Re: [PATCH 1/1] scheduler: access to variable out of scope insched_slice()

[Ingo Molnar]

* Christian Engelmayer <christian.engelmayer@xxxxxxxxxxxxxx> wrote:

> From: Christian Engelmayer <christian.engelmayer@xxxxxxxxxxxxxx>
> 
> Access to local variable lw is aliased by usage of pointer load. Access to
> pointer load in calc_delta_mine() happens when lw is already out of scope.
> 
> Signed-off-by: Christian Engelmayer <christian.engelmayer@xxxxxxxxxxxxxx>
> --
> Reported by static code analysis. 
> 
> --- linux-2.6.30/kernel/sched_fair.c.orig	2009-06-16 10:01:50.000000000 +0200
> +++ linux-2.6.30/kernel/sched_fair.c	2009-06-16 10:02:39.000000000 +0200
> @@ -430,12 +430,13 @@ static u64 sched_slice(struct cfs_rq *cf
>  
>  	for_each_sched_entity(se) {
>  		struct load_weight *load;
> +		struct load_weight lw;
>  
>  		cfs_rq = cfs_rq_of(se);
>  		load = &cfs_rq->load;
>  
>  		if (unlikely(!se->on_rq)) {
> -			struct load_weight lw = cfs_rq->load;
> +			lw = cfs_rq->load;
>  
>  			update_load_add(&lw, se->load.weight);
>  			load = &lw;

Good one!

I suspect it doesnt matter in practice because GCC will just have 
them all on the same stack frame?

	Ingo
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/