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

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Date:	Wed, 20 Feb 2008 20:45:58 +0000
From:	Alan Cox <alan@...rguk.ukuu.org.uk>
To:	akpm@...l.org, linux-kernel@...r.kernel.org
Subject: [PATCH] serial_core: Prepare for BKL push down

Instead of checking for the BKL in these methods, take it ourselves. That
avoids propogating it into the serial drivers and we can then fix them
later on.

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/serial/serial_core.c linux-2.6.25-rc2-mm1/drivers/serial/serial_core.c
--- linux.vanilla-2.6.25-rc2-mm1/drivers/serial/serial_core.c	2008-02-19 11:03:01.000000000 +0000
+++ linux-2.6.25-rc2-mm1/drivers/serial/serial_core.c	2008-02-20 16:22:49.000000000 +0000
@@ -907,14 +914,14 @@
 	struct uart_state *state = tty->driver_data;
 	struct uart_port *port = state->port;
 
-	BUG_ON(!kernel_locked());
-
+	lock_kernel();
 	mutex_lock(&state->mutex);
 
 	if (port->type != PORT_UNKNOWN)
 		port->ops->break_ctl(port, break_state);
 
 	mutex_unlock(&state->mutex);
+	unlock_kernel();
 }
 
 static int uart_do_autoconfig(struct uart_state *state)
@@ -1052,7 +1059,7 @@
 }
 
 /*
- * Called via sys_ioctl under the BKL.  We can use spin_lock_irq() here.
+ * Called via sys_ioctl.  We can use spin_lock_irq() here.
  */
 static int
 uart_ioctl(struct tty_struct *tty, struct file *filp, unsigned int cmd,
@@ -1062,8 +1069,8 @@
 	void __user *uarg = (void __user *)arg;
 	int ret = -ENOIOCTLCMD;
 
-	BUG_ON(!kernel_locked());
 
+	lock_kernel();
 	/*
 	 * These ioctls don't rely on the hardware to be present.
 	 */
@@ -1136,6 +1143,7 @@
  out_up:
 	mutex_unlock(&state->mutex);
  out:
+	unlock_kernel();
 	return ret;
 }
 
@@ -1146,7 +1154,6 @@
 	unsigned long flags;
 	unsigned int cflag = tty->termios->c_cflag;
 
-	BUG_ON(!kernel_locked());
 
 	/*
 	 * These are the bits that are used to setup various
@@ -1158,9 +1165,11 @@
 	if ((cflag ^ old_termios->c_cflag) == 0 &&
 	    tty->termios->c_ospeed == old_termios->c_ospeed &&
 	    tty->termios->c_ispeed == old_termios->c_ispeed &&
-	    RELEVANT_IFLAG(tty->termios->c_iflag ^ old_termios->c_iflag) == 0)
+	    RELEVANT_IFLAG(tty->termios->c_iflag ^ old_termios->c_iflag) == 0) {
 		return;
+	}
 
+	lock_kernel();
 	uart_change_speed(state, old_termios);
 
 	/* Handle transition to B0 status */
@@ -1193,7 +1202,7 @@
 		}
 		spin_unlock_irqrestore(&state->port->lock, flags);
 	}
-
+	unlock_kernel();
 #if 0
 	/*
 	 * No need to wake up processes in open wait, since they
--
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