V4L/DVB (6583): Fix em28xx read stream locking
On some situations, closing an streaming application and re-opening were
returning -EBUSY.
Uses the same locking schema also present on cx88.
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
diff --git a/drivers/media/video/em28xx/em28xx-video.c b/drivers/media/video/em28xx/em28xx-video.c
index 5b17ca9..f019177 100644
--- a/drivers/media/video/em28xx/em28xx-video.c
+++ b/drivers/media/video/em28xx/em28xx-video.c
@@ -225,6 +225,44 @@
}
}
+/* Usage lock check functions */
+static int res_get(struct em28xx_fh *fh)
+{
+ struct em28xx *dev = fh->dev;
+ int rc = 0;
+
+ /* This instance already has stream_on */
+ if (fh->stream_on)
+ return rc;
+
+ mutex_lock(&dev->lock);
+
+ if (dev->stream_on)
+ rc = -EINVAL;
+ else {
+ dev->stream_on = 1;
+ fh->stream_on = 1;
+ }
+
+ mutex_unlock(&dev->lock);
+ return rc;
+}
+
+static int res_check(struct em28xx_fh *fh)
+{
+ return (fh->stream_on);
+}
+
+static void res_free(struct em28xx_fh *fh)
+{
+ struct em28xx *dev = fh->dev;
+
+ mutex_lock(&dev->lock);
+ fh->stream_on = 0;
+ dev->stream_on = 0;
+ mutex_unlock(&dev->lock);
+}
+
/*
* em28xx_v4l2_open()
* inits the device and starts isoc transfer
@@ -328,15 +366,16 @@
em28xx_videodbg("users=%d\n", dev->users);
+
+ if (res_check(fh))
+ res_free(fh);
+
mutex_lock(&dev->lock);
- if (fh->reader == 1)
- fh->reader = 0;
if (dev->users == 1) {
- dev->reader = 0;
-
em28xx_uninit_isoc(dev);
em28xx_release_buffers(dev);
+ dev->io = IO_NONE;
/* the device is already disconnect,
free the remaining resources */
@@ -377,16 +416,15 @@
struct em28xx_fh *fh = filp->private_data;
struct em28xx *dev = fh->dev;
+
+ if (unlikely(res_get(fh) < 0))
+ return -EBUSY;
+
mutex_lock(&dev->lock);
if (dev->type == V4L2_BUF_TYPE_VIDEO_CAPTURE)
em28xx_videodbg("V4l2_Buf_type_videocapture is set\n");
- if (dev->reader > 0 && fh->reader == 0) {
- mutex_unlock(&dev->lock);
- return -EBUSY;
- }
-
if (dev->type == V4L2_BUF_TYPE_VBI_CAPTURE) {
em28xx_videodbg("V4L2_BUF_TYPE_VBI_CAPTURE is set\n");
em28xx_videodbg("not supported yet! ...\n");
@@ -425,9 +463,6 @@
" the device again to choose the read method\n");
mutex_unlock(&dev->lock);
return -EINVAL;
- } else {
- dev->reader = 1;
- fh->reader = 1;
}
if (dev->io == IO_NONE) {
@@ -499,6 +534,9 @@
struct em28xx_fh *fh = filp->private_data;
struct em28xx *dev = fh->dev;
+ if (unlikely(res_get(fh) < 0))
+ return POLLERR;
+
mutex_lock(&dev->lock);
if (dev->state & DEV_DISCONNECTED) {
@@ -572,15 +610,10 @@
void *pos;
u32 i;
- mutex_lock(&dev->lock);
-
- if (dev->reader > 0 && fh->reader == 0) {
- mutex_unlock(&dev->lock);
+ if (unlikely(res_get(fh) < 0))
return -EBUSY;
- } else {
- dev->reader = 1;
- fh->reader = 1;
- }
+
+ mutex_lock(&dev->lock);
if (dev->state & DEV_DISCONNECTED) {
em28xx_videodbg("mmap: device not present\n");
@@ -1219,6 +1252,9 @@
if (list_empty(&dev->inqueue))
return -EINVAL;
+ if (unlikely(res_get(fh) < 0))
+ return -EBUSY;
+
dev->stream = STREAM_ON; /* FIXME: Start video capture here? */
em28xx_videodbg("VIDIOC_STREAMON: starting stream\n");
@@ -1243,7 +1279,6 @@
}
}
- fh->reader = 0;
em28xx_empty_framequeues(dev);
mutex_unlock(&dev->lock);