[media] em28xx-v4l: get rid of field "users" in struct em28xx_v4l2"

This reverts commit 747dba7de2a51a3db58b665ed3bc8c07921546ec.

It breaks concurrent vbi and video capturing:
While v4l2->users is the number of users of the whole device (all device nodes),
v4l2_fh_is_singular() only checks the number of users of a specific device node.
As a result. if one device node is open and a second device node is opened
(closed), the device is reinitialized (streaming is stopped).

Reported-by: Hans Verkuil <hans.verkuil@cisco.com>
Tested-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Signed-off-by: Frank Schäfer <fschaefer.oss@googlemail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

2 files changed, 11 insertions, 13 deletions

diff --git a/drivers/media/usb/em28xx/em28xx-video.c b/drivers/media/usb/em28xx/em28xx-video.c
index 41339259f30c..29abc379551e 100644
--- a/drivers/media/usb/em28xx/em28xx-video.c
+++ b/drivers/media/usb/em28xx/em28xx-video.c
@@ -1883,8 +1883,9 @@ static int em28xx_v4l2_open(struct file *filp)
                 return -EINVAL;
         }
 
-        em28xx_videodbg("open dev=%s type=%s\n",
-                        video_device_node_name(vdev), v4l2_type_names[fh_type]);
+        em28xx_videodbg("open dev=%s type=%s users=%d\n",
+                        video_device_node_name(vdev), v4l2_type_names[fh_type],
+                        v4l2->users);
 
         if (mutex_lock_interruptible(&dev->lock))
                 return -ERESTARTSYS;
@@ -1897,9 +1898,7 @@ static int em28xx_v4l2_open(struct file *filp)
                 return ret;
         }
 
-        if (v4l2_fh_is_singular_file(filp)) {
-                em28xx_videodbg("first opened filehandle, initializing device\n");
-
+        if (v4l2->users == 0) {
                 em28xx_set_mode(dev, EM28XX_ANALOG_MODE);
 
                 if (vdev->vfl_type != VFL_TYPE_RADIO)
@@ -1910,8 +1909,6 @@ static int em28xx_v4l2_open(struct file *filp)
                  * of some i2c devices
                  */
                 em28xx_wake_i2c(dev);
-        } else {
-                em28xx_videodbg("further filehandles are already opened\n");
         }
 
         if (vdev->vfl_type == VFL_TYPE_RADIO) {
@@ -1921,6 +1918,7 @@ static int em28xx_v4l2_open(struct file *filp)
 
         kref_get(&dev->ref);
         kref_get(&v4l2->ref);
+        v4l2->users++;
 
         mutex_unlock(&dev->lock);
 
@@ -2027,11 +2025,12 @@ static int em28xx_v4l2_close(struct file *filp)
         struct em28xx_v4l2    *v4l2 = dev->v4l2;
         int              errCode;
 
-        mutex_lock(&dev->lock);
+        em28xx_videodbg("users=%d\n", v4l2->users);
 
-        if (v4l2_fh_is_singular_file(filp)) {
-                em28xx_videodbg("last opened filehandle, shutting down device\n");
+        vb2_fop_release(filp);
+        mutex_lock(&dev->lock);
 
+        if (v4l2->users == 1) {
                 /* No sense to try to write to the device */
                 if (dev->disconnected)
                         goto exit;
@@ -2050,12 +2049,10 @@ static int em28xx_v4l2_close(struct file *filp)
                         em28xx_errdev("cannot change alternate number to "
                                         "0 (error=%i)\n", errCode);
                 }
-        } else {
-                em28xx_videodbg("further opened filehandles left\n");
         }
 
 exit:
-        vb2_fop_release(filp);
+        v4l2->users--;
         kref_put(&v4l2->ref, em28xx_free_v4l2);
         mutex_unlock(&dev->lock);
         kref_put(&dev->ref, em28xx_free_device);
diff --git a/drivers/media/usb/em28xx/em28xx.h b/drivers/media/usb/em28xx/em28xx.h
index 84ef8efdb148..4360338e7b31 100644
--- a/drivers/media/usb/em28xx/em28xx.h
+++ b/drivers/media/usb/em28xx/em28xx.h
@@ -524,6 +524,7 @@ struct em28xx_v4l2 {
         int sensor_yres;
         int sensor_xtal;
 
+        int users;              /* user count for exclusive use */
         int streaming_users;    /* number of actively streaming users */
 
         u32 frequency;          /* selected tuner frequency */