[PATCH 4/4] em28xx-v4l: get rid of field "users" in struct em28xx_v4l2

[Frank Schäfer]

Instead of counting the number of opened file handles, use function
v4l2_fh_is_singular_file() in em28xx_v4l2_open() and em28xx_v4l2_close() to
determine if the file handle is the first/last opened one.

Signed-off-by: Frank Schäfer <fschaefer....@googlemail.com>
---
 drivers/media/usb/em28xx/em28xx-video.c | 23 +++++++++++++----------
 drivers/media/usb/em28xx/em28xx.h       |  1 -
 2 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/drivers/media/usb/em28xx/em28xx-video.c 
b/drivers/media/usb/em28xx/em28xx-video.c
index 3a7ec3b..087ccf9 100644
--- a/drivers/media/usb/em28xx/em28xx-video.c
+++ b/drivers/media/usb/em28xx/em28xx-video.c
@@ -1883,9 +1883,8 @@ static int em28xx_v4l2_open(struct file *filp)
                return -EINVAL;
        }
 
-       em28xx_videodbg("open dev=%s type=%s users=%d\n",
-                       video_device_node_name(vdev), v4l2_type_names[fh_type],
-                       v4l2->users);
+       em28xx_videodbg("open dev=%s type=%s\n",
+                       video_device_node_name(vdev), v4l2_type_names[fh_type]);
 
        if (mutex_lock_interruptible(&dev->lock))
                return -ERESTARTSYS;
@@ -1898,7 +1897,9 @@ static int em28xx_v4l2_open(struct file *filp)
                return ret;
        }
 
-       if (v4l2->users == 0) {
+       if (v4l2_fh_is_singular_file(filp)) {
+               em28xx_videodbg("first opened filehandle, initializing 
device\n");
+
                em28xx_set_mode(dev, EM28XX_ANALOG_MODE);
 
                if (vdev->vfl_type != VFL_TYPE_RADIO)
@@ -1909,6 +1910,8 @@ 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) {
@@ -1918,7 +1921,6 @@ static int em28xx_v4l2_open(struct file *filp)
 
        kref_get(&dev->ref);
        kref_get(&v4l2->ref);
-       v4l2->users++;
 
        mutex_unlock(&dev->lock);
 
@@ -2025,12 +2027,11 @@ static int em28xx_v4l2_close(struct file *filp)
        struct em28xx_v4l2    *v4l2 = dev->v4l2;
        int              errCode;
 
-       em28xx_videodbg("users=%d\n", v4l2->users);
-
-       vb2_fop_release(filp);
        mutex_lock(&dev->lock);
 
-       if (v4l2->users == 1) {
+       if (v4l2_fh_is_singular_file(filp)) {
+               em28xx_videodbg("last opened filehandle, shutting down 
device\n");
+
                /* No sense to try to write to the device */
                if (dev->disconnected)
                        goto exit;
@@ -2049,10 +2050,12 @@ 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:
-       v4l2->users--;
+       vb2_fop_release(filp);
        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 4360338..84ef8ef 100644
--- a/drivers/media/usb/em28xx/em28xx.h
+++ b/drivers/media/usb/em28xx/em28xx.h
@@ -524,7 +524,6 @@ 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 */
-- 
1.8.4.5

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