HID: multitouch: Add memory barriers

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

diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
index 2e72922e36f56524cac964ce697e2fef31793d2d..91a4d3fc30e0802a7e85acc94dbab98ef1d4f753 100644 (file)
--- 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)