Skip to contentSkip to conversation

cocci: remove unnecessary casts of void * while avoiding casts with __user or __force ?

DISCUSSION Joe Perches 2 participants 2 messages Aug 28, 2017 – Aug 29, 2017

lore
Share & tools
lore
#0 lore raw

A simple cocci script that removes unnecessary casts of a void * will also remove casts with __force or __user

e.g.:

-???????xemaclite_aligned_write(address_ptr, (u32 __force *) addr, ETH_ALEN); +???????xemaclite_aligned_write(address_ptr, addr, ETH_ALEN);

Is there a simple mechanism to avoid converting those?

$ cat void.cocci
@@
type T;
void *v;
expression e;
@@

- e = (T *)v;
+ e = v;

@@
identifier f;
type T;
void *v;
@@

	f(...,
-	(T *)v,
+	v,
	...)

$

#1 lore raw
Quoted 2 lines · Joe Perches

A simple cocci script that removes unnecessary casts of a void * will also remove casts with __force or __user

Unfortunately, attributes are currently not supported inside casts. This can be done in a hackish way (possible false negatives) as follows:

---

@initialize:ocaml@
@@

let close (p1,p2) =
let r = (List.hd p1).line_end in
let l = (List.hd p2).line in
let rc = (List.hd p1).col_end in
let lc = (List.hd p2).col in
r = l && lc = rc+1

@r@
position p1,p2;
expression f,e;
type T;
@@

f(..., // generalize this rule as needed
(T at p1 *@p2)
e,...)

@@
position r.p2 : script:ocaml(r.p1) { close(p1,p2) }; position r.p1;
expression e;
type T;
@@

- (T at p1 *@p2)
e

---

Basically, it assumes that if the type and the * are more than one space apart then there is something important there, and the cast is not removed.

julia