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    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@gmail.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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