diff options
| author | Ian Abbott <abbotti@mev.co.uk> | 2016-02-19 16:13:51 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-02-20 15:25:58 -0800 |
| commit | 66c365026b18132b8d743254f0910be37565c5fa (patch) | |
| tree | e3e6d1af05dc2af9473197d43361a7627fe7bed4 /drivers/staging/comedi | |
| parent | e5be74c7c23b159aa43c7e6708e46d71a7af677d (diff) | |
staging: comedi: COMEDI_BUFINFO: force bytes_read or bytes_written to 0
The `COMEDI_BUFINFO` ioctl is used to advance the current position in
the buffer by a specified amount (which can be 0) and get the new
position. On input, the `bytes_read` member of `struct comedi_bufinfo`
specifies the amount to advance the "read" position for an asynchronous
command in the "read" direction, and the `bytes_written` member
specifies the amount to advance the "write" position for a command in
the "write" direction. The handler `do_bufinfo_ioctl()` may adjust
these by the amount the position is actually advanced before copying
them back to the user. Currently, it ignores the specified `bytes_read`
value for a command in the "write" direction, and ignores the specified
`bytes_written` for a command in the "read" direction, so the values
copied back to the user are unchanged. Change it to force the ignored
value to 0 before copying the values back to the user.
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/staging/comedi')
| -rw-r--r-- | drivers/staging/comedi/comedi_fops.c | 30 |
1 files changed, 18 insertions, 12 deletions
diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c index 2cfb61e0f2b8..04d6040246ee 100644 --- a/drivers/staging/comedi/comedi_fops.c +++ b/drivers/staging/comedi/comedi_fops.c @@ -1141,19 +1141,25 @@ static int do_bufinfo_ioctl(struct comedi_device *dev, if (s->busy != file) return -EACCES; - if (bi.bytes_read && !(async->cmd.flags & CMDF_WRITE)) { - comedi_buf_read_alloc(s, bi.bytes_read); - bi.bytes_read = comedi_buf_read_free(s, bi.bytes_read); - - if (comedi_is_subdevice_idle(s) && - comedi_buf_read_n_available(s) == 0) { - do_become_nonbusy(dev, s); + if (!(async->cmd.flags & CMDF_WRITE)) { + /* command was set up in "read" direction */ + if (bi.bytes_read) { + comedi_buf_read_alloc(s, bi.bytes_read); + bi.bytes_read = comedi_buf_read_free(s, bi.bytes_read); + + if (comedi_is_subdevice_idle(s) && + comedi_buf_read_n_available(s) == 0) + do_become_nonbusy(dev, s); } - } - - if (bi.bytes_written && (async->cmd.flags & CMDF_WRITE)) { - comedi_buf_write_alloc(s, bi.bytes_written); - bi.bytes_written = comedi_buf_write_free(s, bi.bytes_written); + bi.bytes_written = 0; + } else { + /* command was set up in "write" direction */ + if (bi.bytes_written) { + comedi_buf_write_alloc(s, bi.bytes_written); + bi.bytes_written = + comedi_buf_write_free(s, bi.bytes_written); + } + bi.bytes_read = 0; } copyback_position: |