From 75c33ce64e9c56fb59b5984b3383d28e27c4ce23 Mon Sep 17 00:00:00 2001
From: Shaun Ruffell <sruffell@digium.com>
Date: Thu, 25 Nov 2010 00:07:10 +0000
Subject: [PATCH] dahdi: A little cleanup in the dahdi_ioctl_iomux function.

The primary change is to make clear that the wait result is not ever to
be returned by the function.  There are also edits to remove some
comments that were expressed clearly in the source already and ensure
that the iomux member of 'struct dahdi_chan' is only accessed under the
chan->lock.

Signed-off-by: Shaun Ruffell <sruffell@digium.com>
Signed-off-by: Sean Bright <sean.bright@gmail.com>

git-svn-id: http://svn.asterisk.org/svn/dahdi/linux/trunk@9497 a0bf4364-ded3-4de4-8d8a-66a801d63aff
---
 drivers/dahdi/dahdi-base.c | 58 ++++++++++++++++----------------------
 include/dahdi/kernel.h     |  2 +-
 2 files changed, 26 insertions(+), 34 deletions(-)

diff --git a/drivers/dahdi/dahdi-base.c b/drivers/dahdi/dahdi-base.c
index 7a46ecf..60a070e 100644
--- a/drivers/dahdi/dahdi-base.c
+++ b/drivers/dahdi/dahdi-base.c
@@ -4981,70 +4981,62 @@ static int dahdi_ioctl_iomux(struct file *file, unsigned long data)
 {
 	struct dahdi_chan *const chan = chan_from_file(file);
 	unsigned long flags;
-	int ret;
+	unsigned int iomask;
 	DEFINE_WAIT(wait);
 
-	if (!chan)
-		return -EINVAL;
+	if (get_user(iomask, (int __user *)data))
+		return -EFAULT;
 
-	get_user(chan->iomask, (int __user *)data);
-	if (!chan->iomask)
+	if (unlikely(!iomask || !chan))
 		return -EINVAL;
 
 	while (1) {
+		unsigned int wait_result;
 
-		ret = 0;
+		wait_result = 0;
 		prepare_to_wait(&chan->eventbufq, &wait, TASK_INTERRUPTIBLE);
 
 		spin_lock_irqsave(&chan->lock, flags);
-		/* if looking for read */
-		if (chan->iomask & DAHDI_IOMUX_READ) {
-			/* if read available */
+		chan->iomask = iomask;
+		if (iomask & DAHDI_IOMUX_READ) {
 			if ((chan->outreadbuf > -1)  && !chan->rxdisable)
-				ret |= DAHDI_IOMUX_READ;
+				wait_result |= DAHDI_IOMUX_READ;
 		}
-
-		/* if looking for write avail */
-		if (chan->iomask & DAHDI_IOMUX_WRITE) {
+		if (iomask & DAHDI_IOMUX_WRITE) {
 			if (chan->inwritebuf > -1)
-				ret |= DAHDI_IOMUX_WRITE;
+				wait_result |= DAHDI_IOMUX_WRITE;
 		}
-		/* if looking for write empty */
-		if (chan->iomask & DAHDI_IOMUX_WRITEEMPTY) {
+		if (iomask & DAHDI_IOMUX_WRITEEMPTY) {
 			/* if everything empty -- be sure the transmitter is
 			 * enabled */
 			chan->txdisable = 0;
 			if (chan->outwritebuf < 0)
-				ret |= DAHDI_IOMUX_WRITEEMPTY;
+				wait_result |= DAHDI_IOMUX_WRITEEMPTY;
 		}
-		/* if looking for signalling event */
-		if (chan->iomask & DAHDI_IOMUX_SIGEVENT) {
-			/* if event */
+		if (iomask & DAHDI_IOMUX_SIGEVENT) {
 			if (chan->eventinidx != chan->eventoutidx)
-				ret |= DAHDI_IOMUX_SIGEVENT;
+				wait_result |= DAHDI_IOMUX_SIGEVENT;
 		}
 		spin_unlock_irqrestore(&chan->lock, flags);
 
-		/* if something to return, or not to wait */
-		if (ret || (chan->iomask & DAHDI_IOMUX_NOWAIT)) {
-			/* set return value */
-			put_user(ret, (int __user *)data);
-			ret = 0;
-			break; /* get out of loop */
+		if (wait_result || (iomask & DAHDI_IOMUX_NOWAIT)) {
+			put_user(wait_result, (int __user *)data);
+			break;
 		}
 
-		if (!signal_pending(current)) {
-			schedule();
-			continue;
+		if (signal_pending(current)) {
+			finish_wait(&chan->eventbufq, &wait);
+			return -ERESTARTSYS;
 		}
 
-		ret = -ERESTARTSYS;
-		break;
+		schedule();
 	}
 
 	finish_wait(&chan->eventbufq, &wait);
+	spin_lock_irqsave(&chan->lock, flags);
 	chan->iomask = 0;
-	return ret;
+	spin_unlock_irqrestore(&chan->lock, flags);
+	return 0;
 }
 
 #ifdef CONFIG_DAHDI_MIRROR
diff --git a/include/dahdi/kernel.h b/include/dahdi/kernel.h
index d7b5ba1..f904da9 100644
--- a/include/dahdi/kernel.h
+++ b/include/dahdi/kernel.h
@@ -509,7 +509,7 @@ struct dahdi_chan {
 	int		cadencepos;				/*!< Where in the cadence we are */
 
 	/* I/O Mask */	
-	int		iomask;  /*! I/O Mux signal mask */
+	unsigned int iomask;  /*! I/O Mux signal mask */
 	wait_queue_head_t sel;	/*! thingy for select stuff */
 	
 	/* HDLC state machines */