linux-kernel - [PATCH] usb-serial: Prepare for BKL push down

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Date:	Wed, 20 Feb 2008 20:47:56 +0000
From:	Alan Cox <alan@...rguk.ukuu.org.uk>
To:	akpm@...l.org, linux-kernel@...r.kernel.org, greg@...ah.com
Subject: [PATCH] usb-serial: Prepare for BKL push down

Take the lock in usb-serial instead. As it relies on the BKL internally
we can't push it any deeper yet.

Signed-off-by: Alan Cox <alan@...hat.com>

diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.vanilla-2.6.25-rc2-mm1/drivers/usb/serial/usb-serial.c linux-2.6.25-rc2-mm1/drivers/usb/serial/usb-serial.c
--- linux.vanilla-2.6.25-rc2-mm1/drivers/usb/serial/usb-serial.c	2008-02-19 11:03:01.000000000 +0000
+++ linux-2.6.25-rc2-mm1/drivers/usb/serial/usb-serial.c	2008-02-20 11:53:06.000000000 +0000
@@ -401,11 +401,13 @@
 	struct usb_serial_port *port = tty->driver_data;
 	int retval = -ENODEV;
 
+	lock_kernel();
 	if (!port)
 		goto exit;
 
 	dbg("%s - port %d, cmd 0x%.4x", __FUNCTION__, port->number, cmd);
 
+	/* Caution - port->open_count is BKL protected */
 	if (!port->open_count) {
 		dbg ("%s - port not open", __FUNCTION__);
 		goto exit;
@@ -416,8 +418,8 @@
 		retval = port->serial->type->ioctl(port, file, cmd, arg);
 	else
 		retval = -ENOIOCTLCMD;
-
 exit:
+	unlock_kernel();
 	return retval;
 }
 
@@ -446,19 +448,24 @@
 {
 	struct usb_serial_port *port = tty->driver_data;
 
-	if (!port)
+	lock_kernel();
+	if (!port) {
+		unlock_kernel();
 		return;
+	}
 
 	dbg("%s - port %d", __FUNCTION__, port->number);
 
 	if (!port->open_count) {
 		dbg("%s - port not open", __FUNCTION__);
+		unlock_kernel();
 		return;
 	}
 
 	/* pass on to the driver specific version of this function if it is available */
 	if (port->serial->type->break_ctl)
 		port->serial->type->break_ctl(port, break_state);
+	unlock_kernel();
 }
 
 static int serial_read_proc (char *page, char **start, off_t off, int count, int *eof, void *data)
--
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