linux-kernel - [PATCH 3/6] USB: serial: io_edgeport: drop buffer-callback sanity checks

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Date:   Wed, 19 May 2021 11:20:03 +0200
From:   Johan Hovold <johan@...nel.org>
To:     Johan Hovold <johan@...nel.org>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 3/6] USB: serial: io_edgeport: drop buffer-callback sanity checks

The driver write_room and chars_in_buffer callbacks used to incorrectly
return a negative errno in case they were called while or after the port
had been closed. The return value was later changed to zero by commit
d76f2f4462bb ("io_edgeport: Fix various bogus returns to the tty
layer") but the bogus sanity checks were left in place as were the
outdated function-header comments.

These callbacks will never be called for an uninitialised port so drop
the unnecessary sanity checks and the outdated comments.

Signed-off-by: Johan Hovold <johan@...nel.org>
---
 drivers/usb/serial/io_edgeport.c | 27 +--------------------------
 1 file changed, 1 insertion(+), 26 deletions(-)

diff --git a/drivers/usb/serial/io_edgeport.c b/drivers/usb/serial/io_edgeport.c
index 1f8dff4390c7..ea4edf5eed27 100644
--- a/drivers/usb/serial/io_edgeport.c
+++ b/drivers/usb/serial/io_edgeport.c
@@ -1351,9 +1351,7 @@ static void send_more_port_data(struct edgeport_serial *edge_serial,
 /*****************************************************************************
  * edge_write_room
  *	this function is called by the tty driver when it wants to know how
- *	many bytes of data we can accept for a specific port. If successful,
- *	we return the amount of room that we have for this port	(the txCredits)
- *	otherwise we return a negative error number.
+ *	many bytes of data we can accept for a specific port.
  *****************************************************************************/
 static unsigned int edge_write_room(struct tty_struct *tty)
 {
@@ -1362,16 +1360,6 @@ static unsigned int edge_write_room(struct tty_struct *tty)
 	unsigned int room;
 	unsigned long flags;
 
-	if (edge_port == NULL)
-		return 0;
-	if (edge_port->closePending)
-		return 0;
-
-	if (!edge_port->open) {
-		dev_dbg(&port->dev, "%s - port not opened\n", __func__);
-		return 0;
-	}
-
 	/* total of both buffers is still txCredit */
 	spin_lock_irqsave(&edge_port->ep_lock, flags);
 	room = edge_port->txCredits - edge_port->txfifo.count;
@@ -1387,9 +1375,6 @@ static unsigned int edge_write_room(struct tty_struct *tty)
  *	this function is called by the tty driver when it wants to know how
  *	many bytes of data we currently have outstanding in the port (data that
  *	has been written, but hasn't made it out the port yet)
- *	If successful, we return the number of bytes left to be written in the
- *	system,
- *	Otherwise we return a negative error number.
  *****************************************************************************/
 static unsigned int edge_chars_in_buffer(struct tty_struct *tty)
 {
@@ -1398,16 +1383,6 @@ static unsigned int edge_chars_in_buffer(struct tty_struct *tty)
 	unsigned int num_chars;
 	unsigned long flags;
 
-	if (edge_port == NULL)
-		return 0;
-	if (edge_port->closePending)
-		return 0;
-
-	if (!edge_port->open) {
-		dev_dbg(&port->dev, "%s - port not opened\n", __func__);
-		return 0;
-	}
-
 	spin_lock_irqsave(&edge_port->ep_lock, flags);
 	num_chars = edge_port->maxTxCredits - edge_port->txCredits +
 						edge_port->txfifo.count;
-- 
2.26.3