V4L/DVB (12004): poll method lose race condition

[net-next-2.6.git] / drivers / media / video / bt8xx / bttv-driver.c

diff --git a/drivers/media/video/bt8xx/bttv-driver.c b/drivers/media/video/bt8xx/bttv-driver.c
index 7c1f82661ee8988bb7659bf548dae505bce7b870..5eb1464af6703f3825599e05bc4683a2e09dc250 100644 (file)
--- a/drivers/media/video/bt8xx/bttv-driver.c
+++ b/drivers/media/video/bt8xx/bttv-driver.c
@@ -3152,6 +3152,7 @@ static unsigned int bttv_poll(struct file *file, poll_table *wait)
        struct bttv_fh *fh = file->private_data;
        struct bttv_buffer *buf;
        enum v4l2_field field;
+       unsigned int rc = POLLERR;
 
        if (V4L2_BUF_TYPE_VBI_CAPTURE == fh->type) {
                if (!check_alloc_btres(fh->btv,fh,RESOURCE_VBI))
@@ -3160,9 +3161,10 @@ static unsigned int bttv_poll(struct file *file, poll_table *wait)
        }
 
        if (check_btres(fh,RESOURCE_VIDEO_STREAM)) {
+               mutex_lock(&fh->cap.vb_lock);
                /* streaming capture */
                if (list_empty(&fh->cap.stream))
-                       return POLLERR;
+                       goto err;
                buf = list_entry(fh->cap.stream.next,struct bttv_buffer,vb.stream);
        } else {
                /* read() capture */
@@ -3191,11 +3193,12 @@ static unsigned int bttv_poll(struct file *file, poll_table *wait)
        poll_wait(file, &buf->vb.done, wait);
        if (buf->vb.state == VIDEOBUF_DONE ||
            buf->vb.state == VIDEOBUF_ERROR)
-               return POLLIN|POLLRDNORM;
-       return 0;
+               rc =  POLLIN|POLLRDNORM;
+       else
+               rc = 0;
 err:
        mutex_unlock(&fh->cap.vb_lock);
-       return POLLERR;
+       return rc;
 }
 
 static int bttv_open(struct file *file)