1 files changed, 114 insertions, 139 deletions

diff --git a/arch/mips/kernel/rtlx.c b/arch/mips/kernel/rtlx.c
index d92c48e0d7a6..bfc8ca168f83 100644
--- a/arch/mips/kernel/rtlx.c
+++ b/arch/mips/kernel/rtlx.c
@@ -53,7 +53,8 @@ static char module_name[] = "rtlx";
 static struct chan_waitqueues {
 	wait_queue_head_t rt_queue;
 	wait_queue_head_t lx_queue;
-	int in_open;
+	atomic_t in_open;
+	struct mutex mutex;
 } channel_wqs[RTLX_CHANNELS];
 
 static struct irqaction irq;
@@ -146,110 +147,91 @@ static void stopping(int vpe)
 
 int rtlx_open(int index, int can_sleep)
 {
-	int ret;
+	struct rtlx_info **p;
 	struct rtlx_channel *chan;
-	volatile struct rtlx_info **p;
+	enum rtlx_state state;
+	int ret = 0;
 
 	if (index >= RTLX_CHANNELS) {
 		printk(KERN_DEBUG "rtlx_open index out of range\n");
 		return -ENOSYS;
 	}
 
-	if (channel_wqs[index].in_open) {
-		printk(KERN_DEBUG "rtlx_open channel %d already opened\n", index);
-		return -EBUSY;
+	if (atomic_inc_return(&channel_wqs[index].in_open) > 1) {
+		printk(KERN_DEBUG "rtlx_open channel %d already opened\n",
+		       index);
+		ret = -EBUSY;
+		goto out_fail;
 	}
 
-	channel_wqs[index].in_open++;
-
 	if (rtlx == NULL) {
 		if( (p = vpe_get_shared(RTLX_TARG_VPE)) == NULL) {
 			if (can_sleep) {
-				DECLARE_WAITQUEUE(wait, current);
-
-				/* go to sleep */
-				add_wait_queue(&channel_wqs[index].lx_queue, &wait);
-
-				set_current_state(TASK_INTERRUPTIBLE);
-				while ((p = vpe_get_shared(RTLX_TARG_VPE)) == NULL) {
-					schedule();
-					set_current_state(TASK_INTERRUPTIBLE);
-				}
-
-				set_current_state(TASK_RUNNING);
-				remove_wait_queue(&channel_wqs[index].lx_queue, &wait);
-
-				/* back running */
+				__wait_event_interruptible(channel_wqs[index].lx_queue,
+				                           (p = vpe_get_shared(RTLX_TARG_VPE)),
+				                           ret);
+				if (ret)
+					goto out_fail;
 			} else {
-				printk( KERN_DEBUG "No SP program loaded, and device "
+				printk(KERN_DEBUG "No SP program loaded, and device "
 					"opened with O_NONBLOCK\n");
-				channel_wqs[index].in_open = 0;
-				return -ENOSYS;
+				ret = -ENOSYS;
+				goto out_fail;
 			}
 		}
 
+		smp_rmb();
 		if (*p == NULL) {
 			if (can_sleep) {
-				DECLARE_WAITQUEUE(wait, current);
-
-				/* go to sleep */
-				add_wait_queue(&channel_wqs[index].lx_queue, &wait);
-
-				set_current_state(TASK_INTERRUPTIBLE);
-				while (*p == NULL) {
-					schedule();
-
-					/* reset task state to interruptable otherwise
-					   we'll whizz round here like a very fast loopy
-					   thing. schedule() appears to return with state
-					   set to TASK_RUNNING.
-
-					   If the loaded SP program, for whatever reason,
-					   doesn't set up the shared structure *p will never
-					   become true. So whoever connected to either /dev/rt?
-					   or if it was kspd, will then take up rather a lot of
-					   processor cycles.
-					*/
-
-					set_current_state(TASK_INTERRUPTIBLE);
+				DEFINE_WAIT(wait);
+
+				for (;;) {
+					prepare_to_wait(&channel_wqs[index].lx_queue, &wait, TASK_INTERRUPTIBLE);
+					smp_rmb();
+					if (*p != NULL)
+						break;
+					if (!signal_pending(current)) {
+						schedule();
+						continue;
+					}
+					ret = -ERESTARTSYS;
+					goto out_fail;
 				}
-
-				set_current_state(TASK_RUNNING);
-				remove_wait_queue(&channel_wqs[index].lx_queue, &wait);
-
-				/* back running */
-			}
-			else {
+				finish_wait(&channel_wqs[index].lx_queue, &wait);
+			} else {
 				printk(" *vpe_get_shared is NULL. "
 				       "Has an SP program been loaded?\n");
-				channel_wqs[index].in_open = 0;
-				return -ENOSYS;
+				ret = -ENOSYS;
+				goto out_fail;
 			}
 		}
 
 		if ((unsigned int)*p < KSEG0) {
 			printk(KERN_WARNING "vpe_get_shared returned an invalid pointer "
 			       "maybe an error code %d\n", (int)*p);
- 			channel_wqs[index].in_open = 0;
-			return -ENOSYS;
+			ret = -ENOSYS;
+			goto out_fail;
 		}
 
- 		if ((ret = rtlx_init(*p)) < 0) {
- 			channel_wqs[index].in_open = 0;
-  			return ret;
- 		}
+		if ((ret = rtlx_init(*p)) < 0)
+			goto out_ret;
 	}
 
 	chan = &rtlx->channel[index];
 
- 	if (chan->lx_state == RTLX_STATE_OPENED) {
- 		channel_wqs[index].in_open = 0;
-  		return -EBUSY;
- 	}
+	state = xchg(&chan->lx_state, RTLX_STATE_OPENED);
+	if (state == RTLX_STATE_OPENED) {
+		ret = -EBUSY;
+		goto out_fail;
+	}
 
-  	chan->lx_state = RTLX_STATE_OPENED;
- 	channel_wqs[index].in_open = 0;
-	return 0;
+out_fail:
+	smp_mb();
+	atomic_dec(&channel_wqs[index].in_open);
+	smp_mb();
+
+out_ret:
+	return ret;
 }
 
 int rtlx_release(int index)
@@ -270,30 +252,17 @@ unsigned int rtlx_read_poll(int index, int can_sleep)
 	/* data available to read? */
 	if (chan->lx_read == chan->lx_write) {
 		if (can_sleep) {
-			DECLARE_WAITQUEUE(wait, current);
-
-			/* go to sleep */
-			add_wait_queue(&channel_wqs[index].lx_queue, &wait);
-
-			set_current_state(TASK_INTERRUPTIBLE);
-			while (chan->lx_read == chan->lx_write) {
-				schedule();
+			int ret = 0;
 
-				set_current_state(TASK_INTERRUPTIBLE);
+			__wait_event_interruptible(channel_wqs[index].lx_queue,
+			                           chan->lx_read != chan->lx_write || sp_stopping,
+			                           ret);
+			if (ret)
+				return ret;
 
-				if (sp_stopping) {
-					set_current_state(TASK_RUNNING);
-					remove_wait_queue(&channel_wqs[index].lx_queue, &wait);
-					return 0;
-				}
-			}
-
-			set_current_state(TASK_RUNNING);
-			remove_wait_queue(&channel_wqs[index].lx_queue, &wait);
-
-			/* back running */
-		}
-		else
+			if (sp_stopping)
+				return 0;
+		} else
 			return 0;
 	}
 
@@ -320,56 +289,53 @@ unsigned int rtlx_write_poll(int index)
 	return write_spacefree(chan->rt_read, chan->rt_write, chan->buffer_size);
 }
 
-static inline void copy_to(void *dst, void *src, size_t count, int user)
+ssize_t rtlx_read(int index, void __user *buff, size_t count)
 {
-	if (user)
-		copy_to_user(dst, src, count);
-	else
-		memcpy(dst, src, count);
-}
-
-static inline void copy_from(void *dst, void *src, size_t count, int user)
-{
-	if (user)
-		copy_from_user(dst, src, count);
-	else
-		memcpy(dst, src, count);
-}
-
-ssize_t rtlx_read(int index, void *buff, size_t count, int user)
-{
-	size_t fl = 0L;
+	size_t lx_write, fl = 0L;
 	struct rtlx_channel *lx;
+	unsigned long failed;
 
 	if (rtlx == NULL)
 		return -ENOSYS;
 
 	lx = &rtlx->channel[index];
 
+	mutex_lock(&channel_wqs[index].mutex);
+	smp_rmb();
+	lx_write = lx->lx_write;
+
 	/* find out how much in total */
 	count = min(count,
-		     (size_t)(lx->lx_write + lx->buffer_size - lx->lx_read)
+		     (size_t)(lx_write + lx->buffer_size - lx->lx_read)
 		     % lx->buffer_size);
 
 	/* then how much from the read pointer onwards */
-	fl = min( count, (size_t)lx->buffer_size - lx->lx_read);
+	fl = min(count, (size_t)lx->buffer_size - lx->lx_read);
 
-	copy_to(buff, &lx->lx_buffer[lx->lx_read], fl, user);
+	failed = copy_to_user(buff, lx->lx_buffer + lx->lx_read, fl);
+	if (failed)
+		goto out;
 
 	/* and if there is anything left at the beginning of the buffer */
-	if ( count - fl )
-		copy_to (buff + fl, lx->lx_buffer, count - fl, user);
+	if (count - fl)
+		failed = copy_to_user(buff + fl, lx->lx_buffer, count - fl);
+
+out:
+	count -= failed;
 
-	/* update the index */
-	lx->lx_read += count;
-	lx->lx_read %= lx->buffer_size;
+	smp_wmb();
+	lx->lx_read = (lx->lx_read + count) % lx->buffer_size;
+	smp_wmb();
+	mutex_unlock(&channel_wqs[index].mutex);
 
 	return count;
 }
 
-ssize_t rtlx_write(int index, void *buffer, size_t count, int user)
+ssize_t rtlx_write(int index, const void __user *buffer, size_t count)
 {
 	struct rtlx_channel *rt;
+	unsigned long failed;
+	size_t rt_read;
 	size_t fl;
 
 	if (rtlx == NULL)
@@ -377,24 +343,35 @@ ssize_t rtlx_write(int index, void *buffer, size_t count, int user)
 
 	rt = &rtlx->channel[index];
 
+	mutex_lock(&channel_wqs[index].mutex);
+	smp_rmb();
+	rt_read = rt->rt_read;
+
 	/* total number of bytes to copy */
 	count = min(count,
-		    (size_t)write_spacefree(rt->rt_read, rt->rt_write,
-					    rt->buffer_size));
+		    (size_t)write_spacefree(rt_read, rt->rt_write, rt->buffer_size));
 
 	/* first bit from write pointer to the end of the buffer, or count */
 	fl = min(count, (size_t) rt->buffer_size - rt->rt_write);
 
-	copy_from (&rt->rt_buffer[rt->rt_write], buffer, fl, user);
+	failed = copy_from_user(rt->rt_buffer + rt->rt_write, buffer, fl);
+	if (failed)
+		goto out;
 
 	/* if there's any left copy to the beginning of the buffer */
-	if( count - fl )
-		copy_from (rt->rt_buffer, buffer + fl, count - fl, user);
+	if (count - fl) {
+		failed = copy_from_user(rt->rt_buffer, buffer + fl, count - fl);
+	}
 
-	rt->rt_write += count;
-	rt->rt_write %= rt->buffer_size;
+out:
+	count -= failed;
 
-	return(count);
+	smp_wmb();
+	rt->rt_write = (rt->rt_write + count) % rt->buffer_size;
+	smp_wmb();
+	mutex_unlock(&channel_wqs[index].mutex);
+
+	return count;
 }
 
 
@@ -446,7 +423,7 @@ static ssize_t file_read(struct file *file, char __user * buffer, size_t count,
 		return 0;	// -EAGAIN makes cat whinge
 	}
 
-	return rtlx_read(minor, buffer, count, 1);
+	return rtlx_read(minor, buffer, count);
 }
 
 static ssize_t file_write(struct file *file, const char __user * buffer,
@@ -454,28 +431,25 @@ static ssize_t file_write(struct file *file, const char __user * buffer,
 {
 	int minor;
 	struct rtlx_channel *rt;
-	DECLARE_WAITQUEUE(wait, current);
 
 	minor = iminor(file->f_path.dentry->d_inode);
 	rt = &rtlx->channel[minor];
 
 	/* any space left... */
 	if (!rtlx_write_poll(minor)) {
+		int ret = 0;
 
 		if (file->f_flags & O_NONBLOCK)
 			return -EAGAIN;
 
-		add_wait_queue(&channel_wqs[minor].rt_queue, &wait);
-		set_current_state(TASK_INTERRUPTIBLE);
-
-		while (!rtlx_write_poll(minor))
-			schedule();
-
-		set_current_state(TASK_RUNNING);
-		remove_wait_queue(&channel_wqs[minor].rt_queue, &wait);
+		__wait_event_interruptible(channel_wqs[minor].rt_queue,
+		                           rtlx_write_poll(minor),
+		                           ret);
+		if (ret)
+			return ret;
 	}
 
-	return rtlx_write(minor, (void *)buffer, count, 1);
+	return rtlx_write(minor, buffer, count);
 }
 
 static const struct file_operations rtlx_fops = {
@@ -513,7 +487,8 @@ static int rtlx_module_init(void)
 	for (i = 0; i < RTLX_CHANNELS; i++) {
 		init_waitqueue_head(&channel_wqs[i].rt_queue);
 		init_waitqueue_head(&channel_wqs[i].lx_queue);
-		channel_wqs[i].in_open = 0;
+		atomic_set(&channel_wqs[i].in_open, 0);
+		mutex_init(&channel_wqs[i].mutex);
 
 		dev = device_create(mt_class, NULL, MKDEV(major, i),
 		                    "%s%d", module_name, i);