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-rw-r--r--drivers/staging/comedi/comedi_fops.c19
1 files changed, 16 insertions, 3 deletions
diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c
index 7525625..aeb2c00 100644
--- a/drivers/staging/comedi/comedi_fops.c
+++ b/drivers/staging/comedi/comedi_fops.c
@@ -83,7 +83,7 @@ static int do_subdinfo_ioctl(struct comedi_device *dev,
static int do_chaninfo_ioctl(struct comedi_device *dev,
struct comedi_chaninfo __user *arg);
static int do_bufinfo_ioctl(struct comedi_device *dev,
- struct comedi_bufinfo __user *arg);
+ struct comedi_bufinfo __user *arg, void *file);
static int do_cmd_ioctl(struct comedi_device *dev,
struct comedi_cmd __user *arg, void *file);
static int do_lock_ioctl(struct comedi_device *dev, unsigned int arg,
@@ -169,7 +169,8 @@ static long comedi_unlocked_ioctl(struct file *file, unsigned int cmd,
break;
case COMEDI_BUFINFO:
rc = do_bufinfo_ioctl(dev,
- (struct comedi_bufinfo __user *)arg);
+ (struct comedi_bufinfo __user *)arg,
+ file);
break;
case COMEDI_LOCK:
rc = do_lock_ioctl(dev, arg, file);
@@ -563,7 +564,7 @@ static int do_chaninfo_ioctl(struct comedi_device *dev,
*/
static int do_bufinfo_ioctl(struct comedi_device *dev,
- struct comedi_bufinfo __user *arg)
+ struct comedi_bufinfo __user *arg, void *file)
{
struct comedi_bufinfo bi;
struct comedi_subdevice *s;
@@ -576,6 +577,10 @@ static int do_bufinfo_ioctl(struct comedi_device *dev,
return -EINVAL;
s = dev->subdevices + bi.subdevice;
+
+ if (s->lock && s->lock != file)
+ return -EACCES;
+
async = s->async;
if (!async) {
@@ -588,6 +593,13 @@ static int do_bufinfo_ioctl(struct comedi_device *dev,
bi.bytes_written = 0;
goto copyback;
}
+ if (!s->busy) {
+ bi.bytes_read = 0;
+ bi.bytes_written = 0;
+ goto copyback_position;
+ }
+ if (s->busy != file)
+ return -EACCES;
if (bi.bytes_read && (s->subdev_flags & SDF_CMD_READ)) {
bi.bytes_read = comedi_buf_read_alloc(async, bi.bytes_read);
@@ -606,6 +618,7 @@ static int do_bufinfo_ioctl(struct comedi_device *dev,
comedi_buf_write_free(async, bi.bytes_written);
}
+copyback_position:
bi.buf_write_count = async->buf_write_count;
bi.buf_write_ptr = async->buf_write_ptr;
bi.buf_read_count = async->buf_read_count;
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