[media] tm6000: fix resource locking

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

2 files changed, 45 insertions, 15 deletions

diff --git a/drivers/staging/tm6000/tm6000-video.c b/drivers/staging/tm6000/tm6000-video.c
index 4a5fe6670fb..cb251af895b 100644
--- a/drivers/staging/tm6000/tm6000-video.c
+++ b/drivers/staging/tm6000/tm6000-video.c
@@ -788,25 +788,49 @@ static struct videobuf_queue_ops tm6000_video_qops = {
         IOCTL handling
    ------------------------------------------------------------------*/
 
-static int res_get(struct tm6000_core *dev, struct tm6000_fh *fh)
+static bool is_res_read(struct tm6000_core *dev, struct tm6000_fh *fh)
 {
-        /* is it free? */
-        if (dev->resources)
-                return 0;
-        /* it's free, grab it */
-        dev->resources =1;
-        dprintk(dev, V4L2_DEBUG_RES_LOCK, "res: get\n");
-        return 1;
+        /* Is the current fh handling it? if so, that's OK */
+        if (dev->resources == fh && dev->is_res_read)
+                return true;
+
+        return false;
+}
+
+static bool is_res_streaming(struct tm6000_core *dev, struct tm6000_fh *fh)
+{
+        /* Is the current fh handling it? if so, that's OK */
+        if (dev->resources == fh)
+                return true;
+
+        return false;
 }
 
-static int res_locked(struct tm6000_core *dev)
+static bool res_get(struct tm6000_core *dev, struct tm6000_fh *fh,
+                   bool is_res_read)
 {
-        return (dev->resources);
+        /* Is the current fh handling it? if so, that's OK */
+        if (dev->resources == fh && dev->is_res_read == is_res_read)
+                return true;
+
+        /* is it free? */
+        if (dev->resources)
+                return false;
+
+        /* grab it */
+        dev->resources = fh;
+        dev->is_res_read = is_res_read;
+        dprintk(dev, V4L2_DEBUG_RES_LOCK, "res: get\n");
+        return true;
 }
 
 static void res_free(struct tm6000_core *dev, struct tm6000_fh *fh)
 {
-        dev->resources = 0;
+        /* Is the current fh handling it? if so, that's OK */
+        if (dev->resources != fh)
+                return;
+
+        dev->resources = NULL;
         dprintk(dev, V4L2_DEBUG_RES_LOCK, "res: put\n");
 }
 
@@ -981,7 +1005,7 @@ static int vidioc_streamon(struct file *file, void *priv, enum v4l2_buf_type i)
         if (i != fh->type)
                 return -EINVAL;
 
-        if (!res_get(dev,fh))
+        if (!res_get(dev, fh, false))
                 return -EBUSY;
         return (videobuf_streamon(&fh->vb_vidq));
 }
@@ -1310,7 +1334,7 @@ tm6000_read(struct file *file, char __user *data, size_t count, loff_t *pos)
         struct tm6000_fh        *fh = file->private_data;
 
         if (fh->type==V4L2_BUF_TYPE_VIDEO_CAPTURE) {
-                if (res_locked(fh->dev))
+                if (!res_get(fh->dev, fh, true))
                         return -EBUSY;
 
                 return videobuf_read_stream(&fh->vb_vidq, data, count, pos, 0,
@@ -1328,7 +1352,10 @@ tm6000_poll(struct file *file, struct poll_table_struct *wait)
         if (V4L2_BUF_TYPE_VIDEO_CAPTURE != fh->type)
                 return POLLERR;
 
-        if (res_get(fh->dev,fh)) {
+        if (!!is_res_streaming(fh->dev, fh))
+                return POLLERR;
+
+        if (!is_res_read(fh->dev, fh)) {
                 /* streaming capture */
                 if (list_empty(&fh->vb_vidq.stream))
                         return POLLERR;
@@ -1356,6 +1383,7 @@ static int tm6000_release(struct file *file)
 
         dev->users--;
 
+        res_free(dev, fh);
         if (!dev->users) {
                 tm6000_uninit_isoc(dev);
                 videobuf_mmap_free(&fh->vb_vidq);
diff --git a/drivers/staging/tm6000/tm6000.h b/drivers/staging/tm6000/tm6000.h
index 5d9dcab5c87..a1c6ca2647e 100644
--- a/drivers/staging/tm6000/tm6000.h
+++ b/drivers/staging/tm6000/tm6000.h
@@ -189,7 +189,9 @@ struct tm6000_core {
         int                             users;
 
         /* various device info */
-        unsigned int                    resources;
+        struct tm6000_fh                *resources;     /* Points to fh that is streaming */
+        bool                            is_res_read;
+
         struct video_device             *vfd;
         struct tm6000_dmaqueue          vidq;
         struct v4l2_device              v4l2_dev;