Otherwise we can get an undesirable high latency on poll().
Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
---
drivers/media/video/gspca/gspca.c | 25 ++++++++++++++++++++-----
drivers/media/video/gspca/gspca.h | 8 ++++++--
2 files changed, 26 insertions(+), 7 deletions(-)
diff --git a/drivers/media/video/gspca/gspca.c b/drivers/media/video/gspca/gspca.c
index b3af68c..8dca187 100644
--- a/drivers/media/video/gspca/gspca.c
+++ b/drivers/media/video/gspca/gspca.c
@@ -1323,8 +1323,15 @@ static int dev_close(struct file *file)
struct gspca_dev *gspca_dev = video_drvdata(file);
PDEBUG(D_STREAM, "[%s] close", current->comm);
- if (mutex_lock_interruptible(&gspca_dev->queue_lock))
+
+ /* Needed for gspca_stream_off, always lock before queue_lock! */
+ if (mutex_lock_interruptible(&gspca_dev->usb_lock))
+ return -ERESTARTSYS;
+
+ if (mutex_lock_interruptible(&gspca_dev->queue_lock)) {
+ mutex_unlock(&gspca_dev->usb_lock);
return -ERESTARTSYS;
+ }
/* if the file did the capture, free the streaming resources */
if (gspca_dev->capt_file == file) {
@@ -1336,6 +1343,7 @@ static int dev_close(struct file *file)
}
module_put(gspca_dev->module);
mutex_unlock(&gspca_dev->queue_lock);
+ mutex_unlock(&gspca_dev->usb_lock);
PDEBUG(D_STREAM, "close done");
@@ -1981,6 +1989,10 @@ static int read_alloc(struct gspca_dev *gspca_dev,
int i, ret;
PDEBUG(D_STREAM, "read alloc");
+
+ if (mutex_lock_interruptible(&gspca_dev->usb_lock))
+ return -ERESTARTSYS;
+
if (gspca_dev->nframes == 0) {
struct v4l2_requestbuffers rb;
@@ -1991,7 +2003,7 @@ static int read_alloc(struct gspca_dev *gspca_dev,
ret = vidioc_reqbufs(file, gspca_dev, &rb);
if (ret != 0) {
PDEBUG(D_STREAM, "read reqbuf err %d", ret);
- return ret;
+ goto out;
}
memset(&v4l2_buf, 0, sizeof v4l2_buf);
v4l2_buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
@@ -2001,7 +2013,7 @@ static int read_alloc(struct gspca_dev *gspca_dev,
ret = vidioc_qbuf(file, gspca_dev, &v4l2_buf);
if (ret != 0) {
PDEBUG(D_STREAM, "read qbuf err: %d", ret);
- return ret;
+ goto out;
}
}
gspca_dev->memory = GSPCA_MEMORY_READ;
@@ -2011,6 +2023,8 @@ static int read_alloc(struct gspca_dev *gspca_dev,
ret = vidioc_streamon(file, gspca_dev, V4L2_BUF_TYPE_VIDEO_CAPTURE);
if (ret != 0)
PDEBUG(D_STREAM, "read streamon err %d", ret);
+out:
+ mutex_unlock(&gspca_dev->usb_lock);
return ret;
}
@@ -2266,13 +2280,14 @@ int gspca_dev_probe2(struct usb_interface *intf,
if (ret)
goto out;
- /* These ioctls use just queue_lock and not usb_lock.
- This improves latency if the usb lock is taken for a
+ /* These ioctls and the non ioctl fops use just queue_lock and not
+ usb_lock. This improves latency if the usb lock is taken for a
long time, e.g. when changing a control value, and a
new frame is ready to be dequeued. */
v4l2_dont_use_lock(&gspca_dev->vdev, VIDIOC_DQBUF);
v4l2_dont_use_lock(&gspca_dev->vdev, VIDIOC_QBUF);
v4l2_dont_use_lock(&gspca_dev->vdev, VIDIOC_QUERYBUF);
+ set_bit(V4L2_FL_DONT_USE_LOCK, &gspca_dev->vdev.flags);
/* init video stuff */
ret = video_register_device(&gspca_dev->vdev,
diff --git a/drivers/media/video/gspca/gspca.h b/drivers/media/video/gspca/gspca.h
index c1ebf7c..224d4d6 100644
--- a/drivers/media/video/gspca/gspca.h
+++ b/drivers/media/video/gspca/gspca.h
@@ -162,7 +162,7 @@ struct gspca_dev {
struct module *module; /* subdriver handling the device */
struct v4l2_device v4l2_dev;
struct usb_device *dev;
- struct file *capt_file; /* file doing video capture */
+ struct file *capt_file; /* file doing video capture (*) */
#if defined(CONFIG_INPUT) || defined(CONFIG_INPUT_MODULE)
struct input_dev *input_dev;
char phys[64]; /* physical device path */
@@ -192,7 +192,7 @@ struct gspca_dev {
u8 fr_o; /* next frame to dequeue */
__u8 last_packet_type;
__s8 empty_packet; /* if (-1) don't check empty packets */
- __u8 streaming;
+ __u8 streaming; /* protected by usb_lock */
__u8 curr_mode; /* current camera mode */
__u32 pixfmt; /* current mode parameters */
@@ -214,6 +214,10 @@ struct gspca_dev {
__u8 iface; /* USB interface number */
__u8 alt; /* USB alternate setting */
u8 audio; /* presence of audio device */
+
+ /* (*) These variables are proteced by both usb_lock and queue_lock,
+ that is any code setting them is holding *both*, which means that
+ any code getting them needs to hold at least one of them */
};
int gspca_dev_probe(struct usb_interface *intf,
--
1.7.10
--
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