[PATCH 5.19 040/717] HID: multitouch: Add memory barriers

Greg Kroah-Hartman
2022-10-22T07:38:01Z

From: Andri Yngvason <andri@yngvason.is>

commit be6e2b5734a425941fcdcdbd2a9337be498ce2cf upstream.

This fixes broken atomic checks which cause a race between the
release-timer and processing of hid input.

I noticed that contacts were sometimes sticking, even with the "sticky
fingers" quirk enabled. This fixes that problem.

Cc: stable@vger.kernel.org
Fixes: 9609827458c3 ("HID: multitouch: optimize the sticky fingers timer")
Signed-off-by: Andri Yngvason <andri@yngvason.is>
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Link: https://lore.kernel.org/r/20220907150159.2285460-1-andri@yngvason.is
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/hid/hid-multitouch.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

--- a/drivers/hid/hid-multitouch.c
+++ b/drivers/hid/hid-multitouch.c
@@ -1186,7 +1186,7 @@ static void mt_touch_report(struct hid_d
int contact_count = -1;

/* sticky fingers release in progress, abort */
- if (test_and_set_bit(MT_IO_FLAGS_RUNNING, &td->mt_io_flags))
+ if (test_and_set_bit_lock(MT_IO_FLAGS_RUNNING, &td->mt_io_flags))
return;

scantime = *app->scantime;
@@ -1267,7 +1267,7 @@ static void mt_touch_report(struct hid_d
del_timer(&td->release_timer);
}

- clear_bit(MT_IO_FLAGS_RUNNING, &td->mt_io_flags);
+ clear_bit_unlock(MT_IO_FLAGS_RUNNING, &td->mt_io_flags);
}

static int mt_touch_input_configured(struct hid_device *hdev,
@@ -1699,11 +1699,11 @@ static void mt_expired_timeout(struct ti
* An input report came in just before we release the sticky fingers,
* it will take care of the sticky fingers.
*/
- if (test_and_set_bit(MT_IO_FLAGS_RUNNING, &td->mt_io_flags))
+ if (test_and_set_bit_lock(MT_IO_FLAGS_RUNNING, &td->mt_io_flags))
return;
if (test_bit(MT_IO_FLAGS_PENDING_SLOTS, &td->mt_io_flags))
mt_release_contacts(hdev);
- clear_bit(MT_IO_FLAGS_RUNNING, &td->mt_io_flags);
+ clear_bit_unlock(MT_IO_FLAGS_RUNNING, &td->mt_io_flags);
}

static int mt_probe(struct hid_device *hdev, const struct hid_device_id *id)