HID: core: de-duplicate some code in hid_input_field()

I had to go twice through the history to get a grasp at this code.
De-duplicate the various tests in one common helper to make it
more explicit.

Note that the `HID_UP_KEYBOARD + 1` condition is tested through
https://gitlab.freedesktop.org/libevdev/hid-tools/-/merge_requests/121

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Reviewed-by: Ping Cheng <ping.cheng@wacom.com>
Acked-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 75e7b84..fad4dbd 100644 (file)
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -1526,6 +1526,24 @@ static void hid_process_event(struct hid_device *hid, struct hid_field *field,
 }
 
 /*
+ * Checks if the given value is valid within this field
+ */
+static inline int hid_array_value_is_valid(struct hid_field *field,
+                                          __s32 value)
+{
+       __s32 min = field->logical_minimum;
+
+       /*
+        * Value needs to be between logical min and max, and
+        * (value - min) is used as an index in the usage array.
+        * This array is of size field->maxusage
+        */
+       return value >= min &&
+              value <= field->logical_maximum &&
+              value - min < field->maxusage;
+}
+
+/*
  * Analyse a received field, and fetch the data from it. The field
  * content is stored for next report processing (we do differential
  * reporting to the layer).
@@ -1539,7 +1557,6 @@ static void hid_input_field(struct hid_device *hid, struct hid_field *field,
        unsigned offset = field->report_offset;
        unsigned size = field->report_size;
        __s32 min = field->logical_minimum;
-       __s32 max = field->logical_maximum;
        __s32 *value;
 
        value = field->new_value;
@@ -1554,8 +1571,7 @@ static void hid_input_field(struct hid_device *hid, struct hid_field *field,
 
                /* Ignore report if ErrorRollOver */
                if (!(field->flags & HID_MAIN_ITEM_VARIABLE) &&
-                   value[n] >= min && value[n] <= max &&
-                   value[n] - min < field->maxusage &&
+                   hid_array_value_is_valid(field, value[n]) &&
                    field->usage[value[n] - min].hid == HID_UP_KEYBOARD + 1)
                        return;
        }
@@ -1563,21 +1579,29 @@ static void hid_input_field(struct hid_device *hid, struct hid_field *field,
        for (n = 0; n < count; n++) {
 
                if (HID_MAIN_ITEM_VARIABLE & field->flags) {
-                       hid_process_event(hid, field, &field->usage[n], value[n], interrupt);
+                       hid_process_event(hid,
+                                         field,
+                                         &field->usage[n],
+                                         value[n],
+                                         interrupt);
                        continue;
                }
 
-               if (field->value[n] >= min && field->value[n] <= max
-                       && field->value[n] - min < field->maxusage
-                       && field->usage[field->value[n] - min].hid
-                       && search(value, field->value[n], count))
-                               hid_process_event(hid, field, &field->usage[field->value[n] - min], 0, interrupt);
-
-               if (value[n] >= min && value[n] <= max
-                       && value[n] - min < field->maxusage
-                       && field->usage[value[n] - min].hid
-                       && search(field->value, value[n], count))
-                               hid_process_event(hid, field, &field->usage[value[n] - min], 1, interrupt);
+               if (hid_array_value_is_valid(field, field->value[n]) &&
+                   search(value, field->value[n], count))
+                       hid_process_event(hid,
+                                         field,
+                                         &field->usage[field->value[n] - min],
+                                         0,
+                                         interrupt);
+
+               if (hid_array_value_is_valid(field, value[n]) &&
+                   search(field->value, value[n], count))
+                       hid_process_event(hid,
+                                         field,
+                                         &field->usage[value[n] - min],
+                                         1,
+                                         interrupt);
        }
 
        memcpy(field->value, value, count * sizeof(__s32));