drivers and handle all devices by generic driver");
 
 /*
+ * Convert a signed n-bit integer to signed 32-bit integer.
+ */
+
+static s32 snto32(__u32 value, unsigned int n)
+{
+	if (!value || !n)
+		return 0;
+
+	if (n > 32)
+		n = 32;
+
+	return sign_extend32(value, n - 1);
+}
+
+/*
+ * Convert a signed 32-bit integer to a signed n-bit integer.
+ */
+
+static u32 s32ton(__s32 value, unsigned int n)
+{
+	s32 a = value >> (n - 1);
+
+	if (a && a != -1)
+		return value < 0 ? 1 << (n - 1) : (1 << (n - 1)) - 1;
+	return value & ((1 << n) - 1);
+}
+
+/*
  * Register a new report for a device.
  */
 
@@ -425,7 +453,7 @@ static int hid_parser_global(struct hid_parser *parser, struct hid_item *item)
 		 * both this and the standard encoding. */
 		raw_value = item_sdata(item);
 		if (!(raw_value & 0xfffffff0))
-			parser->global.unit_exponent = hid_snto32(raw_value, 4);
+			parser->global.unit_exponent = snto32(raw_value, 4);
 		else
 			parser->global.unit_exponent = raw_value;
 		return 0;
@@ -1318,39 +1346,6 @@ alloc_err:
 EXPORT_SYMBOL_GPL(hid_open_report);
 
 /*
- * Convert a signed n-bit integer to signed 32-bit integer.
- */
-
-static s32 snto32(__u32 value, unsigned n)
-{
-	if (!value || !n)
-		return 0;
-
-	if (n > 32)
-		n = 32;
-
-	return sign_extend32(value, n - 1);
-}
-
-s32 hid_snto32(__u32 value, unsigned n)
-{
-	return snto32(value, n);
-}
-EXPORT_SYMBOL_GPL(hid_snto32);
-
-/*
- * Convert a signed 32-bit integer to a signed n-bit integer.
- */
-
-static u32 s32ton(__s32 value, unsigned n)
-{
-	s32 a = value >> (n - 1);
-	if (a && a != -1)
-		return value < 0 ? 1 << (n - 1) : (1 << (n - 1)) - 1;
-	return value & ((1 << n) - 1);
-}
-
-/*
  * Extract/implement a data field from/to a little endian report (bit array).
  *
  * Code sort-of follows HID spec:
diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-logitech-hidpp.c
index 234ddd4422d9..59f630962338 100644
--- a/drivers/hid/hid-logitech-hidpp.c
+++ b/drivers/hid/hid-logitech-hidpp.c
@@ -3296,13 +3296,13 @@ static int m560_raw_event(struct hid_device *hdev, u8 *data, int size)
 					 120);
 		}
 
-		v = hid_snto32(hid_field_extract(hdev, data+3, 0, 12), 12);
+		v = sign_extend32(hid_field_extract(hdev, data + 3, 0, 12), 11);
 		input_report_rel(hidpp->input, REL_X, v);
 
-		v = hid_snto32(hid_field_extract(hdev, data+3, 12, 12), 12);
+		v = sign_extend32(hid_field_extract(hdev, data + 3, 12, 12), 11);
 		input_report_rel(hidpp->input, REL_Y, v);
 
-		v = hid_snto32(data[6], 8);
+		v = sign_extend32(data[6], 7);
 		if (v != 0)
 			hidpp_scroll_counter_handle_scroll(hidpp->input,
 					&hidpp->vertical_wheel_counter, v);
diff --git a/include/linux/hid.h b/include/linux/hid.h
index 017d31f1d27b..7d8d09318fa9 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -978,7 +978,6 @@ const struct hid_device_id *hid_match_device(struct hid_device *hdev,
 					     struct hid_driver *hdrv);
 bool hid_compare_device_paths(struct hid_device *hdev_a,
 			      struct hid_device *hdev_b, char separator);
-s32 hid_snto32(__u32 value, unsigned n);
 __u32 hid_field_extract(const struct hid_device *hid, __u8 *report,
 		     unsigned offset, unsigned n);