[Cocci] Finding missing return value checks for some function calls with SmPL

[julia.lawall@lip6.fr (Julia Lawall)]

On Fri, 2 Dec 2016, SF Markus Elfring wrote:

> > Now I wonder why the first assignment is not marked together with the function call
> > for further considerations by my source code analysis approach so far.
>
> I should have adjusted one of the used regular expressions a bit more like the following.
>
>
> @find_too_late_checking@
> expression ex1, ex2;
> identifier action1 =~ "^(?x)
> (?:
>    kzalloc
> |  kmalloc_array
> )$",
>            action2 =~ "^(?x)
> (?:
>    kzalloc
> |  kmalloc(?:_array)?
> )$",
>            work;
> type return_type;
> @@
>  return_type work(...)
>  {
>  ... when any
> *ex1 = action1(...);
>  ex2 = action2(...);
>  ... when any
>  }
>
>
> elfring at Sonne:~/Projekte/Coccinelle/janitor> spatch.opt show_too_late_checking2.cocci ../Probe/clk-mstp-excerpt1.c
> init_defs_builtins: /usr/local/lib64/coccinelle/standard.h
> HANDLING: ../Probe/clk-mstp-excerpt1.c
> diff =
> --- ../Probe/clk-mstp-excerpt1.c
> +++ /tmp/cocci-output-20109-52f048-clk-mstp-excerpt1.c
> @@ -5,7 +5,6 @@ static void __init cpg_mstp_clocks_init(
>  	struct clk **clks;
>  	unsigned int i;
>
> -	group = kzalloc(sizeof(*group), GFP_KERNEL);
>  	clks = kmalloc(MSTP_MAX_CLOCKS * sizeof(*clks), GFP_KERNEL);
>  	if (group == NULL || clks == NULL) {
>  		kfree(group);
>
>
> I imagine that there are further software improvements to consider around
> such use cases.

Not sure what you are asking about here.  Note that it is unlikely that
anyone would accept a patch on the above code.  Group is tested before it
is used.

julia