Commit 57c563bf authored by Ian Abbott's avatar Ian Abbott Committed by Greg Kroah-Hartman
Browse files

staging: comedi: COMEDI_BUFINFO: return error if no active command 



The `COMEDI_BUFINFO` ioctl is used to advance the current position in
the buffer and/or get the current buffer position.  If no asynchronous
command is active (started via the file object that issued this ioctl),
this information is meaningless.  Change it to return an error
(`-EINVAL`) in this case.  Prior to this change, if a command was
started via a different file object, the ioctl returned `-EACCES`, but
now it will return `-EINVAL`, which is consistent with the current
behavior of the "read" and "write" file operation handlers.

Signed-off-by: default avatarIan Abbott <abbotti@mev.co.uk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent bb0c6bfa

drivers/staging/comedi/comedi_fops.c

+2 −20
Original line number Diff line number Diff line
@@ -1123,24 +1123,8 @@ static int do_bufinfo_ioctl(struct comedi_device *dev, 


	async = s->async;



	if (!async) {

		dev_dbg(dev->class_dev,

			"subdevice does not have async capability\n");

		bi.buf_write_ptr = 0;

		bi.buf_read_ptr = 0;

		bi.buf_write_count = 0;

		bi.buf_read_count = 0;

		bi.bytes_read = 0;

		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 (!async || s->busy != file)

		return -EINVAL;



	if (!(async->cmd.flags & CMDF_WRITE)) {

		/* command was set up in "read" direction */
@@ -1165,7 +1149,6 @@ static int do_bufinfo_ioctl(struct comedi_device *dev, 
		bi.bytes_read = 0;

	}



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;
@@ -1174,7 +1157,6 @@ static int do_bufinfo_ioctl(struct comedi_device *dev, 
	if (become_nonbusy)

		do_become_nonbusy(dev, s);



copyback:

	if (copy_to_user(arg, &bi, sizeof(bi)))

		return -EFAULT;