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authorIan Abbott <abbotti@mev.co.uk>2012-12-04 15:59:55 +0000
committerBen Hutchings <ben@decadent.org.uk>2013-05-30 14:35:15 +0100
commit2e4b48300640fd023e2644142ff11da6e88e9aa2 (patch)
parent0a686e3291bf91d6fa52046505002b2c6cb556a2 (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>
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;