diff options
| author | Ian Abbott <abbotti@mev.co.uk> | 2012-12-04 15:59:55 +0000 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2013-05-30 14:35:15 +0100 |
| commit | 2e4b48300640fd023e2644142ff11da6e88e9aa2 (patch) | |
| tree | b7541e2d38e14bf117223515ab58d24733fcbb6b | |
| parent | 0a686e3291bf91d6fa52046505002b2c6cb556a2 (diff) | |
staging: comedi: prevent auto-unconfig of manually configured devices
commit 7d3135af399e92cf4c9bbc5f86b6c140aab3b88c upstream.
When a low-level comedi driver auto-configures a device, a `struct
comedi_dev_file_info` is allocated (as well as a `struct
comedi_device`) by `comedi_alloc_board_minor()`. A pointer to the
hardware `struct device` is stored as a cookie in the `struct
comedi_dev_file_info`. When the low-level comedi driver
auto-unconfigures the device, `comedi_auto_unconfig()` uses the cookie
to find the `struct comedi_dev_file_info` so it can detach the comedi
device from the driver, clean it up and free it.
A problem arises if the user manually unconfigures and reconfigures the
comedi device using the `COMEDI_DEVCONFIG` ioctl so that is no longer
associated with the original hardware device. The problem is that the
cookie is not cleared, so that a call to `comedi_auto_unconfig()` from
the low-level driver will still find it, detach it, clean it up and free
it.
Stop this problem occurring by always clearing the `hardware_device`
cookie in the `struct comedi_dev_file_info` whenever the
`COMEDI_DEVCONFIG` ioctl call is successful.
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
| -rw-r--r-- | drivers/staging/comedi/comedi_fops.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c index a023f522408d..fe4dbf3af2ed 100644 --- a/drivers/staging/comedi/comedi_fops.c +++ b/drivers/staging/comedi/comedi_fops.c @@ -143,6 +143,9 @@ static long comedi_unlocked_ioctl(struct file *file, unsigned int cmd, } rc = do_devconfig_ioctl(dev, (struct comedi_devconfig __user *)arg); + if (rc == 0) + /* Evade comedi_auto_unconfig(). */ + dev_file_info->hardware_device = NULL; goto done; } |