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

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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: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ian Abbott 2016-02-19 16:13:54 +00:00 • committed by Greg Kroah-Hartman
commit 57c563bf78
1 changed files with 2 additions and 20 deletions
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22
drivers/staging/comedi/comedi_fops.c
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@ -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 @@ copyback_position:
if (become_nonbusy)
do_become_nonbusy(dev, s);
copyback:
if (copy_to_user(arg, &bi, sizeof(bi)))
return -EFAULT;