V4L/DVB (12004): poll method lose race condition
Figo.zhang [Tue, 16 Jun 2009 16:31:29 +0000 (13:31 -0300)]
bttv-driver.c,cx23885-video.c,cx88-video.c: poll method lose race condition for capture video.

Signed-off-by: Figo.zhang <figo1802@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/bt8xx/bttv-driver.c
drivers/media/video/cx23885/cx23885-video.c
drivers/media/video/cx88/cx88-video.c

index 7c1f826..5eb1464 100644 (file)
@@ -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)
index 68068c6..66bbd2e 100644 (file)
@@ -796,6 +796,7 @@ static unsigned int video_poll(struct file *file,
 {
        struct cx23885_fh *fh = file->private_data;
        struct cx23885_buffer *buf;
+       unsigned int rc = POLLERR;
 
        if (V4L2_BUF_TYPE_VBI_CAPTURE == fh->type) {
                if (!res_get(fh->dev, fh, RESOURCE_VBI))
@@ -803,23 +804,28 @@ static unsigned int video_poll(struct file *file,
                return videobuf_poll_stream(file, &fh->vbiq, wait);
        }
 
+       mutex_lock(&fh->vidq.vb_lock);
        if (res_check(fh, RESOURCE_VIDEO)) {
                /* streaming capture */
                if (list_empty(&fh->vidq.stream))
-                       return POLLERR;
+                       goto done;
                buf = list_entry(fh->vidq.stream.next,
                        struct cx23885_buffer, vb.stream);
        } else {
                /* read() capture */
                buf = (struct cx23885_buffer *)fh->vidq.read_buf;
                if (NULL == buf)
-                       return POLLERR;
+                       goto done;
        }
        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;
+done:
+       mutex_unlock(&fh->vidq.vb_lock);
+       return rc;
 }
 
 static int video_release(struct file *file)
index d6d6d13..0ccac70 100644 (file)
@@ -869,6 +869,7 @@ video_poll(struct file *file, struct poll_table_struct *wait)
 {
        struct cx8800_fh *fh = file->private_data;
        struct cx88_buffer *buf;
+       unsigned int rc = POLLERR;
 
        if (V4L2_BUF_TYPE_VBI_CAPTURE == fh->type) {
                if (!res_get(fh->dev,fh,RESOURCE_VBI))
@@ -876,22 +877,27 @@ video_poll(struct file *file, struct poll_table_struct *wait)
                return videobuf_poll_stream(file, &fh->vbiq, wait);
        }
 
+       mutex_lock(&fh->vidq.vb_lock);
        if (res_check(fh,RESOURCE_VIDEO)) {
                /* streaming capture */
                if (list_empty(&fh->vidq.stream))
-                       return POLLERR;
+                       goto done;
                buf = list_entry(fh->vidq.stream.next,struct cx88_buffer,vb.stream);
        } else {
                /* read() capture */
                buf = (struct cx88_buffer*)fh->vidq.read_buf;
                if (NULL == buf)
-                       return POLLERR;
+                       goto done;
        }
        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;
+done:
+       mutex_unlock(&fh->vidq.vb_lock);
+       return rc;
 }
 
 static int video_release(struct file *file)