diff options
author | Ian Abbott <abbotti@mev.co.uk> | 2013-12-11 18:51:02 +0400 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-12-18 01:09:43 +0400 |
commit | 8f988d8784e3fa4bb50dabeec516cd3fbdb4ea73 (patch) | |
tree | f211190884237decdecc0e1715b37343bc877369 /drivers/staging/comedi | |
parent | a3b22220a48bd14c9ba4ca8d051b0c92d5bc3866 (diff) | |
download | linux-8f988d8784e3fa4bb50dabeec516cd3fbdb4ea73.tar.xz |
staging/comedi: keep reference to class device after destroyed
When a dynamically allocated `struct comedi_device` gets automatically
unconfigured by a call to `comedi_auto_unconfig()` from a lower-level
driver's bus removal function (e.g. when a USB device is disconnected),
the class device in `dev->class_dev` (where `dev` points to the `struct
comedi_device`) is destroyed by a call to `device_destroy()` that
matches a previous call to `device_create()`.
However, if the `struct comedi_device` is still associated with an open
file object, the now invalid `dev->class_dev` pointer may still be
passed to `dev_printk()` (via `dev_dbg()` etc.), producing bogus output
or worse.
To fix this, call `get_device()` on the class device if
`device_create()` was successful. Add a matching call to `put_device()`
in `comedi_dev_kref_release()` when the `struct comedi_device` is freed.
The calls to `dev_dbg()` etc. after the call to `device_destroy()` will
still produce valid output, although the device will have been
unregistered in sysfs.
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 | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c index cdaef09c8993..6e5f538023c1 100644 --- a/drivers/staging/comedi/comedi_fops.c +++ b/drivers/staging/comedi/comedi_fops.c @@ -91,6 +91,7 @@ static void comedi_dev_kref_release(struct kref *kref) container_of(kref, struct comedi_device, refcount); mutex_destroy(&dev->mutex); + put_device(dev->class_dev); kfree(dev); } @@ -2514,7 +2515,7 @@ struct comedi_device *comedi_alloc_board_minor(struct device *hardware_device) csdev = device_create(comedi_class, hardware_device, MKDEV(COMEDI_MAJOR, i), NULL, "comedi%i", i); if (!IS_ERR(csdev)) - dev->class_dev = csdev; + dev->class_dev = get_device(csdev); /* Note: dev->mutex needs to be unlocked by the caller. */ return dev; |