# Re: \[PATCH\] cocci: detect useless free(3) calls

- From: Junio C Hamano \<hidden\>
- Date: 2017-02-11 19:01:13 
- List: git
- Page: https://ratatoskr.run/git/2017/02/7707536

```text
René Scharfe [ref] writes:

> Add a semantic patch for removing checks that cause free(3) to only be
> called with a NULL pointer, as that must be a programming mistake.
>
> Signed-off-by: Rene Scharfe <redacted>
> ---
> No cases are found in master or next, but 1d263b93 (bisect--helper:
> `bisect_next_check` & bisect_voc shell function in C) introduced four
> of them to pu.

Thanks.  This should have been caught by code inspection, but
having automated way to do so is always good.

>
>  contrib/coccinelle/free.cocci | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/contrib/coccinelle/free.cocci b/contrib/coccinelle/free.cocci
> index e28213161a..c03ba737e5 100644
> --- a/contrib/coccinelle/free.cocci
> +++ b/contrib/coccinelle/free.cocci
> @@ -3,3 +3,9 @@ expression E;
>  @@
>  - if (E)
>    free(E);
> +
> +@@
> +expression E;
> +@@
> +- if (!E)
> +  free(E);
```