This is definitely (still) upstream in tp_detect_thumb_while_moving().
I have 1.12.0-1, identical to HEAD evdev-mt-touchpad.c as of right now.
The assumption that there is one (or more) new TOUCH_BEGIN touch and one
(or more) older TOUCH_UPDATE (not _BEGIN or _HOVER or _NONE) touch is false.
Here are two touches that triggered this bug for me, extracted from a core:
{ tp = 0x55952647f5e0,
index = 0,
state = TOUCH_BEGIN,
has_ended = false,
dirty = true,
point = { x = 167, y = 3432 },
time = 29468145253,
pressure = 0,
is_tool_palm = false,
major = 152,
minor = 264,
was_down = true,
quirks = { reset_motion_history = true },
history = { samples = { { time = 29468121253,
point = { x = 113, y = 3477 } },
{ time = 29468129254,
point = { x = 115, y = 3475 } },
{ time = 29468137199,
point = { x = 129, y = 3460 } },
{ time = 29468145253,
point = { x = 167, y = 3432 } } },
index = 3,
count = 1 },
jumps = { last_delta_mm = 0 },
hysteresis = { center = { x = 167, y = 3432 },
x_motion_history = 0 '\000' },
pinned = { is_pinned = false, center = { x = 2818, y = 2976 } },
button = { state = BUTTON_STATE_NONE,
current = 0,
timer = { libinput = 0x5595264688d0,
timer_name = 0x55952647f2e0 "event12 (1) button",
link = { prev = 0x0, next = 0x0 },
expire = 0,
timer_func =
0x7f8624ec3450 < tp_button_handle_timeout >,
timer_func_data = 0x55952647fba0 },
initial = { x = 1647, y = 4150 },
has_moved = false },
tap = { state = TAP_TOUCH_STATE_IDLE,
initial = { x = 1647, y = 4150 },
is_thumb = false,
is_palm = false },
scroll = { edge_state = EDGE_SCROLL_TOUCH_STATE_NONE,
edge = 0,
direction = -1,
timer = { libinput = 0x5595264688d0,
timer_name = 0x559526481950 "event12 (0)
edgescroll",
link = { prev = 0x0, next = 0x0 },
expire = 0,
timer_func =
0x7f8624ec4f70 < tp_edge_scroll_handle_timeout >,
timer_func_data = 0x55952647fba0 },
initial = { x = 0, y = 0 } },
palm = { state = PALM_NONE,
first = { x = 5023, y = 4326 },
time = 29468145253 },
gesture = { initial = { x = 1629, y = 4030 } },
thumb = { state = THUMB_STATE_NO,
first_touch_time = 29468145253,
initial = { x = -205, y = 5762 } },
speed = { last_speed = 27.794631398589125, exceeded_count = 1 } },
and
{ tp = 0x55952647f5e0,
index = 1,
state = TOUCH_BEGIN,
has_ended = false,
dirty = true,
point = { x = 1456, y = 2133 },
time = 29468145253,
pressure = 0,
is_tool_palm = false,
major = 135,
minor = 203,
was_down = true,
quirks = { reset_motion_history = true },
history = { samples = { { time = 29468121253,
point = { x = 1472, y = 2252 } },
{ time = 29468129254,
point = { x = 1460, y = 2206 } },
{ time = 29468137199,
point = { x = 1451, y = 2173 } },
{ time = 29468145253,
point = { x = 1456, y = 2133 } } },
index = 3,
count = 1 },
jumps = { last_delta_mm = 0 },
hysteresis = { center = { x = 1456, y = 2133 },
x_motion_history = 0 '\000' },
pinned = { is_pinned = false, center = { x = 1740, y = 3448 } },
button = { state = BUTTON_STATE_NONE,
current = 0,
timer = { libinput = 0x5595264688d0,
timer_name = 0x55952647f4c0 "event12 (2) button",
link = { prev = 0x0, next = 0x0 },
expire = 0,
timer_func =
0x7f8624ec3450 < tp_button_handle_timeout >,
timer_func_data = 0x55952647fd40 },
initial = { x = 243, y = 5311 },
has_moved = false },
tap = { state = TAP_TOUCH_STATE_IDLE,
initial = { x = 243, y = 5311 },
is_thumb = false,
is_palm = false },
scroll = { edge_state = EDGE_SCROLL_TOUCH_STATE_NONE,
edge = 0,
direction = -1,
timer = { libinput = 0x5595264688d0,
timer_name = 0x559526481970 "event12 (0)
edgescroll",
link = { prev = 0x0, next = 0x0 },
expire = 0,
timer_func =
0x7f8624ec4f70 < tp_edge_scroll_handle_timeout
>,
timer_func_data = 0x55952647fd40 },
initial = { x = 0, y = 0 } },
palm = { state = PALM_NONE,
first = { x = 5044, y = 5262 },
time = 29468145253 },
gesture = { initial = { x = 239, y = 5243 } },
thumb = { state = THUMB_STATE_NO,
first_touch_time = 29468145253,
initial = { x = 1700, y = 6327 } },
speed = { last_speed = 46.728018982837312, exceeded_count = 9 } },
the rest were _NONEs
