linux-kernel - [PATCH 5.4 023/255] HID: multitouch: Add memory barriers

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Message-Id: <20221024113003.209473654@linuxfoundation.org>
Date:   Mon, 24 Oct 2022 13:28:53 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Andri Yngvason <andri@...vason.is>,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>
Subject: [PATCH 5.4 023/255] HID: multitouch: Add memory barriers

From: Andri Yngvason <andri@...vason.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@...r.kernel.org
Fixes: 9609827458c3 ("HID: multitouch: optimize the sticky fingers timer")
Signed-off-by: Andri Yngvason <andri@...vason.is>
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@...hat.com>
Link: https://lore.kernel.org/r/20220907150159.2285460-1-andri@yngvason.is
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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
@@ -1162,7 +1162,7 @@ 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;
@@ -1243,7 +1243,7 @@ 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,
@@ -1680,11 +1680,11 @@ 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)