linux-kernel - [PATCH 2/2] Input: i8042 - Lock i8042

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Message-Id: <20200827135205.2.I1417edfd3526143f14fea2546787ba4bb6f32ae8@changeid>
Date:   Thu, 27 Aug 2020 13:52:23 -0600
From:   Raul E Rangel <rrangel@...omium.org>
To:     linux-input@...r.kernel.org
Cc:     dmitry.torokhov@...il.com, Shirish.S@....com,
        Raul E Rangel <rrangel@...omium.org>,
        Rajat Jain <rajatja@...gle.com>,
        Stephen Boyd <swboyd@...omium.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] Input: i8042 - Lock i8042_mutex before flushing

Make i8042_flush lock the i8042_mutex before flushing the buffer. This
will prevent i8042_flush from clearing the buffer while a PS/2 command is
in progress. I'm not sure if this is really possible. We already
hold the lock when calling i8042_command, so this makes i8042_flush have
the same behavior.

Signed-off-by: Raul E Rangel <rrangel@...omium.org>
---

 drivers/input/serio/i8042.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/input/serio/i8042.c b/drivers/input/serio/i8042.c
index 8590e51bcc087..b693154641500 100644
--- a/drivers/input/serio/i8042.c
+++ b/drivers/input/serio/i8042.c
@@ -254,6 +254,8 @@ static int i8042_flush(void)
 	int count = 0;
 	int retval = 0;
 
+	mutex_lock(&i8042_mutex);
+
 	spin_lock_irqsave(&i8042_lock, flags);
 
 	while ((str = i8042_read_status()) & I8042_STR_OBF) {
@@ -270,6 +272,8 @@ static int i8042_flush(void)
 
 	spin_unlock_irqrestore(&i8042_lock, flags);
 
+	mutex_unlock(&i8042_mutex);
+
 	return retval;
 }
 
-- 
2.28.0.297.g1956fa8f8d-goog