2 files changed, 41 insertions, 13 deletions

diff --git a/drivers/media/video/soc_camera.c b/drivers/media/video/soc_camera.c
index c947525c3f2f..322f837bcfea 100644
--- a/drivers/media/video/soc_camera.c
+++ b/drivers/media/video/soc_camera.c
@@ -179,11 +179,9 @@ static int soc_camera_dqbuf(struct file *file, void *priv,
 
 static int soc_camera_open(struct inode *inode, struct file *file)
 {
-        struct video_device *vdev = video_devdata(file);
-        struct soc_camera_device *icd = container_of(vdev->dev,
-                                             struct soc_camera_device, dev);
-        struct soc_camera_host *ici =
-                to_soc_camera_host(icd->dev.parent);
+        struct video_device *vdev;
+        struct soc_camera_device *icd;
+        struct soc_camera_host *ici;
         struct soc_camera_file *icf;
         int ret;
 
@@ -191,7 +189,12 @@ static int soc_camera_open(struct inode *inode, struct file *file)
         if (!icf)
                 return -ENOMEM;
 
-        icf->icd = icd;
+        /* Protect against icd->remove() until we module_get() both drivers. */
+        mutex_lock(&video_lock);
+
+        vdev = video_devdata(file);
+        icd = container_of(vdev->dev, struct soc_camera_device, dev);
+        ici = to_soc_camera_host(icd->dev.parent);
 
         if (!try_module_get(icd->ops->owner)) {
                 dev_err(&icd->dev, "Couldn't lock sensor driver.\n");
@@ -205,6 +208,22 @@ static int soc_camera_open(struct inode *inode, struct file *file)
                 goto emgi;
         }
 
+        icd->use_count++;
+
+        icf->icd = icd;
+
+        /* Now we really have to activate the camera */
+        if (icd->use_count == 1) {
+                ret = ici->add(icd);
+                if (ret < 0) {
+                        dev_err(&icd->dev, "Couldn't activate the camera: %d\n", ret);
+                        icd->use_count--;
+                        goto eiciadd;
+                }
+        }
+
+        mutex_unlock(&video_lock);
+
         file->private_data = icf;
         dev_dbg(&icd->dev, "camera device open\n");
 
@@ -216,9 +235,13 @@ static int soc_camera_open(struct inode *inode, struct file *file)
 
         return 0;
 
+        /* All errors are entered with the video_lock held */
+eiciadd:
+        module_put(ici->owner);
 emgi:
         module_put(icd->ops->owner);
 emgd:
+        mutex_unlock(&video_lock);
         vfree(icf);
         return ret;
 }
@@ -230,8 +253,14 @@ static int soc_camera_close(struct inode *inode, struct file *file)
         struct soc_camera_host *ici = to_soc_camera_host(icd->dev.parent);
         struct video_device *vdev = icd->vdev;
 
+        mutex_lock(&video_lock);
+        icd->use_count--;
+        if (!icd->use_count)
+                ici->remove(icd);
         module_put(icd->ops->owner);
         module_put(ici->owner);
+        mutex_unlock(&video_lock);
+
         vfree(file->private_data);
 
         dev_dbg(vdev->dev, "camera device close\n");
@@ -673,14 +702,14 @@ static int soc_camera_probe(struct device *dev)
         if (!icd->probe)
                 return -ENODEV;
 
+        /* We only call ->add() here to activate and probe the camera.
+         * We shall ->remove() and deactivate it immediately afterwards. */
         ret = ici->add(icd);
         if (ret < 0)
                 return ret;
 
         ret = icd->probe(icd);
-        if (ret < 0)
-                ici->remove(icd);
-        else {
+        if (ret >= 0) {
                 const struct v4l2_queryctrl *qctrl;
 
                 qctrl = soc_camera_find_qctrl(icd->ops, V4L2_CID_GAIN);
@@ -689,6 +718,7 @@ static int soc_camera_probe(struct device *dev)
                 icd->exposure = qctrl ? qctrl->default_value :
                         (unsigned short)~0;
         }
+        ici->remove(icd);
 
         return ret;
 }
@@ -698,14 +728,10 @@ static int soc_camera_probe(struct device *dev)
 static int soc_camera_remove(struct device *dev)
 {
         struct soc_camera_device *icd = to_soc_camera_dev(dev);
-        struct soc_camera_host *ici =
-                to_soc_camera_host(icd->dev.parent);
 
         if (icd->remove)
                 icd->remove(icd);
 
-        ici->remove(icd);
-
         return 0;
 }
 
diff --git a/include/media/soc_camera.h b/include/media/soc_camera.h
index 69aba7188e44..c886b1e64872 100644
--- a/include/media/soc_camera.h
+++ b/include/media/soc_camera.h
@@ -41,6 +41,8 @@ struct soc_camera_device {
         int (*probe)(struct soc_camera_device *icd);
         void (*remove)(struct soc_camera_device *icd);
         struct module *owner;
+        /* soc_camera.c private count. Only accessed with video_lock held */
+        int use_count;
 };
 
 struct soc_camera_file {