[PATCH v2]saa7134-video.c: poll method lose race condition for capture video

[figo.zhang]

saa7134-video.c: poll method lose race condition for capture video.

In v2, when buf == NULL, it will goto err, return  "PULLERR"
immediately.

Signed-off-by: Figo.zhang <figo.zh...@kolorific.com>
---  
drivers/media/video/saa7134/saa7134-video.c |    9 ++++++---
 1 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/media/video/saa7134/saa7134-video.c 
b/drivers/media/video/saa7134/saa7134-video.c
index 493cad9..b1c2dbd 100644
--- a/drivers/media/video/saa7134/saa7134-video.c
+++ b/drivers/media/video/saa7134/saa7134-video.c
@@ -1423,11 +1423,13 @@ video_poll(struct file *file, struct poll_table_struct 
*wait)
 {
        struct saa7134_fh *fh = file->private_data;
        struct videobuf_buffer *buf = NULL;
+       unsigned int rc = 0;
 
        if (V4L2_BUF_TYPE_VBI_CAPTURE == fh->type)
                return videobuf_poll_stream(file, &fh->vbi, wait);
 
        if (res_check(fh,RESOURCE_VIDEO)) {
+               mutex_lock(&fh->cap.vb_lock);
                if (!list_empty(&fh->cap.stream))
                        buf = list_entry(fh->cap.stream.next, struct 
videobuf_buffer, stream);
        } else {
@@ -1446,13 +1448,14 @@ video_poll(struct file *file, struct poll_table_struct 
*wait)
        }
 
        if (!buf)
-               return POLLERR;
+               goto err;
 
        poll_wait(file, &buf->done, wait);
        if (buf->state == VIDEOBUF_DONE ||
            buf->state == VIDEOBUF_ERROR)
-               return POLLIN|POLLRDNORM;
-       return 0;
+               rc =  POLLIN|POLLRDNORM;
+       mutex_unlock(&fh->cap.vb_lock);
+       return rc;
 
 err:
        mutex_unlock(&fh->cap.vb_lock);


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