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staging: comedi: replace __comedi_device_detach()

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`comedi_device_detach()` does nothing if the `struct comedi_device`'s
`attached` member is false, otherwise it calls
`__comedi_device_detach()` to do the real work.
`__comedi_device_detach()` is called from various other functions in
"drivers.c" (`comedi_device_postconfig()`, `comedi_device_attach()`, and
`comedi_auto_config()`) to bypass the check for the `attached` member
being false.

If we make `__comedi_device_detach()` safe to call when the `attached`
member is already false, we can remove the check in
`comedi_device_detach()`, subsume `__comedi_device_detach()` within
`comedi_device_detach()`, and replace all the calls to
`__comedi_device_detach()` with calls to `comedi_device_detach()`.

In fact, it is already safe to call `__comedi_device_detach()` when the
`attached` member is false.  We just need to remove the warning message
it outputs when the `driver` member is NULL.  Then the function becomes
idempotent without outputting spurious warnings.  (It is idempotent
because `dev->driver->detach()` will only be called once at most and the
call to `cleanup_device()` is idempotent itself.)

Combine `comedi_device_detach()` with `__comedi_device_detach()`,
removing the check for the `attached` member being false and removing
the warning about the `driver` member being NULL, and replace all calls
to `__comedi_device_detach()` with calls to the combined
`comedi_device_detach()`.

A beneficial side-effect of the above change is that a call to
`comedi_device_detach()` will always result in a call to
`cleanup_device()` and so always result in a call to
`comedi_clear_hw_dev()`.  We will make use of this beneficial
side-effect in a later patch.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ian Abbott 2013-04-04 14:58:58 +01:00 committed by Greg Kroah-Hartman
parent dcd7b8bd63
commit 016599f589
1 changed files with 4 additions and 14 deletions
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18
drivers/staging/comedi/drivers.c
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@ -119,24 +119,14 @@ static void cleanup_device(struct comedi_device *dev)
comedi_clear_hw_dev(dev);
}
static void __comedi_device_detach(struct comedi_device *dev)
void comedi_device_detach(struct comedi_device *dev)
{
dev->attached = false;
if (dev->driver)
dev->driver->detach(dev);
else
dev_warn(dev->class_dev,
"BUG: dev->driver=NULL in comedi_device_detach()\n");
cleanup_device(dev);
}
void comedi_device_detach(struct comedi_device *dev)
{
if (!dev->attached)
return;
__comedi_device_detach(dev);
}
static int poll_invalid(struct comedi_device *dev, struct comedi_subdevice *s)
{
return -EINVAL;
@ -283,7 +273,7 @@ static int comedi_device_postconfig(struct comedi_device *dev)
ret = __comedi_device_postconfig(dev);
if (ret < 0) {
__comedi_device_detach(dev);
comedi_device_detach(dev);
return ret;
}
if (!dev->board_name) {
@ -396,7 +386,7 @@ int comedi_device_attach(struct comedi_device *dev, struct comedi_devconfig *it)
dev->driver = driv;
ret = driv->attach(dev, it);
if (ret < 0) {
__comedi_device_detach(dev);
comedi_device_detach(dev);
module_put(dev->driver->module);
return ret;
}
@ -439,7 +429,7 @@ int comedi_auto_config(struct device *hardware_device,
comedi_dev->driver = driver;
ret = driver->auto_attach(comedi_dev, context);
if (ret < 0)
__comedi_device_detach(comedi_dev);
comedi_device_detach(comedi_dev);
else
ret = comedi_device_postconfig(comedi_dev);
mutex_unlock(&comedi_dev->mutex);