linux-kernel - [PATCH 6/7] [media] cx88: don't use atomic_t for core->mpeg

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Date:	Mon, 4 Apr 2011 22:30:35 -0500
From:	Jonathan Nieder <jrnieder@...il.com>
To:	linux-media@...r.kernel.org
Cc:	Huber Andreas <hobrom@...ax.at>,
	Mauro Carvalho Chehab <mchehab@...hat.com>,
	Hans Verkuil <hverkuil@...all.nl>,
	linux-kernel@...r.kernel.org, Ben Hutchings <ben@...adent.org.uk>,
	Steven Toth <stoth@...nellabs.com>
Subject: [PATCH 6/7] [media] cx88: don't use atomic_t for core->mpeg_users

mpeg_users is always read or written with core->lock held except
in mpeg_release (where it looks like a bug).  A plain int is simpler
and faster.

Signed-off-by: Jonathan Nieder <jrnieder@...il.com>
---
 drivers/media/video/cx88/cx88-blackbird.c |   11 ++++++-----
 drivers/media/video/cx88/cx88.h           |    2 +-
 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/media/video/cx88/cx88-blackbird.c b/drivers/media/video/cx88/cx88-blackbird.c
index fa8e347..11e49bb 100644
--- a/drivers/media/video/cx88/cx88-blackbird.c
+++ b/drivers/media/video/cx88/cx88-blackbird.c
@@ -1073,7 +1073,7 @@ static int mpeg_open(struct file *file)
 		return err;
 	}
 
-	if (!atomic_read(&dev->core->mpeg_users) && blackbird_initialize_codec(dev) < 0) {
+	if (!dev->core->mpeg_users && blackbird_initialize_codec(dev) < 0) {
 		drv->request_release(drv);
 		mutex_unlock(&dev->core->lock);
 		return -EINVAL;
@@ -1101,7 +1101,7 @@ static int mpeg_open(struct file *file)
 	cx88_set_scale(dev->core, dev->width, dev->height,
 			fh->mpegq.field);
 
-	atomic_inc(&dev->core->mpeg_users);
+	dev->core->mpeg_users++;
 	mutex_unlock(&dev->core->lock);
 	return 0;
 }
@@ -1112,7 +1112,9 @@ static int mpeg_release(struct file *file)
 	struct cx8802_dev *dev = fh->dev;
 	struct cx8802_driver *drv = NULL;
 
-	if (dev->mpeg_active && atomic_read(&dev->core->mpeg_users) == 1)
+	mutex_lock(&dev->core->lock);
+
+	if (dev->mpeg_active && dev->core->mpeg_users == 1)
 		blackbird_stop_codec(dev);
 
 	cx8802_cancel_buffers(fh->dev);
@@ -1121,7 +1123,6 @@ static int mpeg_release(struct file *file)
 
 	videobuf_mmap_free(&fh->mpegq);
 
-	mutex_lock(&dev->core->lock);
 	file->private_data = NULL;
 	kfree(fh);
 
@@ -1131,7 +1132,7 @@ static int mpeg_release(struct file *file)
 	if (drv)
 		drv->request_release(drv);
 
-	atomic_dec(&dev->core->mpeg_users);
+	dev->core->mpeg_users--;
 
 	mutex_unlock(&dev->core->lock);
 
diff --git a/drivers/media/video/cx88/cx88.h b/drivers/media/video/cx88/cx88.h
index 3d32f4a..9e8176e 100644
--- a/drivers/media/video/cx88/cx88.h
+++ b/drivers/media/video/cx88/cx88.h
@@ -390,7 +390,7 @@ struct cx88_core {
 	/* various v4l controls */
 	u32                        freq;
 	atomic_t		   users;
-	atomic_t                   mpeg_users;
+	int                        mpeg_users;
 
 	/* cx88-video needs to access cx8802 for hybrid tuner pll access. */
 	struct cx8802_dev          *dvbdev;
-- 
1.7.5.rc0

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