This is a note to let you know that I've just added the patch titled
staging: comedi: prevent auto-unconfig of manually configured devices
to my staging git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git
in the staging-linus branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.
If you have any questions about this process, please let me know.
>From 7d3135af399e92cf4c9bbc5f86b6c140aab3b88c Mon Sep 17 00:00:00 2001
From: Ian Abbott <[email protected]>
Date: Tue, 4 Dec 2012 15:59:55 +0000
Subject: staging: comedi: prevent auto-unconfig of manually configured devices
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 <[email protected]>
Cc: stable <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/staging/comedi/comedi_fops.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/staging/comedi/comedi_fops.c
b/drivers/staging/comedi/comedi_fops.c
index b7bba17..9b038e4 100644
--- a/drivers/staging/comedi/comedi_fops.c
+++ b/drivers/staging/comedi/comedi_fops.c
@@ -1549,6 +1549,9 @@ static long comedi_unlocked_ioctl(struct file *file,
unsigned int cmd,
if (cmd == COMEDI_DEVCONFIG) {
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;
}
--
1.8.1.rc1.5.g7e0651a
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