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[media] pwc: poll(): Check that the device has not beem claimed for streaming already

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Some apps which use read() start the streaming through a call to poll(),
this means that if another app has already claimed the device for streaming
(through for example a s_fmt, or a reqbufs), that the poll should fail instead
of getting passed through to vb2_poll.

We only check for this when the app is polling for reads, so that ctrl events
still work.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Hans de Goede 2011-10-09 10:28:27 -03:00 committed by Mauro Carvalho Chehab
parent 0bf0f713d6
commit 296da3cd14
1 changed files with 9 additions and 0 deletions
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9
drivers/media/video/pwc/pwc-if.c
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@ -625,10 +625,19 @@ static ssize_t pwc_video_read(struct file *file, char __user *buf,
static unsigned int pwc_video_poll(struct file *file, poll_table *wait)
{
struct pwc_device *pdev = video_drvdata(file);
unsigned long req_events = poll_requested_events(wait);
if (!pdev->udev)
return POLL_ERR;
if ((req_events & (POLLIN | POLLRDNORM)) &&
pdev->vb_queue.num_buffers == 0 &&
!pdev->iso_init) {
/* This poll will start a read stream, check capt_file */
if (pwc_test_n_set_capt_file(pdev, file))
return POLL_ERR;
}
return vb2_poll(&pdev->vb_queue, file, wait);
}