Hello Benjamin Tissoires,
This is a semi-automatic email about new static checker warnings.
The patch e2c7d8877e5c: "HID: wacom: check for wacom->shared before
following the pointer" from Mar 5, 2015, leads to the following
Smatch complaint:
drivers/hid/wacom_wac.c:602 wacom_intuos_inout()
error: we previously assumed 'wacom->shared' could be null (see line 584)
drivers/hid/wacom_wac.c
583
584 if (wacom->shared) {
In the original code we checked "if (features->quirks & WACOM_QUIRK_MULTI_INPUT)"
which is ensures that "wacom->shared" is non-NULL.
585 wacom->shared->stylus_in_proximity = true;
586
587 if (wacom->shared->touch_down)
588 return 1;
589 }
590
591 /* in Range while exiting */
592 if (((data[1] & 0xfe) == 0x20) && wacom->reporting_data) {
593 input_report_key(input, BTN_TOUCH, 0);
594 input_report_abs(input, ABS_PRESSURE, 0);
595 input_report_abs(input, ABS_DISTANCE, wacom->features.distance_max);
596 return 2;
597 }
598
599 /* Exit report */
600 if ((data[1] & 0xfe) == 0x80) {
601 if (features->quirks & WACOM_QUIRK_MULTI_INPUT)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
We still check for that here. Smatch is confused.
602 wacom->shared->stylus_in_proximity = false;
^^^^^^^^^^^^^
This is not a bug, but change the previous change to
"if (wacom->shared)" would make the code more consistent.
603 wacom->reporting_data = false;
604
[ snip ]
1072 static int wacom_24hdt_irq(struct wacom_wac *wacom)
1073 {
1074 struct input_dev *input = wacom->input;
1075 unsigned char *data = wacom->data;
1076 int i;
1077 int current_num_contacts = data[61];
1078 int contacts_to_send = 0;
1079 int num_contacts_left = 4; /* maximum contacts per packet */
1080 int byte_per_packet = WACOM_BYTES_PER_24HDT_PACKET;
1081 int y_offset = 2;
1082 static int contact_with_no_pen_down_count = 0;
1083
1084 if (wacom->features.type == WACOM_27QHDT) {
1085 current_num_contacts = data[63];
1086 num_contacts_left = 10;
1087 byte_per_packet = WACOM_BYTES_PER_QHDTHID_PACKET;
1088 y_offset = 0;
1089 }
1090
1091 /*
1092 * First packet resets the counter since only the first
1093 * packet in series will have non-zero current_num_contacts.
1094 */
1095 if (current_num_contacts) {
1096 wacom->num_contacts_left = current_num_contacts;
1097 contact_with_no_pen_down_count = 0;
1098 }
1099
1100 contacts_to_send = min(num_contacts_left, wacom->num_contacts_left);
1101
1102 for (i = 0; i < contacts_to_send; i++) {
1103 int offset = (byte_per_packet * i) + 1;
1104 bool touch = (data[offset] & 0x1) && !wacom->shared->stylus_in_proximity;
^^^^^^^^^^^^^
I assume this hardware is always quirky so this won't cause a NULL
deref?
1105 int slot = input_mt_get_slot_by_key(input, data[offset + 1]);
1106
1107 if (slot < 0)
1108 continue;
regards,
dan carpenter
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