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Message-Id: <20201019101109.903651690@linutronix.de>
Date: Mon, 19 Oct 2020 12:06:32 +0200
From: Thomas Gleixner <tglx@...utronix.de>
To: LKML <linux-kernel@...r.kernel.org>
Cc: Peter Zijlstra <peterz@...radead.org>,
Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
Johan Hovold <johan@...nel.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
linux-usb@...r.kernel.org,
Thomas Winischhofer <thomas@...ischhofer.net>,
"Ahmed S. Darwish" <a.darwish@...utronix.de>,
Mathias Nyman <mathias.nyman@...el.com>,
Valentina Manea <valentina.manea.m@...il.com>,
Shuah Khan <shuah@...nel.org>,
Alan Stern <stern@...land.harvard.edu>,
linux-omap@...r.kernel.org, Kukjin Kim <kgene@...nel.org>,
Krzysztof Kozlowski <krzk@...nel.org>,
linux-arm-kernel@...ts.infradead.org,
linux-samsung-soc@...r.kernel.org, Felipe Balbi <balbi@...nel.org>,
Duncan Sands <duncan.sands@...e.fr>
Subject: [patch V2 03/13] USB: serial: keyspan_pda: Consolidate room query
From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Having two copies of the same code doesn't make the code more readable and
allocating a buffer of 1 byte for a synchronous operation is a pointless
exercise.
Allocate a byte buffer at init which can be used instead. The buffer is
only used in open() and tty->write(). Console writes are not calling into
the query. open() obviously happens before write() and the writes are
serialized by bit 0 of port->write_urbs_free which protects also the
transaction itself.
Move the actual query into a helper function and cleanup the usage sites in
keyspan_pda_write() and keyspan_pda_open().
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Cc: Johan Hovold <johan@...nel.org>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: linux-usb@...r.kernel.org
---
V2; Allocate a real buffer (Alan)
---
drivers/usb/serial/keyspan_pda.c | 108 +++++++++++++++++----------------------
1 file changed, 49 insertions(+), 59 deletions(-)
--- a/drivers/usb/serial/keyspan_pda.c
+++ b/drivers/usb/serial/keyspan_pda.c
@@ -47,6 +47,7 @@ struct keyspan_pda_private {
struct work_struct unthrottle_work;
struct usb_serial *serial;
struct usb_serial_port *port;
+ u8 *query_buf;
};
@@ -436,6 +437,31 @@ static int keyspan_pda_tiocmset(struct t
return rc;
}
+/*
+ * Using priv->query_buf is safe here because this is only called for TTY
+ * operations open() and write(). write() comes post open() obviously and
+ * write() itself is serialized via bit 0 of port->write_urbs_free. Console
+ * writes are never calling into this.
+ */
+static int keyspan_pda_query_room(struct usb_serial *serial,
+ struct keyspan_pda_private *priv)
+{
+ int res;
+
+ res = usb_control_msg(serial->dev, usb_rcvctrlpipe(serial->dev, 0),
+ 6, /* write_room */
+ USB_TYPE_VENDOR | USB_RECIP_INTERFACE | USB_DIR_IN,
+ 0, /* value */
+ 0, /* index */
+ priv->query_buf,
+ 1,
+ 2000);
+ if (res != 1)
+ return res < 0 ? res : -EIO;
+
+ return (unsigned int)*priv->query_buf;
+}
+
static int keyspan_pda_write(struct tty_struct *tty,
struct usb_serial_port *port, const unsigned char *buf, int count)
{
@@ -483,39 +509,16 @@ static int keyspan_pda_write(struct tty_
* usage because the console write can't sleep.
*/
if (count > priv->tx_room && tty) {
- u8 *room;
-
- room = kmalloc(1, GFP_KERNEL);
- if (!room) {
- rc = -ENOMEM;
- goto exit;
- }
-
- rc = usb_control_msg(serial->dev,
- usb_rcvctrlpipe(serial->dev, 0),
- 6, /* write_room */
- USB_TYPE_VENDOR | USB_RECIP_INTERFACE
- | USB_DIR_IN,
- 0, /* value: 0 means "remaining room" */
- 0, /* index */
- room,
- 1,
- 2000);
- if (rc > 0) {
- dev_dbg(&port->dev, "roomquery says %d\n", *room);
- priv->tx_room = *room;
- }
- kfree(room);
+ rc = keyspan_pda_query_room(serial, priv);
if (rc < 0) {
- dev_dbg(&port->dev, "roomquery failed\n");
- goto exit;
- }
- if (rc == 0) {
- dev_dbg(&port->dev, "roomquery returned 0 bytes\n");
- rc = -EIO; /* device didn't return any data */
+ dev_dbg(&port->dev, "roomquery failed %d\n", rc);
goto exit;
}
+
+ dev_dbg(&port->dev, "roomquery says %d\n", rc);
+ priv->tx_room = rc;
}
+
if (count > priv->tx_room) {
/* we're about to completely fill the Tx buffer, so
we'll be throttled afterwards. */
@@ -615,45 +618,26 @@ static int keyspan_pda_open(struct tty_s
struct usb_serial_port *port)
{
struct usb_serial *serial = port->serial;
- u8 *room;
- int rc = 0;
struct keyspan_pda_private *priv;
+ int rc;
- /* find out how much room is in the Tx ring */
- room = kmalloc(1, GFP_KERNEL);
- if (!room)
- return -ENOMEM;
+ priv = usb_get_serial_port_data(port);
- rc = usb_control_msg(serial->dev, usb_rcvctrlpipe(serial->dev, 0),
- 6, /* write_room */
- USB_TYPE_VENDOR | USB_RECIP_INTERFACE
- | USB_DIR_IN,
- 0, /* value */
- 0, /* index */
- room,
- 1,
- 2000);
+ /* find out how much room is in the Tx ring */
+ rc = keyspan_pda_query_room(serial, priv);
if (rc < 0) {
- dev_dbg(&port->dev, "%s - roomquery failed\n", __func__);
- goto error;
- }
- if (rc == 0) {
- dev_dbg(&port->dev, "%s - roomquery returned 0 bytes\n", __func__);
- rc = -EIO;
- goto error;
+ dev_dbg(&port->dev, "roomquery failed %d\n", rc);
+ return rc;
}
- priv = usb_get_serial_port_data(port);
- priv->tx_room = *room;
- priv->tx_throttled = *room ? 0 : 1;
+
+ priv->tx_room = rc;
+ priv->tx_throttled = rc ? 0 : 1;
/*Start reading from the device*/
rc = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
- if (rc) {
+ if (rc)
dev_dbg(&port->dev, "%s - usb_submit_urb(read int) failed\n", __func__);
- goto error;
- }
-error:
- kfree(room);
+
return rc;
}
static void keyspan_pda_close(struct usb_serial_port *port)
@@ -715,6 +699,11 @@ static int keyspan_pda_port_probe(struct
priv = kmalloc(sizeof(struct keyspan_pda_private), GFP_KERNEL);
if (!priv)
return -ENOMEM;
+ priv->query_buf = kmalloc(1, GFP_KERNEL);
+ if (!priv->query_buf) {
+ kfree(priv);
+ return -ENOMEM;
+ }
INIT_WORK(&priv->wakeup_work, keyspan_pda_wakeup_write);
INIT_WORK(&priv->unthrottle_work, keyspan_pda_request_unthrottle);
@@ -731,6 +720,7 @@ static int keyspan_pda_port_remove(struc
struct keyspan_pda_private *priv;
priv = usb_get_serial_port_data(port);
+ kfree(priv->query_buf);
kfree(priv);
return 0;
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