On Wed, Sep 7, 2022 at 5:02 PM Andri Yngvason <andri@xxxxxxxxxxx> wrote:
>
> 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@xxxxxxxxxxxxxxx
> Fixes: 9609827458c3 ("HID: multitouch: optimize the sticky fingers timer")
> Signed-off-by: Andri Yngvason <andri@xxxxxxxxxxx>
> ---
Applied to for-6.1/multitouch in hid.git
Sorry for the delay
Cheers,
Benjamin
> V1 -> V2: Clarified where the race is and added Fixes tag as suggested
> by Greg KH
> V2 -> V3: Fix formatting of "Fixes" tag
>
> drivers/hid/hid-multitouch.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
> index 2e72922e36f5..91a4d3fc30e0 100644
> --- a/drivers/hid/hid-multitouch.c
> +++ b/drivers/hid/hid-multitouch.c
> @@ -1186,7 +1186,7 @@ static void mt_touch_report(struct hid_device *hid,
> 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_device *hid,
> 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 timer_list *t)
> * 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)
> --
> 2.37.2
>
