linux-kernel - [PATCH] serial: core: Don't drop port_mutex in serial_core_remove_one

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Message-Id: <20230601105548.29965-1-steven.price@arm.com>
Date:   Thu,  1 Jun 2023 11:55:48 +0100
From:   Steven Price <steven.price@....com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        Tony Lindgren <tony@...mide.com>
Cc:     linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        linux-omap@...r.kernel.org, Vignesh Raghavendra <vigneshr@...com>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Johan Hovold <johan@...nel.org>,
        John Ogness <john.ogness@...utronix.de>,
        Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
        Dhruva Gole <d-gole@...com>,
        Steven Price <steven.price@....com>
Subject: [PATCH] serial: core: Don't drop port_mutex in serial_core_remove_one_port

Commit 84a9582fd203 ("serial: core: Start managing serial controllers to
enable runtime PM") required the caller to hold port_mutex rather than
taking it locally. However the mutex_unlock() call wasn't removed
causing the mutex to be dropped unexpectly. Remove the call to
mutex_unlock() (and fix up the early return) to restore correct
behaviour.

Fixes: 84a9582fd203 ("serial: core: Start managing serial controllers to enable runtime PM")
Signed-off-by: Steven Price <steven.price@....com>
---
 drivers/tty/serial/serial_core.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 29bd5ede0b25..efda90215ee9 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -3194,7 +3194,7 @@ static void serial_core_remove_one_port(struct uart_driver *drv,
 
 	if (!uart_port) {
 		mutex_unlock(&port->mutex);
-		goto out;
+		return;
 	}
 	mutex_unlock(&port->mutex);
 
@@ -3234,8 +3234,6 @@ static void serial_core_remove_one_port(struct uart_driver *drv,
 	wait_event(state->remove_wait, !atomic_read(&state->refcount));
 	state->uart_port = NULL;
 	mutex_unlock(&port->mutex);
-out:
-	mutex_unlock(&port_mutex);
 }
 
 /**
-- 
2.39.2