[media] gspca: Use req_events in poll

So that we don't start a read stream when an app is only polling for control
events.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 26 insertions, 18 deletions

diff --git a/drivers/media/video/gspca/gspca.c b/drivers/media/video/gspca/gspca.c
index d9df30917374..8b97f777ddf4 100644
--- a/drivers/media/video/gspca/gspca.c
+++ b/drivers/media/video/gspca/gspca.c
@@ -2030,31 +2030,39 @@ out:
 static unsigned int dev_poll(struct file *file, poll_table *wait)
 {
         struct gspca_dev *gspca_dev = video_drvdata(file);
-        int ret;
+        unsigned long req_events = poll_requested_events(wait);
+        int ret = 0;
 
         PDEBUG(D_FRAM, "poll");
 
-        poll_wait(file, &gspca_dev->wq, wait);
+        if (req_events & POLLPRI)
+                ret |= v4l2_ctrl_poll(file, wait);
 
-        /* if reqbufs is not done, the user would use read() */
-        if (gspca_dev->memory == GSPCA_MEMORY_NO) {
-                ret = read_alloc(gspca_dev, file);
-                if (ret != 0)
-                        return POLLERR;
-        }
+        if (req_events & (POLLIN | POLLRDNORM)) {
+                /* if reqbufs is not done, the user would use read() */
+                if (gspca_dev->memory == GSPCA_MEMORY_NO) {
+                        if (read_alloc(gspca_dev, file) != 0) {
+                                ret |= POLLERR;
+                                goto out;
+                        }
+                }
 
-        if (mutex_lock_interruptible(&gspca_dev->queue_lock) != 0)
-                return POLLERR;
+                poll_wait(file, &gspca_dev->wq, wait);
 
-        /* check if an image has been received */
-        if (gspca_dev->fr_o != atomic_read(&gspca_dev->fr_i))
-                ret = POLLIN | POLLRDNORM;      /* yes */
-        else
-                ret = 0;
-        ret |= v4l2_ctrl_poll(file, wait);
-        mutex_unlock(&gspca_dev->queue_lock);
+                /* check if an image has been received */
+                if (mutex_lock_interruptible(&gspca_dev->queue_lock) != 0) {
+                        ret |= POLLERR;
+                        goto out;
+                }
+                if (gspca_dev->fr_o != atomic_read(&gspca_dev->fr_i))
+                        ret |= POLLIN | POLLRDNORM;
+                mutex_unlock(&gspca_dev->queue_lock);
+        }
+
+out:
         if (!gspca_dev->present)
-                return POLLHUP;
+                ret |= POLLHUP;
+
         return ret;
 }