On Wed, 13 Jan 2021, Maxime Ripard wrote:
> Hi!
>
> I've been trying to get a patch to rename any variable called "state" in
> a given set of callbacks.
>
> This is the patch that I've come up with:
>
> @ plane_atomic_func @
> identifier helpers;
> identifier func;
> @@
>
> (
> static const struct drm_plane_helper_funcs helpers = {
> ...,
> .atomic_check = func,
> ...,
> };
> |
> static const struct drm_plane_helper_funcs helpers = {
> ...,
> .atomic_disable = func,
> ...,
> };
> |
> static const struct drm_plane_helper_funcs helpers = {
> ...,
> .atomic_update = func,
> ...,
> };
> )
You don't need the ...s in the above. For structure declarations
Coccinelle is happy as long as what you specify is a subset of what is
present. The static and const aren't essential either. If you remove
them, the pattern will match whethe thy are present or not.
>
> @@
> identifier plane_atomic_func.func;
> symbol state;
> expression e;
> type T;
> @@
>
> func(...)
> {
> ...
> - T state = e;
> + T plane_state = e;
> <+...
> - state
> + plane_state
> ...+>
> }
>
> However, it seems like at least on a file (in Linux,
> drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_plane.c), it takes quite big
> performance hit with one CPU running at 100% until the timeout is hit.
>
> Replacing <+... by ... makes it work instantly, but doesn't really do
> what I'm expecting, so I guess it's a matter of the patch being
> subobtimal?
>
> Is there a more optimal way of doing it?
In your rule, I donkt think that there is really any essential connection
between the declaration and the use? You just want to change state to
plane_state when it occurs in one of the functions that you detected. So
you could at least try the following and see if it gives any false
positives:
@@
identifier plane_atomic_func.func;
symbol state;
expression e;
type T;
@@
func(...)
{
<...
(
- T state = e;
+ T plane_state = e;
|
- state
+ plane_state
)
...>
}
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